Keto diet intermittent fasting


Keto and Intermittent Fasting: A Beginner’s Guide

When it comes to biohacking, there probably aren’t two more popular practices than the ketogenic high-fat diet and fasting.

Both regimens have health benefits including improved metabolism, weight loss, and even better cognitive function. Research studies have shown benefits for each, and personal stories on social media serve as some pretty profound anecdotes.

It might not be surprising that many often adopt a keto diet with intermittent fasting. Maybe you’re one of those people. This makes sense—keto and intermittent fasting actually have a lot in common. Keto works in many of the same ways that intermittent fasting works.

And, in fact, sticking to a low-carbohydrate or ketogenic diet might actually make it much, much easier to practice intermittent fasting. The synergy of keto with intermittent fasting can lead to some pretty remarkable benefits for you body. This article will explore why.

Overview of Ketosis

Ketosis is a metabolic state characterized by the presence of ketones in the blood. This occurs when the body is faced with a “challenge” of low blood sugar and reduced glycogen stores, which initiates a cascade of hormones that signal the body to begin breaking down fat stores and releasing fatty acids into the circulation.

Once in the circulation, these fatty acids are transported to the liver and used in the production of ketones—a process termed ketogenesis. In particular, the liver produces a ketone body known as acetoacetate (AcAc), a majority of which is turned into beta-hydroxybutyrate (BHB).

But what’s the purpose of ketosis?

Most of us know that our body can make energy by burning carbohydrates as well as fat. One of the major sources of energy for humans and animals is glucose—which we obtain primarily by consuming dietary carbohydrates: breads, fruits, vegetables, legumes, starches, and sugars. The breakdown of carbohydrates into glucose is one way that we maintain blood sugar. Lots of body tissues use glucose as a fuel—and some can’t use anything else (some eye cells and red blood cells, for instance).

In addition to glucose in the blood, we can store glucose in our muscles and liver as glycogen—long chains of glucose. We utilize glycogen during situations where blood glucose starts to run low—like during long-duration exercise.

Humans can also burn fat for energy, and several organs like the heart prefer fat as their main energy substrate.

Fat is also a great energy source because we have a lot of it! Even the skinniest among us have enough body fat to last a long time.

The purpose of ketosis is to provide fuel when the other sources of energy (mainly glucose) are running low. This was (and still is, perhaps) a survival mechanism that allowed organisms to survive under conditions where food supply was low. In order to keep energy levels high and maintain cognitive function, the liver produces ketones to serve as a metabolic fuel for the brain and body.

Ketones, unlike fatty acids, can cross the blood brain barrier that separates the brain from our circulation. In this way, the brain can have an energy source when glucose is low. During “starvation”, up to 60% of the brain’s energy might come from ketone body metabolism.

While ketosis isn’t necessarily needed for “survival” in our modern times, this “unique” metabolic state likely has some benefits. In this article, we will specifically talk about endogenous ketosis, since it best relates to intermittent fasting.

Benefits of Ketosis

Ketosis achieved through a ketogenic diet has been shown to have benefits for a wide variety of clinical conditions.

The keto diet originally started as a treatment for epilepsy, and is still used in this way today. The metabolism of ketones may have some potent brain benefits including a reduction of oxidative stress, lower levels of inflammation, and improved levels of various neurotransmitters involved in health and disease processes.1

The ketogenic diet has been shown to reduce the frequency of seizures in epileptic patients anywhere from 40 – 90%. These results are probably due to several mechanisms including increased GABA,2 reduced glutamate,3 higher activity of potassium ion channels,4 and reduced brain glucose metabolism.5

Other brain conditions that benefit from ketosis include Alzheimer’s disease and Parkinson’s disease.6,7,8,9,10 There is even some evidence that ketosis could improve mood, reduce migraines, and enhance mental focus.11,12,13,14

Along with brain health, ketosis is effective in treating metabolic conditions like type 2 diabetes, which is characterized by insulin resistance. The keto diet reduces blood glucose and lipids, increases weight loss, and improves insulin sensitivity15,16,17,18—all of which reduce the risk for diabetes and the metabolic syndrome or attenuate their negative effects.

The metabolic benefits of keto might extend to athletes as well, since ketosis is characterized by an increased capacity to burn fat.

Several studies have provided evidence that athletes on a keto diet can significantly improve their body composition—build lean muscle mass while reducing body fat.

Ketosis can be achieved endogenously (using exercise, fasting, or a ketogenic diet) or exogenously through the use of exogenous ketone supplements. Many benefits of ketosis are similar, regardless of the method achieved to induce it. However, some benefits are specific to endogenous ketosis—in particular those related to weight and fat loss.

This is also a benefit shared by intermittent fasting.

Fasting 101

You’ve likely heard of fasting in one way or another—it seems to be all over the media lately. Whether it’s being talked about as “biohacking” or an eating disorder, fasting is pretty controversial. In a world of overeating, not eating is polarizing. But while controversial, the data don’t lie. Research studies on fasting have shown that this lifestyle practice can have a multitude of health benefits—several of which are similar to those induced by ketosis.

This makes sense…since fasting leads to ketone production. Let’s take a look at how this happens.

What is Intermittent Fasting?

In simple terms, intermittent fasting refers to a reduced meal frequency. While there are many variations of IF, the most common forms include a once-weekly 24 hour fast, alternate day fasting (ADF) or a 5:2 fast—which involves fasting 2 consecutive days out of each week. The “intermittent” part of IF simply means that you aren’t necessarily fasting everyday.

That’s what differentiates IF from time-restricted feeding (TRF). TRF is the practice of reducing your eating window to anywhere from 4 – 10 hours during the day, and fasting the rest of the time. In contrast to IF, most people who practice TRF do so every day.

The Science of IF

Every time we eat, a metabolic response is triggered. If the meal contains carbohydrates, this metabolic response will include an increase in blood glucose (of varying degrees) and insulin. The pancreas releases insulin in order to facilitate the uptake of blood glucose into our skeletal muscles.

When insulin is released, it signals for the body to store excess energy as glycogen or adipose tissue. The primary storage sites are the liver and skeletal muscle. Along with upregulating processes for the storage of energy, insulin inhibits others—in particular those that release fat from our stored adipose tissue deposits.

Basically, insulin is a signal to “grow’ instead of “breakdown”—it’s anabolic rather than catabolic.

During fasting, since no food is coming in, blood glucose and insulin levels begin to drop. After a certain period of time, the body will start to burn fat and produce ketones. How long does it take?

After a single overnight fast, concentrations of ketones in the body are around 0.1 – 0.5mM, meaning you’ll be just below the “threshold” for ketosis. After 48 hours of fasting, ketones can reach 1 – 2mM. 5 days of fasting can increase ketone levels to around 7 – 8mM.19

Fat burning and ketone production are the primary outcomes of intermittent fasting, and two mechanisms that explain many of IF’s benefits.

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Benefits of Intermittent Fasting

There are several advantages to intermittent fasting—both physiological and psychological.

The first benefit may be for those looking to lose weight. While the research isn’t definitive on this, many people report that they find it much easier to stick to than traditional diets where you’re forced to consume much fewer calories than you need.

Some might find it easier to simply not eat than to chronically maintain calorie intake well below their means. This could be more of a psychological effect than something physical. In addition, IF may make it easier to meal plan (or not plan…if you catch our drift). If it’s one of your fasting days, you don’t have to worry about preparing a meal, making time to eat, or worrying about WHAT you’re going to eat. When done in the proper context, this could free up some time to be productive in work or hobbies.

Intermittent fasting is in its infancy as far as research goes, and most studies have been conducted in mice.

Lean and Mean

IF may benefit body composition. In humans, fasting for 24 hours may reduce weight and maintain that weight loss for up to 48 hours (most is likely just water weight). Multiple cycles of fasting (for example, weekly 24 hours fasts) could lead to long-term weight loss, however. This needs to be explored more in humans.

In mice, a diet that mimicked fasting and was repeated twice per month significantly reduced the amount of visceral fat in these rodents; with the added benefits of increased neurogenesis, improved cognitive performance, and bolstered immune system.20

Live Long and Prosper

It’s hard to study lifespan in humans, so in this area, we don’t have a lot of data on IF promoting a longer life. But, in rodent models, animals were fasted intermittently showed increased lifespan and healthspan compared to mice who ate more frequently.21 Lifespan might be enhanced through several mechanisms involving increased autophagy, reduced oxidative stress, and lower levels of insulin and insulin-like growth factor 1 (IGF-1).22,23,24,25,26,27

Metabolic Boost

Several aspects of metabolism and digestive health might improve through IF. Intermittent fasting has been shown to reduce levels of several risk factors for cardiovascular and heart disease including: blood lipids (cholesterol and triglycerides), blood glucose, insulin, blood pressure, and inflammation.28,29

These metabolic benefits might come from the effects that fasting has on regulating our circadian rhythms, sleep, and the gut microbiome.

Individuals who report practicing routine, periodic fasting (i.e. IF) have a lower risk of diabetes, reduced levels of blood glucose, and a lower body mass index.30 This shows that fasting might help prevent the onset of several metabolic diseases. However, fasting may also reverse aspects of diseases like type 2 diabetes.31,32 This might include reducing glucose and insulin or improving insulin sensitivity.

Brain Health

We’ve covered the body, what about the brain? This organ may too benefit from what IF has to offer. One benefit may relate directly to ketones—specifically beta-hydroxybutyrate (BHB). BHB is a strong stimulus for the release of a hormone known as brain-derived neurotrophic factor (BDNF) which promotes the growth of new neurons (called neurogenesis).33

Unfortunately, other “mental benefits” of fasting haven’t been studied. We don’t have studies on how fasting impacts cognitive function, mental clarity, or focus. However, one study that included 1,422 participants found evidence that physical and emotional well being improve during fasts lasting from 4 to 21 days in duration. This is some fairly strong data that fasting may not only be feasible, but beneficial for the brain in healthy individuals.34

Variations of Intermittent Fasting

Perhaps one of the most attractive aspects of fasting is that it is completely customizable. Whether you’re doing time restricted eating or a once-per week fast, YOU get to choose how to fit fasting into your life. And, since we don’t have data as to what the best fasting protocol is, the only thing that matters is how your fasting regimen uniquely benefits you and fits within your lifestyle.

While we mentioned that keto and intermittent fasting are often practiced together, they don’t have to be. For some people, that’s another attractive benefit of IF. Instead of focusing on exactly what to eat, with IF, you’re only worried about when you eat.

The 5:2 Fast

The 5:2 fast has its description in the name. Eat for 5 days each week, fast for 2. It sounds pretty simple, because it is. The 2 days must be consecutive, however; or at least that’s what is recommended by 5:2 advocates.

How do you go about eating on the 5 days when you aren’t fasting. Some people might just take up some sort of modified time-restricted feeding regimen and eat what they normally would. Others may just say “no rules.” When 5:2 fasting is described, the “feeding days” are usually said to be “ad libitum”—which essentially means you eat whatever you want. But keep it reasonable.

Alternate Day Fasting (ADF)

Alternate day fasting is another self-explanatory regimen.

In this fasting protocol, you eat every other day.

This means you’ll be eating 4 days out of every 7 during any week.

Similar to the 5:2 fast, the “feeding” days on ADF are supposed to be “ad libitum”, not putting restrictions on what or how much you eat.

Extended Water Fasting

While similar to 5:2 fasting and ADF, water fasting is a more prolonged IF regimen—typically involving a fast of anywhere from 48 to 72 hours or more where only water is consumed. Given the long time frame of water fasting, it is sometimes advised to consume some minerals and electrolytes like sodium, potassium, and magnesium.

Combining Keto and IF

We have mentioned more than once that fasting is super popular among people who are also following a ketogenic diet. There may be some solid theory behind this.

In fact, eating a ketogenic high-fat low-carb diet will make fasting easier and more manageable. This is because a keto diet will help you become more fat adapted, which will enhance your ability to perform an extended fast without feeling lethargic, depressed, or unbearably hungry.

Keto diets and intermittent fasting both have the same metabolic goals—train the body to efficiently burn fat for energy and get into a state of ketosis.

Both regimens do this by depleting glucose and lowering insulin levels in the body.

Another advantage of combining keto with intermittent fasting is that IF may help you get into ketosis even faster and perhaps achieve higher ketone levels.

Intermittent fasting promotes ketosis, and ketosis may help with intermittent fasting. A beautiful metabolic marriage.

Keto and IF Diet Plan

Maybe you’re thinking about trying the keto diet or experimenting with fasting. Perhaps you’re already doing both. Either way, we’ve provided a sample daily and weekly layout of what a plan might look like for someone on a keto diet who is also integrating some alternate-day fasting and 16:8 time-restricted feeding into their regimen.


6:00am: Water and/or black coffee (no, coffee won’t break the fast)

9:00am: More water or black coffee.

12:00pm: TRF ends. Have a keto-friendly meal: maybe a salad with grilled chicken topped with olive oil and feta cheese, avocado and some hard-boiled eggs or bacon bits.

3:00pm: Snack on some nuts or have some nut butter, and maybe coffee with some MCT oil or coconut oil.

6:00pm: 8 – 12oz of a fatty cut of meat (ribeye steak or fatty fish) plus some vegetables; maybe brussels sprouts cooked in butter.

8:00pm: Small snack of nuts, blueberries, and a piece of strong dark chocolate for “dessert”. This is your last meal of the day.

Monday: Same eating window as yesterday: 12 – 8 pm.

Tuesday: Fasting day. No calories consumed today.

Wednesday: Eating period of 12 – 8pm. You might be hungrier today since you fasted yesterday, especially if you did an early morning workout today.

Thursday: Fasting day

Friday: 12 – 8 eating window. Workout in the morning or, if you want to do a fueled workout, do so in between lunch and dinner.

Saturday: Fast day

Remember, this is only one example out of a nearly unlimited number of iterations! Change this up to fit your lifestyle, use it as a guide to design your own fasting regimen.

Bring on the Benefits

After all of the evidence presented, it’s hard to argue against the keto diet or intermittent fasting. They seem to benefit so many different physical conditions and diseases, along with having benefits for non-disease related functions.

It is said that the benefits of keto are basically due to the fact that it activates similar mechanisms to that of fasting—this is true. Fasting and ketosis both seem to call upon ancient biological pathways to promote stress resistance, survival, and longevity.

While we advocate both highly, don’t just jump right into fasting and ketosis without a bit of experience first. It takes some time to both metabolically and psychologically adapt to dietary regimens—especially prolonged fasting. Maybe try out TRF first along with a keto diet, and gradually progress your fasting periods.

If you’ve had a great experience with keto, IF, or both, tell us in the comments! We’d love to hear.

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The 90-Day Ketogenic Diet & Intermittent Fasting Experiment: How Does It Work?

Rand owensFollow Nov 28, 2017 · 12 min read 45 days into the experiment.

For the next 3 months, I decided to eat +160g of fat a day. Why would I do something this stupid, you ask? Because I am trying to get into the best shape of my life while increasing longevity.

Most of my life I have tried to find ways to optimize my body’s potential. Because of this, I have had the opportunity of trying numerous diets and training styles claiming to be the best.

If you have spent any time looking for a diet program on the internet, you know exactly what I am talking about. Every few years there’s some new miracle health secret being discussed or marketed all over social media sites like Facebook and Reddit. These fads even infiltrate top-level health forums and have fitness “gurus” swearing they are the answer to your prayers.

The ketogenic diet, however, is different. It has changed my life, and it deserves your attention. Not only has it helped me reduce my body fat and improved my cholesterol levels, but it also helped me feel more energetic in my day-to-day life and reduced my joint pain.

The ketogenic diet is a low-carb/high-fat diet that has been gaining popularity in recent years because of its very specific approach to controlling one’s weight.

The ketogenic diet certainly isn’t a “one-size-fits-all” solution, no diet is. However, since it has done wonders on my body, I am compelled to share more about it.

Because I had a lot of friends asking me about how I got in such great shape and why I looked/felt so healthy, I decided to perform an experiment and show others how this diet/lifestyle works. Providing a guide of sorts so other may test it out for themselves.

I also received a lot of pushback from friends who thought what I am doing is unhealthy.

I decided to do this study to show them that the program works and to dispel whatever misconception they have about the Keto diet and Intermittent Fasting.

At the end of the day, I am hoping that this study will inspire those who want to try the program to take action so they can experience a healthier and better life.

What is the Keto Diet:

Put simply; the ketogenic diet is a diet that is high in fat and very low in carbs which forces your body to start a process called nutritional ketosis. This means your body starts to burn stored fats for energy due to the lack of glucose in the bloodstream.

Glucose, also known as the body’s primary fuel source, is converted from carbohydrates. This is found in dozens of everyday food items — from white bread to fruits and vegetables.

Limiting these carb-rich foods to 25g a day is paramount to the ketogenic diet, but it doesn’t stop there.

To supply your body’s nutritional needs while maintaining ketosis, you will actually shift to eating high-fat foods with a moderate amount of protein. For example Fish, certain nuts, eggs, and most meat sources.

I use this Macro Calculator to figure out where my calories need to come from

Note: These macros are more of a guideline and not the rule.

As far as benefits go, the keto diet is usually applied with weight loss in mind. However, it is also shown to result in a number of benefits including increased energy levels, healthier inflammatory response, and improved blood sugar balance (among other things).

What is Intermittent Fasting:

For those who do not know what Intermittent Fasting (IF) is, it is basically a “cycle” between periods of fasting and healthy eating (NOT OVEREATING.)

A popular form of IF is the 16/8 method which entails fasting for 16 hours every day with an 8-hour eating window. Traditionally, during the fast you only consume water. However, some have been known to drink black coffee as there is some debate as to its effects on autophagy and fat loss.

I will be doing a full 24hrs worth of fasting before consuming my food. During every fast I will drink 3L of water so that I can keep my body hydrated and running efficiently.

With IF, insulin levels drop significantly — thus, accelerating the fat-burning mechanism of the body. It is also shown to reduce free radicals and boost the cellular repair processes in the body.

While there is undoubtedly more to IF than what I have mentioned, the above notes cover what you need to know for this study.

Combining the Keto Diet with Intermittent Fasting

By understanding their individual uses, you may think that the Keto diet and IF will be too taxing on the body when used together.

However, Based on my research, I believe that I have found the perfect way to piece them together into a single system and with the right implementation, one can incorporate the effects of being in ketosis with that of fasting.

For example, while gaining muscle mass is much harder with a ketogenic diet, IF solves this by improving the body’s insulin sensitivity, blood glucose regulation, and growth hormone production.

Fasting can also help your body achieve ketosis much faster.

Once you are in ketosis, it will be much easier to stick to your IF schedule since you will experience fewer hunger pains.

Remember that IF keeps your metabolism high, which helps you adapt quickly to your reduced carb intake.

Finally, being in ketosis while fasting allows your body to start using your body fat as a fuel source which leads to lower BF% and a leaner body overall.

If all these are proven to be true, then the Keto and IF combination would be a breakthrough.

With this 90-day Keto & IF experiment, I aim to affirm these claims by using my own body.

My Motivation

People commit to many diets and fitness routines for various reasons. Some do it to overcome physical concerns while others simply want to preserve good health.

My motivation for this routine is simple: I just want my passion and experiences to impact other people’s lives positively.

By acting as a “first-mover,” I hope to encourage readers to join the experiment and experience a healthier and better life.

I also want to help my medical friends and vegan followers to obtain a deeper understanding of how these practices affect the body.

Additionally, there’s a bonus for me as a biohacker looking to fully explore my body’s potential — as far as my DNA allows.

Without further ado, let’s get down to the nitty-gritty of the experiment.

Here’s the breakdown of the experiment:

To test my hypothesis that a high-fat diet, like the Keto diet, in conjunction with intermittent fasting can help fight high cholesterol, increase HDL, decrease body fat, decrease/eliminate joint pains, and accelerate muscle growth.

Objective Measurements:

Throughout this experiment, I will use the following key measurements to track my progress:

• Reductions in body fat percentage

• Increases in muscle mass

• Improvements in endurance and strength at the gym (See Google Sheets)

While I have calculated measurements of these pieces of information, I will be using DexaFit scans for confirmation purposes.

All of these will be recorded and tracked in Google Sheets and available once the experiment has concluded.

Start Date:

Finish Date:

Calorie Stats:

My BMR: 1697/cals

Calories Consumed (T/Th/Sat/Sun): 2196/cals

Calories Consumed (After 24hr Fast): 400cals


I will be honest, coming across definitely made transitioning into this lifestyle a lot easier. They have been a huge resource around understanding certain aspects of the Ketogenic diet, and they provide a number of fun recipes that make food fun.

Another great resource has been Dominic D’Agostino (@DominicDAgosti2) and the work he is doing with the ketogenic diet. After hearing him speak on The Joe Rogan Podcast (Ep:994), I was excited to find more information from him.

I recommend both of these resources for anyone wanting to understand more about the ketogenic diet or trying to answer questions that they might have about the diet.


To summarize this experiment, I will be following the ketogenic diet for 90-days without taking a break. I will also be fasting for 24hrs on Mondays, Wednesdays, and Fridays. By the end of each 24 hours, I will workout and cap it off with a keto meal that only has 25 grams of carbs and a load of fat. On Tuesdays, Thursdays, Saturdays, and Sundays, I will be eating 3–4 meals.

The majority of my calories will be consumed on my non-workout days. On non-fasting days I will be consuming a normal amount of calories, as I am not looking to make up for the calories, I did not consume during my fast.

During the fast the only thing I will be consuming is water. No black coffee. No zero calorie foods or beverages. WATER ONLY.

Workout and Cardio:

On Mondays, I will be working out Back and Bi’s. On Wednesdays, I will be working out chest, Shoulders, and Triceps. On Fridays, I will be doing Legs.

My exercises follow a TUT (time under tension) style. Doing 4 sets of 12–8 reps starting with lighter weight and gradually increasing.

Speed is the name of the game with contracting/squeezing the muscle and slowing down when releasing the weight (similar to performing a negative rep.)

With a 60sec rest period. All workouts will consist of 6–9 exercises total based on the body part or parts that are being trained that day.

It is important to note that no variables are changing in regards to my workout, from before or during the experiment. This is the same training style I have used for the last couple years. The only things that change are the amount of weight at which I use. As my strength goes up, I go up in weight to keep the same type of rep range and difficulty.

At the end of every workout, I do 13 minutes of HIIT cardio.

To keep my energy levels up during strength training, I use a couple of pre-workout supplements: For energy and pump I take Naked Energy (It’s Keto Approved), and for strength and endurance I mix in a scoop of Julian Bakery exogenous ketones. I have found that this really takes my workouts to the next level. I always suggest getting these two supplements to anyone that wants to get into keto.

Why I Do Cardio After My Workout

I keep my cardio towards the end of a workout, always. I do this because I’ve learned that lifting before cardio is much better for fat loss and workout energy efficiency. It takes a lot of effort to move heavy weights, so I do not want to waste it all by running beforehand!

To achieve a ripped/lean look your body needs to use your stored fat as fuel. In order to do this, you must burn off your glycogen stores first. When you lift weights, you typically use glycogen as fuel. By lifting weights before cardio, you can burn the majority of your glycogen stores. Knocking out your cardio after you crush the weights will burn more fat!

If You Aren’t Tracking It, You Aren’t Measuring It

For the sake of this experiment, I decided to get some baseline data on the measurements I am tracking.

First of all, I got my blood tested to acquire the necessary information, such as my thyroid stimulating hormone, cholesterol, triglycerides, HDL, and LDL.

The next thing I did was obtain my DexaFit scans, which gave me data about my body fat percentage, muscle mass profile, and other physiological data.

Here are the results:

• Total Body Fat Percentage: 17.6% (translates to 8–9% BF using calipers)

• Total Mass: 164.4 lbs.

• Fat Tissue: 28.9 lbs.

• Lean Tissue: 128.8 lbs.

• BMC: 6.7 lbs.

• Visceral Fat: 0.37 lbs.

Intermittent fasting is an effective fasting method with research-backed health benefits, including healthy weight loss, better cognitive function, and lower inflammation. It has become a popular tool for improving overall health and reaching nutrition and fitness goals. The most well-known, approachable, and sustainable method is intermittent fasting 16/8.

What Is Intermittent Fasting 16/8?

Intermittent fasting (IF), also known as time-restricted feeding, means eating within a specific daily window of time (feeding period) and fasting outside of that window (fasting period).

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There are several different types of intermittent fasting, but the 16/8 method is the most popular because it’s the easiest.

Doing an 16/8 intermittent fast means that you fast for 16 hours and eat only within an eight-hour window throughout the day, such as from noon to 8 p.m.

The easiest approach is to skip breakfast and have your first meal later in the day. For example, if you finish dinner by 8 p.m., you wouldn’t eat again until midday the next day.

Keep in mind 16/8 intermittent fasting is only one approach. The windows can vary based on what works for you. While some people might only eat within the same eight hours a day, others might only eat within a six-hour window (18/6) or four-hour window (20/4).

How the 16/8 Intermittent Fasting Diet Works

Like exercise, restricting calories is a helpful metabolic stressor. Eating within a certain time frame pushes your body in a different metabolic direction than if you were eating all the time.

Intermittent fasting can cause autophagy, which is a crucial defense mechanism against malignancy, infection, and neurodegenerative diseases. It’s basically your body’s way of cleaning out cells that aren’t performing at their best.

Research finds short-term fasting is an effective way of starting neuronal autophagy (cleaning up brain cells that aren’t doing well), therefore protecting your brain against neurodegenerative diseases.

Intermittent fasting also triggers a beneficial metabolic reaction that includes:

  • A decrease in inflammatory markers
  • Reduced blood glucose levels and insulin
  • An increase in the neurotrophin BDNF

These are powerful changes that can lead to several health improvements.

Health Benefits of 16/8 Intermittent Fasting

Adopting this eating style may seem difficult if you’ve never tried it before, but once you get used to it, it’s easy to follow. Plus, the research-backed benefits make it an excellent tool to improve your health.

Intermittent fasting 16/8 has been researched for its ability to improve multiple aspects of your health.

#1: Fat Loss

Intermittent fasting can help both healthy and overweight adults lose weight and body fat effectively. Human intervention trials have consistently found IF significantly reduces weight as your body is in a fat-burning mode more often.

In almost any type of fasting, losing weight is a natural byproduct because you’re consuming fewer calories.

#2: Improved Cognitive Function

Another perk of intermittent fasting is that it can improve brain function, boost focus, and get rid of brain fog.

Studies find that restricting calories moderately can:

  • Protect the brain by reducing oxidative damage to cellular proteins, lipids, and nucleic acids
  • Elevate levels of BDNF, an important neurotrophin that is needed for synaptic plasticity

#3: Lower Inflammation

IF is also great for your brain and might help you think clearer. Intermittent fasting, or restricting calories, also lowers markers of inflammation, which in turn aids cognitive function and protects your brain health.

#4: Lower Blood Pressure

Research finds intermittent fasting can help reduce blood pressure. According to a recent study, people that restricted eating habits to a smaller period of time lost weight from a lower calorie intake, which then helped them lower their blood pressure.

#5: Blood Sugar Control

Intermittent fasting is also an excellent tool for blood sugar regulation. Research has found that IF reduces blood sugar, insulin, and improves insulin sensitivity.

#6: Better Metabolic Health

Due to the different beneficial effects of intermittent fasting on health markers, it supports overall metabolic health.

Research finds intermittent fasting can improve metabolic profiles and reduce the risk of obesity and obesity-related conditions such as non-alcoholic fatty liver disease, and chronic diseases such as diabetes and cancer.

#7: Longevity

The positive effects IF can have on your metabolic health, inflammatory markers, and blood sugar levels may contribute to a longer lifespan and healthy aging.

Even though human trials are still needed to measure IF’s impact on longevity, multiple animal studies show calorie restriction results in an increased lifespan.

Another way intermittent fasting can improve your health is by facilitating ketosis.

How to Do Intermittent Fasting 16/8

To do intermittent fasting correctly and reap all the health benefits, here’s what to do:

  • Pick your fasting window: Choose what the hours of fasting will be. The easiest approach is to have an early dinner and skip your morning breakfast. For example, eating only from 1 p.m. to 9 p.m.
  • Have healthy meals during your eating window: A bad diet during your eating window can offset the metabolic benefits of intermittent fasting, so stick to nutritious whole foods. Here’s a list of the best keto-friendly foods to eat.
  • Eat fatty, satisfying meals: While you don’t need to be keto to try intermittent fasting, eating fatty foods will make it a lot easier and sustainable. Keto foods are healthy and satisfying, so you won’t be hungry during your fasting window. Practice smart snacking and you’ll do great.

Intermittent Fasting and Ketosis

One of the best things about fasting is that it can help you get into ketosis faster.

The two are related for a few reasons:

  1. For your body to get into ketosis, you must be fasting in some sense — either by not eating any food at all or by keeping carbs extremely low. When you’re in ketosis, it means your body is breaking down fat for energy.
  2. Intermittent fasting helps deplete your glucose stores at a faster rate, which speeds up the process of running on fat.
  3. Many people who start a ketogenic diet begin by fasting to enter ketosis more quickly.

So, is intermittent fasting 16/8 guaranteed to get you into ketosis? No, but it can help get you there if you do it along with a keto diet.

Intermittent Fasting 16/8 and the Keto Diet

There are three compelling reasons to combine intermittent fasting with a keto diet.

#1: Intermittent Fasting Is Not Enough to Keep You in Ketosis

The 16/8 fasting window may not be enough to get you into or keep you in ketosis. Even if you do end up in ketosis, if you continue to eat a diet with even a moderate amount of carbs it’ll probably kick you out of ketosis each time.

This can result in unpleasant side effects such as the keto flu and being overly hungry each time you start fasting again.

#2: The Keto Diet Makes Fasting Easier

Eating a ketogenic diet allows your body to become keto adapted (running on fat and not depending mainly on glucose).

This makes intermittent fasting much more comfortable because there’s no switching between glucose and ketones, thus eliminating the feeling of needing to eat every few hours.

#3: The Ketogenic Diet Keeps You Satisfied

Another great perk of the keto diet is its high level of satiety.

Not only does ketosis itself tend to stifle hunger, but the high level of healthy fat in the keto diet also makes it much easier to stay satisfied in a fasted state and eliminates those intense feelings of hunger and cravings throughout the day.

This is perfect for someone doing intermittent fasting.

How to Get Into Ketosis Using the 16/8 Method

While 16/8 intermittent fasting itself is not the only way to get into ketosis, it’s a good start.

To get into ketosis, the best way is to combine a healthy ketogenic diet with intermittent fasting. Taking exogenous ketones can also help with the transition period and reduce side effects.

Concerns About 16/8 Fasting

Intermittent fasting, especially the 16/8 approach, is completely safe and beneficial. Contrary to common belief, moderate calorie restriction is a healthy practice that improves your metabolic health.

However, if you’re using it to get into ketosis, it might not be enough to get you there. If your fasting goal is to enter ketosis, you also need to follow a keto diet.

The Bottom Line on Intermittent Fasting 16/8

Intermittent fasting is a safe and powerful tool for improving your health. To recap:

  • The 16/8 intermittent fasting approach means you fast for 16 hours and eat only in an eight-hour window.
  • Fasting triggers autophagy, which is needed for healthy metabolism.
  • IF has plenty of research-backed health benefits including better brain function, lower blood sugar levels, and lower inflammation.
  • Fasting can be a great way to get into ketosis, but it’s not the only way.
  • If you want to use fasting for ketosis, it’s ideal if you do it while following a keto diet.

“I can’t speak for anyone who would want to combine the two, but I personally would not,” he says. “It sounds like an overly regimented, restricted, and antisocial way to live.”

Intermittent fasting and keto might be tough to sustain when you’re out with friends at dinner or celebrating the holidays. You might be tempted to eat something that you “shouldn’t” eat or munch outside of your feeding window. And if you slip, you might be hard on yourself. For many, keto and intermittent fasting might not be sustainable.

There are even some pitfalls if you were to practice either eating style individually. For example, sometimes new keto dieters complain of getting “the keto flu” during their transition, which can include nausea, headaches, dizziness and stomach pain. A low-carb diet also runs the risk of not providing enough vitamins and nutrients like magnesium, potassium, calcium, and fiber.

“If you look at the healthiest, longest living populations in the world, these are people that tend to eat all food groups,” says Pasternak.

Even Mancinelli, who is a proponent of keto and fasting, thinks that “it’s not entirely necessary” to combine the two to get significant benefits. Nor is it necessarily needed to practice either eating pattern for life — particularly keto. You want to be “metabolically flexible” she says.

“You don’t want to also lose the ability to use glucose for energy because then when you do go back to eating something that’s glucose rich, your blood sugar is going to be fairly high,” says Mancinelli. “Now you’re going to have to develop the mechanisms to use that for energy again. You don’t just want to be in ketosis forever. I just am not clear that I see the benefit of that unless you’re using it as a treatment for some disease.”

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Who should avoid trying both?

Combining intermittent fasting and the ketogenic diet are particularly risky for certain populations, according to Mancinelli.

Children under the age of 18 who are still growing, for example, need to be able to eat when they feel like it. Those who are over the age of 65 may have trouble getting enough nutrients and calories to sustain certain body tissues and body mass, might want to avoid any restrictive eating regimens.

This can be true for anyone who has a nutritional deficiency or for someone who always has to take their medication with food. “It’s not that you can’t do intermittent fasting but you need to organize yourself,” says Mancinelli. “That can be a pain.”

Pregnant women who plan on breastfeeding after giving birth, might not want to hop straight into intermittent keto fasting to shed the baby weight. Producing milk requires a lot of energy and so restricting calories might not be the best move.

And if you’ve suffered or are suffering from any eating disorders, venturing into these two eating styles can be very emotionally triggering. It might be best to find other methods to reach your health goals.

What should I do if I’m interested in do keto and intermittent fasting together?

Always consult your doctor or registered dietician before changing up your eating habits. You want to have a solid game plan and know that you are practicing in a way that’s healthy for you.

If you’ve got the green light and don’t know where to start, Mancinelli suggests the easiest route is to give intermittent fasting a go first.

“What I recommend is trying something that is going to fit into your schedule,” she says. “Don’t focus on what’s the optimal number of hours that I should be fasting, but what works in your life. Do an inventory of when you eat and which meals are super important to you and say to yourself, ‘Which one could I cut out?'”

Then later on, you can try to tack on keto if you want and see how you feel. Again, consult your health professional and find a community that can inspire you to stay on track.

Whatever you decide to do, you have to continue to ask yourself, “What do I believe will be sustainable for my lifestyle?” and “Which eating style will have me at my best?” — not just physically, but mentally and emotionally as well.

Adele Jackson-Gibson Senior Editor Adele Jackson-Gibson is a certified fitness coach, model, and writer based in Brooklyn.

Intermittent Fasting on Keto: What to Know Before Combining the Diets for Weight Loss

Cutting carbs and fueling the body with fat is only gaining steam. But if you’re someone who’s found weight loss success using this popular approach, called the ketogenic diet (or keto for short), you may be thinking of taking things up a notch and combining keto with intermittent fasting to bust through a plateau or improve your results. Is this something you should try?

The short answer is maybe, though you should know up front that this combined approach hasn’t been studied or proven to work for weight loss. Experts say it could make sense, though the lack of research means you may want to think twice before delving into this eating approach.

Combining the two diets gained popularity when intermittent fasting expert Jason Fung, MD, author of The Obesity Code, recommended using keto as a foundation with fasting, explains Lori Shemek, PhD, a nutrition and weight loss expert in Dallas and author of How to Fight FATflammation. Celebs, like Halle Berry, are also said to use the diet, says Dr. Shemek.

Let’s talk about what each diet is.

What Are the Basics of the Ketogenic Diet?

Scientists originally designed a keto diet in the ’20s to help control seizures in children with epilepsy, previous research shows. This version, called the “classic” ketogenic diet or the “long-chain triglyceride diet” calls for eating 3 to 4 grams (g) of fat for every 1 g of carbs and protein, according to the Epilepsy Foundation.

The version of keto many are using for weight loss today is a little different in that it is a high-fat, moderate-protein, and very-low-carb plan. Fat comprises about 80 percent of your daily calories, and you’ll aim to consume between 20 and 50 g of net carbs (carbs minus fiber) each day depending on your personal needs.

A typical keto diet food list calls for ditching most carbs, even healthy foods such as fiber-rich whole grains and most fruits, while prioritizing fats, such as avocado, olive oil, grass-fed beef, and even bacon occasionally.

The idea with this eating plan is to transition your body from one that burns glucose (or carbs) for fuel to one that relies on fat for energy. This state is called ketosis or being keto-adapted.

The keto diet can undoubtedly lead to quick weight loss in the short term. Nonetheless, critics point out that long-term research (more than two years) on people using keto for weight loss is lacking.

Also important to note is that many of the claims that keto can treat health conditions other than epilepsy — such as cancer, high blood pressure, polycystic ovary syndrome (PCOS), diabetes, and neurological diseases like Alzheimer’s disease — need more research, per a review published in August 2013 in the European Journal of Clinical Nutrition.

RELATED: 11 Health Conditions Keto May Help — and 6 It Won’t

How Does Intermittent Fasting Work?

Intermittent fasting is another diet approach where you plan specific times when you are not eating. There are several ways to do intermittent fasting, which some people simply call IF.

For instance, some people may follow the popular 5:2 IF, where five days are “normal” eating and two are extremely low-calorie (like around 500) “fast” days. Others may not eat for a 24-hour period. While others may practice time-restricted eating, such as eating for 8 hours and fasting for 16.

When it comes to IF, there’s some exciting research on humans that’s emerging, including the role that the approach may play in treating obesity and insulin resistance (the hallmark of type 2 diabetes), according to a review published in March 2017 in the journal Behavioral Sciences. Yet the authors of that review concluded that there’s “a lack of high-quality evidence” on the health effects of IF and that it’s still unclear which type of IF is best to follow.

So far, most of the studies of IF (for weight loss or otherwise) have been in animals, not humans, or have been short term.

RELATED: Answers to 15 Burning Questions About the Keto Diet

Why Combining Intermittent Fasting With Keto Has Become Popular for Weight Loss

Doing keto or IF can help with weight loss in the short term, though each diet is very restrictive, so they certainly aren’t for everyone.

But how about combining them? Could two be better than one?

First, in some experts’ view, it does make sense to pair the two approaches. The keto diet increases levels of ketones in the body; during times of fasting, ketones are also increased. “The brain will rely less on glucose for energy when in a state of nutritional ketosis. Therefore, the transition into a fasted (ketogenic) state during the day eventually becomes seamless after eating low-carb or ketogenic for a few weeks,” says Dominic D’Agostino, PhD, associate professor at the University of South Florida in Tampa and founder of

This is a strategy that practitioners counsel patients on at the Cleveland Clinic’s Functional Ketogenics Program. “Adding intermittent fasting can take things up to the next level,” says the Clinic’s Logan Kwasnicka, a certified physician assistant at the Cleveland Clinic in Ohio. That next level may be overcoming a weight loss plateau, as people may eat fewer calories when doing IF. It can also be a natural progression from a keto diet for those who feel satiated eating so much fat (ketosis may also decrease appetite) and aren’t bothered by shrinking their eating window.

RELATED: 8 Steps Beginners Should Take Before Trying the Keto Diet

Who Should Try an Intermittent Fasting Keto Approach?

Anyone who has been on keto for more than two weeks and — with the okay from their healthcare team — would like to add IF may do so. But the keto diet has become popular for those who have prediabetes or diabetes, though “asking these patients not to eat for a significant amount of time can be dangerous,” says Kwasnicka. If you have chronic kidney disease, a history of eating disorders, are undergoing active cancer treatment, or are pregnant or breastfeeding, it’s unlikely you’re a good candidate for this combined diet plan. Even the individual diets (keto and IF) may not be recommended for these populations. Check with your healthcare team.

Also, if you’re currently following the keto diet and are happy and feel good with the way you’re eating, you do not have to add in IF, she says.

RELATED: What Are the Different Types of the Ketogenic Diet, and Which Is Right for You?

The Right Way to Start an Intermittent Fasting Keto Diet

At the Cleveland Clinic, practitioners do not advise people to start both keto and IF at the same time. “It’s a huge shock to your system to switch from glucose as fuel to ketones, and implementing IF is a significant change,” says Kwasnicka. For that reason, people would start with keto. After being on the diet for a couple weeks to months, they might consider IF.

It’s also important to choose the correct timing. For their patients, Kwasnicka suggests a 12- to 16-hour fast. For many people, not eating 12 hours a day (say overnight from 7 p.m. to 7 a.m.) is a natural habit anyway and doesn’t require skipping meals.

To start, consider delaying breakfast (starting with an hour and then slowly extending the time) to get your body accustomed to going longer stretches without eating, suggests Shemek. When you’ve adjusted to your new eating pattern, reintroduce breakfast earlier in the day and extend your overnight fasting time, as eating breakfast not only leads to better cognition, but also improved metabolism and insulin sensitivity, according to a study published in August 2018 in the American Journal of Physiology-Endocrinology Metabolism. As for the length of time to stay on keto-IF, she recommends doing keto-IF for no more than six months and then transitioning to a more standard low-carb diet.

RELATED: 10 Popular Low-Carb Diets, and Their Pros and Cons

A Sample Menu for Keto and Intermittent Fasting

If you’ve gotten the green light from your healthcare team and want to try this combined approach, you might be wondering what you’ll eat (and when). Your instincts are right: This diet is all about the timing.

Below, here’s what Shemek says three days on the plan might look like when done with time-restricted eating in a 16-hour fast, 8-hour feed pattern. This approach isn’t the only way to do IF — there are many ways to fast. For example, you can also do a 12- or 14-hour daily fast.

In this plan, you’ll see that snacks are optional. Also keep in mind that your carb, protein, and fat needs to stay in ketosis depend on your individual health. Working with a registered dietitian familiar with keto-IF can help you determine those ratios.

Day 1

10 a.m. Black coffee and scrambled eggs topped with avocado slices; water all morning

1 p.m. Lunch Large leafy green salad topped with 2 tablespoons (tbsp) of olive oil, vinegar, and 3 ounces (oz) grilled salmon

3 p.m. Snack (optional) ¼ cup Macadamia nuts

6 p.m. Dinner Chicken leg (with skin), ¼ cup of cooked wild rice, and 2 cups of zucchini cooked with olive oil

Day 2

10 a.m. Plain hot tea, a keto-friendly smoothie, water all morning

1 p.m. Lunch 3 oz grilled chicken breast, half a plate filled with broccoli and cauliflower drizzled with 1 tbsp olive oil, 1 whole avocado

3 p.m. Snack (optional) Unsweetened coconut chips

6 p.m. Dinner 3 oz seared tuna cooked in olive oil on a bed of Asian coleslaw, topped with a drizzle of olive oil and sesame seeds

Day 3

10 a.m. Black coffee with keto chia pudding; water all morning

1 p.m. Lunch 3 egg omelet stuffed with peppers (½ whole pepper) and spinach (1 cup) cooked in 1 tbsp olive oil, topped with ½ an avocado, side of ½ cup sliced tomatoes

3 p.m. Snack (optional) Olives

6 p.m. Large kale salad (3 cups) with 3 oz shrimp drizzled with 2 tbsp of olive oil and vinegar of your choice

RELATED: What Are the Best and Worst Fats to Eat on the Ketogenic Diet?

The Possible Health Benefits of a Keto Intermittent Fasting Diet

There isn’t research on the health effects of doing keto and IF together, but it’s clear that ketone levels increase when the plans are combined. This may help accelerate weight loss, says Dr. D’Agostino. Still, everyone responds differently, so this may not be true across the board, he says.

Shemek has all of her clients use keto or the IF and keto combo. “My clients are typically all prediabetic and overweight. Once they see and feel what eating in this way does for them — including regulating their blood sugar levels — they are able to stay on an IF and keto plan easily. The success of the combined approach reinforces their committment,” she says.

One interesting way that low-carb IF diets are being studied outside of weight loss is for cognitive health. Richard Isaacson, MD, director of the Alzheimer’s Prevention Clinic at Weill Cornell Medicine and NewYork–Presbyterian in New York City, says that doing a low-carb, time-restricted IF may be beneficial for “calming down insulin pathways and letting the brain benefit from cleaner burning fuel,” which may offer benefits for people with Alzheimer’s disease.

In fact, Dr. Isaacson personally does an 8-hour feed, 16-hour fast four to five days a week. This strategy, he says, may also help limit fat accumulation around your waist. “A bigger belly mean a smaller memory center in the brain,” he says. Not to mention, more visceral (belly) fat is associated with a higher risk of chronic ailments such as heart disease and type 2 diabetes, according to an article published in January 2012 in the British Journal of Radiology.

Are There Any Known Health Risks of Doing Keto and Intermittent Fasting Together?

As for long-term risks, “people with seizure disorders (what keto was developed to treat) have been on the ketogenic diet for decades and demonstrate excellent health,” D’Agostino says. Though, like any diet, it all depends on what foods you’re eating. A keto diet rich in bacon and butter is different from one rich in avocado and olive oil, and poorly planned keto can lead to nutritional deficiencies. Because adding IF may make you cut calories too drastically, you may also lose too much weight or lean mass (muscle) if you take the restriction to the extreme. To maintain muscle mass, he recommends consuming 1 g per kilogram of body weight in protein every day.

RELATED: What Is Keto Cycling, and Is It the Key to Success on the Keto Diet?

The Bottom Line on Combining the Keto Diet With Intermittent Fasting

The keto diet is a restrictive high-fat diet, and intermittent fasting restricts the number of hours you will be eating. There is a lack of research on each diet alone, along with this combined plan, so it’s unclear exactly what you’re getting into if you try them individually or together.

If you decide to give the diets a go, know that they are extremely restrictive, so it may be difficult to stick with the low carb count and confined eating window. (Even children who follow keto to help control epilepsy have a hard time adhering to the plan!)

Before deciding to follow keto and IF together, be sure to consult your healthcare team. Your provider can help you determine whether this combined diet plan is a good fit for you, and then they can help you adjust any meds you’re on to help increase your chances for success in the safest way possible.

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You’re on the keto diet and loving the results you see. But you can’t help but wonder if you can give your weight loss even more of a boost by trying another intriguing diet regimen in tandem—intermittent fasting (IF). IF is basically a weight loss plan in which you avoid eating for periods of time—on alternate days, for instance, or more popularly, through time-restricted eating, where you schedule all your your meals into a daily time window—say, 7 a.m. to 3 p.m., or carefully spread between 7 a.m. and 7 p.m. (It’s also sometimes known as the OMAD diet, or “one meal a day.”) The question is, the combination of keto and intermittent fasting safe?

“The most important thing is to make sure you’re meeting your nutritional needs,” says Ginger Hultin, a Seattle-based registered dietitian, spokesperson for the Academy of Nutrition and Dietetics and owner of ChampagneNutrition. “That means working with a medical team.” If your doctor does sign off, how exactly does an IF-keto regimen work—and what are its true benefits? Let’s take a closer look.

How the keto diet and intermittent fasting work individually

If you’re not familiar with the principles of the keto diet, here’s what you need to know. “The ketogenic diet is very low carb—carbs are limited to 40-60 grams per day, and more than 80% of your calories come from fat,” Hultin explains. “Keto is a moderate protein diet—it’s designed to force the body into a fat-burning state called ‘ketosis’. Ketosis uses an energy source called ketone bodies to fuel the brain. So your body is forced to break down fat rather than using glucose, or blood sugar, for fuel. When the glucose in your body is depleted, ketone bodies are created. Then, those ketone bodies cross your blood/brain barrier as energy for your brain and central nervous system.”

Intermittent fasting is built around a more simple concept: good old-fashioned calorie restriction. “Intermittent fasting can be done in a variety of ways,” Hultin says. “The overall foundation, though, is based on a period of extended time where you go without eating—a fast. Many people on IF do this for 12-16 hours overnight, and eat their first meal at lunch or mid-morning.” Not only are calories cut back this way, but “IF proponents believe that this schedule helps with digestion, too.” Hultin adds. And it seems to be highly effective: a recent overview of research on intermittent fasting found that as a whole, if you’re in good physical and emotional health, this kind of plan on its own won’t hurt you. Indeed, almost any intermittent fasting plan is going to result in some level of weigh loss, too, according to the overview’s authors.

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Load up on Vitamin E when you’re sick. Vitamin E is a powerful antioxidant that helps the body fight off infection. Find it in nuts, seeds and spinach. From Our Partners at the Cleveland Clinic

What are the benefits of intermittent fasting and keto together?

If you work IF into your keto plan, one big plus you may notice is that you reach ketosis faster. Why? Fasting causes your body to move its fuel reserve away from carbs and onto fats, which is, of course, the same way keto causes you to lose weight. Plus, your body burns fat for energy when you fast—another keto-friendly concept. It usually takes a couple of days for your body to start kicking into weight loss mode on keto, so conceivably, intermittent fasting could give you a leg up on dropping some pounds out of the gate.

Related: 150+ Approved Foods for the Keto Diet

Is it safe to combine keto and intermittent fasting?

“It really depends on the person,” says Hultin. “For example, if you take certain medications, fasting may not be safe. If you have blood sugar problems or are on blood sugar lowering medications, either one of these diets could be extremely dangerous or even deadly.”

Obviously, if you’re pregnant, any form of weight loss diet will not be right for you. Likewise, if you have other chronic conditions, you need to abstain, period, if your doctor tells you to.

It’s also key to talk to your doctor about how the specifics of keto could interact with IF—if you currently take the cheat day, for instance. A study from the University of British Columbia found that the simple act of taking advantage of a cheat day while on keto could mean you consume as little as 75 grams of glucose and potentially damage your blood vessels. Sugar and high-fat, low-carb could make for a dangerous mix, first and foremost. Toss in further calorie restriction, and things could get a little complicated in terms of the specifics of your long-term health. Your best bet: have a physical to get a baseline profile of your health status before putting IF and keto together.

Related: Secrets From Dr. Oz—Why He’s Fasting and Using the Clock to Slow Dementia

How do you combine intermittent fasting and keto?

Here are some tips on how to get the most out of your IF-keto regimen.

Know your overall objective.

“Focus on meeting your caloric needs to stay healthy,” stresses Hultin. “You need to make sure you’re getting the right amount of protein spaced throughout the period of time that you are eating on IF, because there are limits to how much protein the body can absorb and utilize at a given time. You also have to ensure that your vitamins and minerals are being met as well. You’ll also need to consider how much fiber and fluids you need, and factor that in.”

Related: Yes, You Can Be a Vegan and Do Keto! We’ve Got All the Best How-To Tips

Go slowly.

A new study from Johns Hopkins suggests that intermittent fasting could be part of a healthy lifestyle, but that physicians advise patients to gradually increase the duration and frequency of the fasting periods over the course of several months, instead of “going cold turkey.”

Eat earlier.

Restrict the hours of the day when you eat to between 7 a.m. to 3 pm, or 10 a.m. to 6 p.m. It’s better to fast closer to bedtime.

Consult a dietitian.

Combining two plans like IF and keto is often most successful when you work with a pro. “People underestimate how critical having a dietitian on their team can be,” Hultin says. “We really know the ins and outs of keeping people safe, and meeting their needs can be a game changer. A registered dietitian or nutritionist can help you avoid eating disorder behavior, discuss your body image and relationship to food, and help you get on a balanced dietary pattern that you can stick with long term—but still helps you meet your health goals.”

Try these tips to avoid the keto flu and other side effects.

How to Do Intermittent Fasting for Weight Loss

  • Research shows intermittent fasting to be a powerful tool for helping you reach and maintain a healthy weight.
  • Learn how intermittent fasting works with your body to rewire your metabolism — and deliver additional health benefits, too.
  • Find the type of intermittent fasting that’s right for you, and learn what to eat between periods of fasting in order to maximize your results.
  • Want to fast without feeling hangry? Bulletproof Intermittent Fasting delivers the benefits of fasting and curbs the hunger cravings that can take you off track.

Fasting means you aren’t eating for an extended period of time. If you think about it, fasting isn’t all that unnatural. Your ancestors evolved to thrive in situations when food was scarce. Intermittent fasting — cycling in and out periods of fasting and eating — is a simple eating plan that makes the most of your body’s own fat-burning systems. Research shows that intermittent fasting is a proven way to help people lose weight.

In a Bulletproof Radio podcast episode, Dr. Sylvia Tara, PhD, author of “The Secret Life of Fat,” said starting the routine is hardest part of intermittent fasting — but after six to eight weeks, she didn’t feel the same food cravings. Her advice for weight loss with intermittent fasting? “For people who have those 20 pounds, know, number one, it can be done. Number two, it might be a bit more effort than you thought it was going to be… Third, know that it gets easier with time and you can maintain it. It really isn’t as bad once you get into it, and it’s extraordinarily effective.”

Intermittent fasting also offers big benefits for your body and brain. It can ward off chronic disease, help your body work better and improve your mood. Read on for the science behind intermittent fasting and weight loss, plus tips to maximize your fast.

How weight loss works with intermittent fasting

When you’re intermittent fasting, you eat all the food your body needs, but during a shorter period of time. There are many methods, but the most common involves eating during a six- to eight-hour window and fasting the remaining 14 to 16 hours. It’s not as bad as it sounds, especially when you add Bulletproof Coffee to keep hunger levels in check (more on that later).

Intermittent fasting triggers a perfect storm of metabolic changes to tackle weight loss and fat reduction. How does it work?

  • Reduces calories: If you’re a snacker or tend to grab food on the go, you may be eating more calories than your body needs — and that will show up on the scale. In general, you tend to eat less when you limit the amount of time you can eat during the day.
  • Kickstarts ketosis: Intermittent fasting is a pathway to the fat-burning state of ketosis. During your fast, your body burns through its glucose reserves (aka carbohydrates) for energy. Then, you start burning fat for fuel. To maximize weight loss, eat a ketogenic diet between periods of fasting. Learn more about the keto diet here.
  • Lowers insulin levels: Intermittent fasting affects insulin in two ways. First, your body becomes more sensitive to insulin, which can help prevent weight gain and reduce your risk of diabetes. Second, fasting decreases your insulin levels, which can cue your body to start burning stored fat instead of glucose.
  • Boosts metabolism: In rodent studies, intermittent fasting reprogrammed metabolic pathways to get more energy out of food. Fasting also increases your levels of adrenaline and noradrenaline, hormones that help your body free up more stored energy (that’s your body fat) during a fast. Boosting your resting metabolism helps your body burn more calories throughout the day, even while you rest. Get the details on ways to boost your metabolism.

Multiple studies show that intermittent fasting accelerates weight loss. In a 2015 review pooling 40 different studies, participants shed 10 pounds in a 10-week period on average. Another smaller study of 16 obese adults following an “alternate day” intermittent fasting schedule (eating 25 percent of their daily calories on one day, and eating normally the following day) resulted in them losing up to 13 pounds over 8 weeks.

Intermittent fasting also succeeds where many weight-loss regimes fail: by targeting and reducing visceral fat. Visceral fat is the stubborn, internal fat packed deep around your abdominal organs. During a period of six months, people on an intermittent fasting diet were able to shed four to seven percent of their visceral fat.

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Additional benefits of intermittent fasting

Intermittent fasting isn’t just about achieving a healthy weight. Here are some additional benefits you’ll experience along the way:

  • Improves cardiovascular health: Intermittent fasting diets have been shown to improve cholesterol, improve blood pressure and reduce cardiovascular risk. One note: These studies associate intermittent fasting with lower levels of LDL and VLDL cholesterol. Here’s why managing your inflammation might be more important .
  • Reduces inflammation: According to early research (read: rodent studies and small human sample sizes), lowering inflammation may be the key to maintaining a healthy weight, boosting longevity and reducing your risk of major illnesses. That’s why anti-inflammatory foods are at the core of the Bulletproof Diet. Intermittent fasting decreases oxidative stress and inflammation across the board, including inflammatory markers such as adiponectin, leptin and brain-derived neurotrophic factor (BDNF).
  • Helps remove cellular waste: Over time, your cells naturally accumulate damaged cells and waste — junk that can interfere with cellular function. In rodent studies, intermittent fasting has been shown to promote a process called autophagy, which is what happens when your body clears out the cellular junk so your body can work even better.
  • Supports healthy aging: Studies show that intermittent fasting can help protect your cardiovascular system and how you manage blood sugar to support healthy aging. It even helps promote feelings of tranquility and alertness. In rodent studies, intermittent fasting has been shown to increase lifespan and protect against disease.

How to start intermittent fasting

There is more than one way to start intermittent fasting, which is great because every BODY is different. The key is to experiment and listen to your body to see what works best for you. Here are some of the ways to get started:

  • 16:8: You eat all of your daily calories within a shortened period (typically 6-8 hours) and fast the rest of the time.
  • Bulletproof Intermittent Fasting: Similar to 16:8, but with one crucial difference so you don’t get hangry: You drink a cup of Bulletproof Coffee in the morning. The quality fats keep you full until lunch, and you remain in a fasted state so you reap all the benefits of intermittent fasting. And don’t worry — Bulletproof Coffee won’t break your fast.
  • One meal a day (OMAD): Also known as eating once a day. You eat all of your daily calories in just one meal each day, and fast the rest of the day.
  • 5:2: You eat normally five days a week. On the other two days, you “fast” by eating between 500 and 600 calories.
  • Alternate Day Fasting: You alternate a day of eating normally with a day eating 25 percent of your typical daily calories. A study found that obese adults following an “alternate day” intermittent fasting schedule lost up to 13 pounds over 8 weeks.

Related: Want to Try a Fasting Diet? How to Choose the Right One

If intermittent fasting causes fatigue or other negative symptoms, try fasting just once or twice a week, and build up from there. As with any diet or exercise plan, consult your healthcare provider to determine what’s best for you.

Tips for intermittent fasting for weight loss

It’s not easy to resist the cravings, but there are some easy ways to avoid feeling hungry that can also help you get even more out of your fast:

Don’t skip breakfast

We know — going without your morning meal can be hard. So, instead of skipping breakfast, enjoy a creamy cup of satisfying Bulletproof Coffee. This simple hack keeps you in a fasted state and keeps the “hangries” away while nourishing your body with good fats.

Eat the right fats

The ultimate hack for your intermittent fast: Bulletproof Brain Octane MCT oil and XCT oil. They’re MCT oils, but better. Your body turns MCTs into ketones, which help burn fat, curb cravings and power your brain with more energy, better mental performance and fewer cravings.

Cut back on carbs

Follow the Bulletproof Diet during your eating periods to supercharge the impact of intermittent fasting. Restricting carbohydrates will decrease your appetite (bye cravings!) and make it easier for your body to shift into fat-burning ketosis.

Plan meals ahead of time

When it’s time to eat, those sweets and snacks start looking mighty tempting. To avoid binging on carbs or junk food, prepare healthy options ahead of time with the right fats, high-quality meats and vegetables. These keto meal prep recipes will help you stay on track.

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  • Before and after

    Christine has completely transformed her health in only one year with a keto diet and intermittent fasting. Here she shares all the benefits and what it has been like ditching carbs:

    Dear Dr. Eenfeldt,

    I never in a million years thought that I would share my story, but after a very emotional weekend looking at this year-old picture, and lots of encouragement, I am sending it along.

    The picture I am sending is one year apart – from a very unhealthy, metabolically sick 49-year old transformed to a healthy, energetic 50-year old. I am completely blown away by the changes.

    In October 2016, I had been on a “quitting sugar” journey for a few months and had successfully given up the white, sweet stuff. Desserts, cookies, and packaged foods were no longer part of my diet but was resulting in a very slow weight loss. I started this journey to lose weight, and to reverse metabolic syndrome, fatty liver, insulin resistance, and if I was very lucky, sleep apnea.

    I was complaining about the slow loss to a friend and she asked me if I was familiar with the work of Dr. Fung. I had never heard of him or of the LCHF/keto way of eating. On that day, January 13, 2017, I came home and scoured the internet for info. The first source of information was your wonderful website. I spent ALL weekend on your website just soaking it all in. I truly appreciate all the educational videos and the testimonials. January 13, 2017 was the last day I ate potatoes, bread, and pasta. Those were the final high-carb foods that I kicked to the curb – and as a result, I had excellent results with weight loss. Because I had already quit sugar, there was little difficulty or withdrawal – I’m pretty sure I entered a ketosis state within a week of ditching those high-starchy carbs.

    Nine months on the LCHF/Keto and intermittent fasting journey, I have dropped over 80 lbs (36 kg) and am so very close to a healthy weight. I have also lost: daily headaches, monthly migraines, cystic acne, ovarian cysts, lethargic afternoons and evenings, joint pain, inflammation, and best of all sleep apnea – I no longer have to use a CPAP machine (confirmed with another sleep test that my obstructive sleep apnea is gone!). I have gained: a renewed joy for life, more energy than I know what to do with, a new appreciation for real food and cooking, shopping in regular size shops, improved self-esteem that has allowed me to be willing to put myself out there in ways I never dreamed of, and a sincere passion to share this way of life with anyone who asks me!

    Turning 50 has been the best thing that has ever happened to me because it really lit a fire in caring for my personal health. My biggest challenge was letting go of potato chips – but repeating a question to myself as to what those (and other carby foods) would do to my insulin response, I was able to break that addiction and have no desire for those foods that obviously make me sick.

    My biggest regret is not knowing about this way of life earlier, but I truly believe God’s hand was in this journey with me every step of the way – making it easy to adopt this new lifestyle to stick with it 100%. I am so very grateful for real food and your website – it has truly given me the gift of LIFE to enjoy with my family and friends for many years to come. Here’s to the next 50 years! God bless you and your work!


    We’re so glad that we’ve been able to help you on your way to better health, Christine! You look radiant 🙂

    Christine’s webpage

    Joyful Keto Life

    Get started

    Do you want to try what Christine has done? Sign up for our free 2-week keto low-carb challenge!

    Alternatively, use our free keto low-carb guide, or for maximum simplicity try out our new low-carb meal planner service – it’s free to use for a month.

    At this point, you probably know all about the keto diet—if you’re not currently on it, you probably know someone who’s tried it, or maybe you’ve dabbled in the high-fat, low-carb diet just to see what all the fuss is about. And if you’re super into diet trends, you might even know about intermittent fasting (IF), a method of eating that requires you to fast for a set number of uninterrupted hours per day.

    But here’s one trend you may not know a lot about: doing IF and keto at the same time. Whoa. As if one diet wasn’t hard enough, are there really people out there tackling two diets at once?

    Yup. And keto proponents claim good reasons for doing it, too—some of which could be legit.

    “Practicing IF while on the keto diet may help the body reach ketosis faster,” says registered dietitian Danielle Schaub, culinary and nutrition manager for Territory Foods. “Because both IF and the keto diet are based on the beneficial shift toward burning body fat instead of carbs for energy, similar health goals can be accomplished by both.”

    Now for the really important questions: How do you actually do IF and keto together? Does it help you lose more weight? Do you end up with double the side effects? And, finally, is it really a good idea? Here’s everything you need to know about combining keto and intermittent fasting.

    First, what exactly is keto?

    Keto is a high fat, low-carb diet often mistaken for a high protein diet because so many of its popular recipes include bacon and other types of animal meat, but the focus really is on fat. Some people even do a vegetarian version of keto, chowing down on healthy fat sources like olive or coconut oil, nuts and seeds, avocados, and dairy products (while avoiding greasy cheeseburgers and sirloin steaks).

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    The goal of the keto diet is to eat meals that are 60 to 75 percent fat, 15 to 30 percent protein, and 5 to 10 percent carbohydrates; doing so puts you into a state of ketosis where you can burn ketones from fat instead of glucose from carbs, speeding up your metabolism and increasing the potential for weight loss (according to the diet’s proponents).

    Ok, so what’s the deal with intermittent fasting?

    IF is a pattern of eating where you restrict foods and sweetened beverages for an uninterrupted period of time every day (usually 16 hours) and then eat only during the remaining 8 hours.

    “You can pick your windows but we encourage people to eat when the sun is up and fast when the sun is down,” says registered dietitian Amy Shapiro, founder of Real Nutrition. “During fasting hours you can drink water, black coffee or plain tea, but nothing that provides calories or requires any sort of digestion or shift in hormones.”

    The theory behind IF is that depriving your body of calories for an extended period of time forces it into a temporary state of starvation and slowed metabolism. This makes your fat cells burn glucose for energy and can lead to improved weight loss results.

    There are several different ways to schedule your fasting times, but the 16:8 version is the most commonly used.

    How can you combine keto and intermittent fasting?

    It’s actually not that hard if you’ve already got a good handle on keto, since that diet has a stronger learning curve in terms of what’s allowed. Technically IF isn’t even a “diet” in the traditional sense, says Brigid Titgemeier, RDN, a functional medicine dietitian and the founder of BeingBrigid.

    “Intermittent fasting can be paired with any kind of diet because it simply refers to the number of hours that you fast,” she explains. “Combining keto with intermittent fasting means adhering to the parameters of a ketogenic diet and eating within a condensed window of time.”

    Related Story

    For example, Titgemeier lays out the following schedule for eating within the parameters of both diets (assuming a 16-hour fast between 6 p.m. and 10 a.m.).

    7 a.m.: Green tea or black coffee

    10 a.m.: Keto macadamia bread topped with ricotta cheese and sauerkraut

    12 p.m.: 4-6 ounces of wild salmon served with a bed of sautéed greens and ½ avocado

    3 p.m.: Grainless granola with unsweetened almond yogurt

    5:30 p.m.: Shrimp bowl with 4-6 ounces of shrimp, cauliflower rice and sunflower seeds

    7 p.m.: Herbal tea

    Is keto better than IF (or vice versa)?

    It depends on your nutrition goals, says Shapiro, but she doesn’t recommend keto for the majority of people because of its restrictive nature (there are some people with health conditions, like epilepsy, who may benefit from a ketogenic diet).

    IF, though, is a different story: “I recommend 12 to 14 hour IF for most individuals because it helps to break mindless eating patterns, encourages balanced meals, and allows for proper digestion, better sleep, and hormone balance,” Shapiro says.

    Schaub agrees, saying that “in general, intermittent fasting is safer and more in line with a natural way of eating, can be practiced for long periods of time.”

    In other words, IF is a more flexible way of eating that often fits organically into a person’s lifestyle (which also makes it easier to stick with long-term). Keto, on the other hand, may be too restrictive to be sustainable—or healthy. Because it’s a medical diet, it carries risks of nutritional deficiencies as well as liver and kidney problems, per Harvard Health.

    Can combining keto and intermittent fasting help me lose weight?

    There’s some solid consensus among the RDs: combining keto with IF does help you reach ketosis faster, which may lead to additional weight loss.

    “IF paired with keto intensifies the effects of the ketogenic diet, since they both increase the ketones in the blood,” says Titgemeier. Since the time it takes to enter into ketosis differs from person to person (leaving you suffering from the keto flu in the meantime), anything that can make that happen sooner is appealing to keto dieters…even if it means piling yet another diet on top of the one they’re already doing.

    Related Story

    Additionally, Shapiro says that grouping your meals into a shorter window of non-fasting may allow your body to burn its energy stores instead of continuing to build them up—something which could cause more fat loss than if you did only keto or IF.

    “Eating heavy meals and then letting your body digest will allow for weight loss and hormone balance as well as time for our bodies to use the nutrients we are ingesting for energy,” she explains.

    Are there any side effects to combining keto and intermittent fasting?

    WH has previously reported on the many gag-inducing side effects of going keto (constipation and diarrhea and hair loss, oh my!), and the potential downsides of IF, which include low blood sugar, fatigue, nausea, and being just plain hangry all the time.

    So do you end up with double the side effects when you combine the diets? In theory, yes. Putting the two together doesn’t do anything to counteract the side effects of either diet, so you could wind up with the undesirable combination of nausea and constipation (or hair loss and hanger, or…well, you get the idea).

    Related Story

    More importantly, though, the biggest downside to pairing keto with IF is the sheer level of commitment involved—and the high potential for failure.

    “It’s very difficult to maintain such a narrow way of eating,” says Schaub. “Eating an extremely high-fat, low-carb diet itself is difficult to do while maintaining a social life and flexibility in your schedule; layer in a restricted eating window of eight hours, and the ability to sustain it becomes that much tougher.”

    The one plus side? Schaub does say that IF could become less uncomfortable when coupled with keto: “The ketogenic diet is very satiating—eating fat leads to less hunger overall, which makes restricting your eating window significantly easier.”

    Finally, while IF is a more natural way of eating, keto is decidedly stricter/not for everyone (and definitely not for kids, pregnant women, people with a disordered history of eating, high-intensity athletes, or people with certain health conditions).

    “Consult a dietitian or other healthcare practitioner if you are considering following a ketogenic diet paired with intermittent fasting,” says Titgemeier. “You may want to start with intermittent fasting first to see how you feel before going full force with both intermittent fasting and keto.”

    The bottom line: There may be additional weight loss benefits to doing both the keto and intermittent fasting diets together instead of alone…but it may be hard to stick with both long enough to reap any benefits.

    Sarah Bradley Sarah Bradley is a freelancer writer from Connecticut, where she lives with her husband and three sons.

    The topics of ketosis and intermittent fasting are closely related and often fall within the same conversation. That’s because fasting can be a useful practice to help you reach ketosis. But is there such a thing as keto intermittent fasting?

    Just as intense and prolonged exercise (particularly HIIT training or lifting weights) may help induce a ketogenic state, intermittent fasting can help you enter ketosis faster than following a keto diet alone.

    There are many more overlaps between intermittent fasting and a low-carb diet, which you’ll learn about in this guide.

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    What Is Ketosis?

    Ketosis is the process of burning ketone bodies for energy.

    On a regular diet, your body burns glucose as its primary fuel source. Excess glucose is stored as glycogen. When your body is deprived of glucose (due to exercise, intermittent fasting, or a ketogenic diet), it will turn to glycogen for energy. Only after glycogen is depleted will your body start burning fat.

    A ketogenic diet, which is a low-carb, high-fat diet, creates a metabolic shift that allows your body to break down fat into ketone bodies in the liver for energy. There are three main ketone bodies found in your blood, urine, and breath:

    • Acetoacetate: The first ketone to be created. It can either be converted into beta-hydroxybutyrate or turned into acetone.
    • Acetone: Created spontaneously from the breakdown of acetoacetate. It’s the most volatile ketone and is often detectable in the breath when someone first goes into ketosis.
    • Beta-hydroxybutyrate (BHB): This is the ketone that’s used for energy and the most abundant in your blood once you’re fully in ketosis. It’s also the type found in exogenous ketones and what ketogenic blood tests measure.

    Intermittent Fasting and Its Relation to Ketosis

    Intermittent fasting consists of eating only within a specific period of time and not eating for the remaining hours of the day. Every person, whether they’re aware of it or not, fasts overnight from dinner to breakfast.

    The benefits of fasting have been used for thousands of years in Ayurveda and Traditional Chinese Medicine as a way to help reset your metabolism and help your gastrointestinal system after overeating.

    There are many approaches to intermittent fasting, with different time frames:

    • 16-20 hours fasting period
    • Alternate-day fasting
    • 24-hour day fasting

    If you want to start fasting, one popular version is the 16/8 keto intermittent fasting method, where you eat within an 8-hour eating window (for example, 11 a.m. to 7 p.m.), followed by a 16-hour fasting window.

    Other fasting schedules include the 20/4 or 14/10 methods, while some people prefer doing a full 24-hour fasting day once or twice per week.

    Intermittent fasting can put you in a state of ketosis faster because your cells will quickly consume your glycogen stores, and then start using your stored fat for fuel. This leads to an acceleration of the fat-burning process and increased ketone levels.

    Ketosis vs. Intermittent Fasting: Physical Benefits

    Both the keto diet and intermittent fasting can be effective tools for:

    • Healthy weight loss
    • Fat loss, not muscle loss
    • Balancing cholesterol levels
    • Improving insulin sensitivity
    • Keeping blood sugar levels stable

    Keto for Weight Loss, Fat Loss and Improved Cholesterol

    The keto diet drastically decreases your carb intake, forcing your body to burn fat rather than glucose. This makes it an effective tool not only for weight loss, but also for the management of diabetes, insulin resistance, and even heart disease.

    While individual results vary, keto has consistently led to a reduction in weight and body fat percentage in a wide range of situations.

    In a 2017 study, participants who followed a low-carbohydrate keto meal plan significantly decreased body weight, body fat percentage, and fat mass, losing an average of 7.6 pounds and 2.6% body fat while maintaining lean muscle mass.

    Similarly, a 2004 study observing the long-term effects of a keto diet in obese people found that their weight and body mass decreased dramatically over the course of two years. Those who drastically reduced their carbohydrate intake saw a significant decrease in LDL (bad) cholesterol, triglycerides, and improved insulin sensitivity.

    In 2012, a study compared a ketogenic diet to eating fewer calories in obese children and adults. The results showed children following the keto diet lost significantly more body weight, fat mass, and total waist circumference. They also showed a dramatic decrease in insulin levels, a biomarker of type 2 diabetes.

    Intermittent Fasting for Fat Loss and Maintaining Muscle Mass

    Research has shown that intermittent fasting can be an efficient weight loss tool, sometimes being even more useful than simply restricting your calorie intake.

    In one study, intermittent fasting was shown to be as effective as continuous calorie restriction in fighting obesity. In studies done by the NIH, weight loss was reported for over 84% of the participants — no matter which fasting schedule they chose.

    Like ketosis, intermittent fasting can promote fat loss while maintaining lean muscle mass. In one study, researchers concluded that people who fasted had better weight loss results (while preserving muscle) than those who followed a low-calorie diet, even though the total caloric intake was the same.

    Ketosis vs. Intermittent Fasting: Mental Benefits

    Beyond their physiological benefits, both intermittent fasting and ketosis provide various mental benefits. Both have been scientifically shown to:

    • Boost memory
    • Improve mental clarity and focus
    • Prevent neurological diseases including Alzheimer’s and epilepsy

    Keto for Improving Brain Fog and Memory

    On a carb-based diet, the fluctuations in your blood sugar levels can cause fluctuations in energy levels — these are known as sugar highs and sugar crashes. In ketosis, your brain uses a more consistent source of fuel: ketones from your fat stores, resulting in better productivity and mental performance.

    This is because your brain is the most energy-consuming organ in your body. When you have a clean and consistent energy supply from ketones, this can help your brain function in a more optimal way.

    On top of that, ketones are better at protecting your brain. Studies show that ketone bodies may have antioxidant properties that protect your brain cells from free radicals, oxidative stress, and damage.

    In one study performed on adults with impaired memory, the rise of BHB ketones in their blood helped improve cognition.

    If you have a hard time staying focused, your neurotransmitters may be to blame. Your brain has two main neurotransmitters: glutamate and GABA.

    Glutamate helps you form new memories, learn complicated concepts, and helps your brain cells to communicate with each other.

    GABA is what helps control glutamate. Glutamate can make your brain cells overly excited. If this happens too often, it can cause brain cells to stop working and eventually die. GABA is there to control and slow down glutamate. When GABA levels are low, glutamate reigns free and you experience mental fog.

    Ketone bodies help to prevent brain cell damage by processing excess glutamate into GABA. Since ketones increase GABA and decrease glutamate, they aid in preventing cell damage, avoiding cell death, and improving your mental focus.

    In other words, ketones help keep your GABA and glutamate levels balanced so your brain stays sharp.

    Intermittent Fasting Effects on Stress Levels and Cognitive Function

    Fasting has been shown to improve memory, reduce oxidative stress, and preserve learning capabilities.

    Scientists believe that intermittent fasting works by forcing your cells to perform better. Because your cells are under mild stress while fasting, the best cells adapt to this stress by enhancing their own ability to cope, while the weakest cells die. This process is called autophagy.

    This is similar to the stress your body undergoes when you hit the gym. Exercising is a form of stress your body endures to improve and get stronger, as long as you rest enough after your workouts. This also applies to intermittent fasting and as long as you continue to alternate between regular eating habits and fasting, it can continue to benefit you.

    All of this means the keto intermittent fasting combination is powerful and can help improve your cognitive function, thanks to the protective and energizing effects of ketones as well as the mild cellular stress caused by fasting.

    The Keto Intermittent Fasting Connection

    The ketogenic diet and intermittent fasting share many of the same health benefits because both methods can have the same result: a state of ketosis.

    Ketosis has many physical and mental benefits, from weight and fat loss to improved stress levels, brain function, and longevity.

    However, it’s important to keep in mind that if you take a milder approach to keto intermittent fasting — for example, eating within an 8-hour window — you probably won’t enter ketosis (especially if you eat a high amount of carbs during that window).

    Not everyone who tries intermittent fasting aims to enter ketosis. In fact, if someone who fasts also eats high-carb foods, there’s a very good chance they’ll never enter ketosis.

    On the other hand, if ketosis is the goal, you can use keto intermittent fasting as a tool to get there and improve your overall health.

    If you’re new to the keto world and would like some helpful tips about how to start, here are a couple of beginner’s guides to help you with your first steps:

    • Keto Fasting for Beginners: Why It’s a Good Idea
    • Keto Diet for Beginners: A Complete Guide to the Ketogenic Diet
    • The Keto Diet: A Complete Keto Diet Menu for Beginners

    If you’re not sure about what kind of dishes you can have on keto, here are a few mouth-watering recipes to add to your diet plan:

    • Keto Salted Caramel Mug Cake
    • Sugar-Free Avocado Brownie Recipe
    • MCT Oil Powder Cinnamon Smoothie

    People Are Combining Keto and Intermittent Fasting

    Getty Images

    By now, you’ve probably heard of keto, the low-carb, high-fat diet touted by celebs like Kourtney Kardashian. Chances are you’ve also heard of intermittent fasting, which involves cycling between periods of eating and fasting in order to lose weight. But should you do keto and intermittent fasting at the same time? Here’s what Tammy Lakatos Shames and Lyssie Lakatos, both registered dietitian nutritionists and creators of the Nutrition Twins, have to say about combining the two popular diets, as well as how they stack up on their own.

    What’s the Difference Between Keto and Intermittent Fasting?

    Before you delve into how the keto diet and intermittent fasting might work together, the sister duo says it’s important to first understand how they work on their own.

    “People who are truly following the keto diet — not just cutting carbs but eating less than 50 grams of carbs a day — are eating a diet that is very high in fat and very low in carbs and trying to force their body to break down fat for its main source of energy,” Tammy Lakatos Shames says, adding that this creates ketones, rather than using glucose. “So the goal of the keto diet is to achieve ketosis (and stay in ketosis), so the body is using ketones for energy.”

    RELATED: Considering the Keto Diet? Here’s Everything You Need to Know

    Intermittent fasting, on the other hand, involves going without food for a set period of time and then eating during a particular window each day. A popular method is fasting for 16 hours a day and eating in an 8-hour window each day (the 16:8 method); people also use the 5:2 method, which involves five days of normal eating matched with two days that restrict calories.

    ” are also looking to reap weight loss, metabolic and brain health benefits, as well as to reduce inflammation,” Lakatos says.

    So How Can They Work Together?

    “Since many of the benefits seen in intermittent fasting are also seen in the keto diet (weight loss, metabolic and brain benefits),” Lakatos says, “Fllowing both diets at the same time may provide additional benefits.”

    For starters, fasting encourages your body to use fat for energy rather than glucose (once it’s used up its glycogen stores) and so does the keto diet, which means “intermittent fasting may help those following the keto diet to achieve ketosis more easily,” Lakatos Shames says.

    “Research also shows that intermittent fasting increases body fat loss, which could accelerate body fat loss for those on the keto diet,” she says. “Other studies have shown that intermittent fasting may help to maintain muscle during weight loss and also be beneficial for energy levels. This may be especially helpful for those following a keto diet who are looking to lose some weight and have better exercise results.”

    RELATED: Everything You Need to Know About Intermittent Fasting

    There have also been several reported successes with combining the two, including avid keto follower Jenna Jameson, who said in an Instagram post that pairing the keto diet with intermittent fasting upped the results she was already seeing with the diet alone.

    What are the cons?

    If you’re interested in exploring concurrent keto and intermittent fasting as an option, there are some things to be aware of. Both of these diets are somewhat extreme on their own, and when coupled together need to be approached with the utmost caution.

    “Both of these diets on their own are typically difficult to follow, combine them and that adds an extra layer of challenge that may not be ideal for many people,” Lakatos says.

    You’ll want to steer clear of any diet that involves fasting if you have struggled with an eating disorder, she says; the same goes if you are pregnant or breastfeeding.

    As for the day-to-day of sticking with a combination of the keto diet and intermittent fasting, Lakatos says it can be tough to make both work.

    “Going out to eat and being social can be stressful when you have to stick to a strict regimen, and not eating during times when your friends are or not having options that you can eat can cause additional stress and lack of compliance,” she says. “Adding another layer of complexity can make living a normal lifestyle more difficult.”

    OK, So Final Word?

    The sisters say that at the end of the day, intermittent fasting and the keto diet, when done properly,” can be quite effective on their own for certain people.”

    “And for some, doing both together can reap additional benefits,” they say. “However, for many people, either diet alone is too much for them and the two together will not be a lifestyle that can work for them.”

    And, like all diets that cause an extreme shift in your food and lifestyle choices, consult your doctor beforehand.

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