What happens if you eat less than your bmr

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TDEE Calculator : Easily Calculate Your Daily Calorie Needs

TDEE – The Science Behind Weight Loss

Every day your body burns a specific number of calories just by existing. This is known as your Basal Metabolic Rate. The BMR is based on your weight, height, and age. (Calculate your BMR here)

When you exercise or simply expend energy through physical activity, you burn additional calories. When you combine your BMR with the calories you burn through physical activity, you get your Total Daily Energy Expenditure.

This is what is known as your maintenance calories. If you eat this amount of calories you will maintain your weight.

So How Do I Lose Weight?

You lose weight by having a calorie deficit.

A calorie deficit is eating less than your body needs to maintain itself and thus creating a deficit. Ever had more bills than you had money? You had a financial deficit. A calorie deficit is having less energy than you need to stay the same weight.

Let’s say that based on your age, weight, and height your BMR is 1700 calories and through some physical activity you end up with a TDEE of 2300 calories. To maintain your weight you simply eat 2300 calories every day.

To gain weight you eat more than your TDEE and to lose weight you eat less.

Of course, you can also achieve a deficit through burning more calories through exercise.

Every effective diet I’ve come across, whether it’s high fat, low fat, high carb, low carb, uses a calorie deficit to achieve weight loss.

How Many Calories Are We Talking?

Technically you can eat nothing all day and achieve weight loss through having a calorie deficit.

Many “miracle diets” claim incredible results through eating specific magical foods or using unique protocols. Unfortunately many diets out there are nothing more than glorified Crash Diets. These diets put you into severe caloric deficit resulting in, yes weight loss (usually short-term), but they can also cause health complications and damage to your metabolism.

To avoid doing damage, the general recommendation I’ve found and used is 500 calories less than your TDEE. Some people advise more, but I’ve found that to be unnecessary.

Also, having any more than a 500 calorie deficit makes it likely that along with losing fat you will lose lean muscle, which is not ideal as lean muscle helps burn additional calories.

There are 3500 calories in a pound of fat, so at 500 calories a day you will lose a pound in a week. (See how much exercise burns a pound of fat here.)

Note that your body can become conditioned to the same repeated exercise. This can affect your TDEE (see more about this).

How Do I Get Started?

I suggest that you use Macro Counting to accomplish the goal of creating a calorie deficit in order to lose weight in a healthy and sustainable way.

Counting Macros (a.k.a. flexible dieting) is non-restrictive and allows you to eat all of your favorite foods as long as they fit within your TDEE and macro goals.

You could eat unhealthy foods and still achieve weight loss (as demonstrated by The Twinkie Diet). but weight loss and health are not mutually exclusive. My advice would be to fill the majority of your diet with fresh veggies, fruits, nuts, seeds, and lean meats. This way you can feel great AND achieve weight loss.

We have a multitude of Macro tracking resources on this site, plus a comprehensive program that you can buy and get started straight away.

Don’t get bogged down by the latest and greatest research coming out of universities you’ve never heard of. All the conflicting diets and controversial advice from health gurus are enough to give anyone a headache.

Focus on your TDEE, which has proven time and time again, to be the most important tool for weight loss and getting healthier.

FAQs regarding your TDEE.

Does it Matter what you eat if you count calories?

Yes and no. Regarding weight loss, you can eat nothing but snack cakes or pizza and still lose weight if you maintain a calorie deficit. (This has been proven by several studies.) But in regards to healthy body composition and overall good health, a balanced diet is recommended. This is why we recommend tracking macros as a way to ensure that you are getting enough of each macronutrient and in turn micronutrients from ensuring that you are eating plenty of fresh vegetables and fruit.

Does TDEE include exercise?

Yes, the TDEE is your total daily energy expenditure so it should be factored to include all the movement you do in a 24 hour period. Even if you are sedentary there is still movement factored in because you are still doing activity around the house, eating, showering, running errands, etc. Don’t confuse TDEE for your REE which is your energy expenditure if you simply laid in bed all day and did absolutely nothing.

How can I calculate my calorie needs/intake?

Calculating your TDEE using the calculator above is also calculating your calories. Your TDEE is an estimation of how many calories you need in one day. Once you have your calories calculated, you can focus on reducing your calories in a way that will help you reach your fat loss goals. calculating your TDEE is one of the best ways to calculate your calories.

Just remember that whatever you decide to eat – the above information is enough for the majority of the population to get started losing weight.

How do I calculate my BMR For weight gain?

Calculating your BMR (basal metabolic rate) really isn’t a useful measure. This measurement is the calories your body uses to function absent of all movement and even digestion. Since no human exists in that context, the more accurate measure is The TDEE (total daily energy expenditure) which includes digestion and activity. Use your TDEE as the basis for calculating how much you should be eating for weight gain. Usually, adding 10% to your maintenance TDEE is a good starting place.

You’ll Love My Macro Solution Program

Step-by-step ebooks, or fully customized personal macros coaching. Now with complete vegan edition.

Ted Kallmyer is an ISSA certified Specialist in Fitness Nutrition, a Certified Fitness Trainer, and is Healthy Eater’s author and nutitional coach. If you need help reaching your weight loss/fitness goals see his personal macros coaching options. Last Updated: September 26, 2019

Can eating too little actually damage your metabolism? Exploring the truths and fallacies of ‘metabolic damage’.

There’s a lot of discussion in the fitness industry about whether crash dieting can cause metabolic damage. In this article, we’ll take on this interesting topic and separate fact from fiction. We’ll also teach you exactly why crash diets might be linked to struggling to maintain your weight in the future.

  • Want to listen instead of read?

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Despite working out consistently and intensely, plus eating carefully, you’re not losing weight (or not losing it as fast as you’d like or expect).

Or you were losing weight consistently… until recently. Now you’re stuck — even though you’re working as hard as ever.

Or when you were younger, you were super fit. Maybe you did fitness competitions. Maybe you did some crash diets. But now, even when you put in the same effort, you just can’t seem to get as lean.

“Is my metabolism damaged?”

Precision Nutrition Coaching clients ask us this question all the time.

(If you’re a health, fitness or wellness professional, you’ve probably heard it from your clients or patients too.)

Can months or years of dieting do some kind of long-term harm to the way the human body processes food?

Not exactly.

But gaining and losing fat can change the way your brain regulates your body weight.

To understand this answer let’s explore how human metabolism actually works. Then we’ll talk about whether the metabolism can actually be damaged.

Note: This post delves into the science of energy balance, thermodynamics, and metabolic regulation. If you love learning this stuff, feel free to dig in.

If, on the other hand, you’re simply looking for solid, research-backed advice on how to lose fat and break weight-loss plateaus, feel free to skip to the summary at the end.

Energy balance: The laws of physics still apply.

You need a certain amount of energy (in the form of calories) to stay alive, as well as to move around. You can get this energy from food, or you can retrieve it from stored energy (e.g. your fat tissue).

In theory:

  • If you eat less energy than you expend, you should lose weight.
  • If you do the opposite (i.e. eat more energy than you expend), you should gain weight.

In other words:

*We use the term “body stores” deliberately as it represents the tissues available for breakdown (fat, muscle, organ, bone, etc) and excludes water (which can change body weight independently of energy balance).

This relationship between ‘energy in’ and ‘energy out’ is called the Energy Balance Equation, and it’s the most commonly accepted model for calculating a person’s energy balance and how much weight they’ll lose or gain over time.

While the Energy Balance Equation determines body weight, it doesn’t tell us much about body composition, which is influenced by things like sex hormone levels, macronutrient intake (especially protein), exercise style / frequency / intensity, age, medication use, genetic predisposition, and more.

Understandably, people get really frustrated and confused with the Energy Balance Equation when the numbers don’t seem to add up, or their results don’t match their expectations. (This is a good lesson, by the way, about the importance of adjusting your expectations to match observable reality.)

And it’s a fair frustration. Most of the time, the numbers don’t add up.

Importantly:

This mismatch between expectations versus reality is not because the Energy Balance Equation is wrong, or a myth. Nobody’s body defies the laws of physics, even though it seems like that sometimes.

It’s because the equation is more complicated than it sounds.

Many factors affect the Energy Balance Equation; they aren’t mutually exclusive. What you do to ‘energy in’ affects what happens to ‘energy out’. And vice versa.

“Eat less, move more” is a good start. (Most of us could probably benefit from eating a little less and getting a little more daily activity.)

But that advice alone isn’t enough. It doesn’t take all of the complex, intersecting factors into account.

Let’s take a look at some of these factors, starting with the ‘energy in’ part of the equation.

‘Energy in’ is trickier than you think.

Reason 1: The number of calories in a meal likely doesn’t match the number of calories on the labels or menu.

This might sound hard to believe, but it’s true… the way companies (and even the government) come up with calorie and nutrient estimates is incredibly complex, rather imprecise, and centuries-old. As a result, food labels can be off by as much as 20-25 percent.

And even if those food labels were correct:

Reason 2: The amount of energy a food contains in the form of calories is not necessarily the amount of energy we absorb, store, and/or use.

Remember that the food we eat has to be digested and processed by our unique bodies. The innumerable steps involved in digestion, processing, absorption, storage, and use — as well as our own individual physiological makeup — can all change the energy balance game.

So, for instance:

  • We absorb less energy from minimally processed carbohydrates, and fats, because they’re harder to digest.
  • We absorb more energy from highly processed carbohydrates and fats, because they’re easier to digest. (Think of it this way: The more “processed” a food is, the more digestion work is already done for you.)

For example, research has shown that we absorb more fat from peanut butter than from whole peanuts. The researchers found that almost 38 percent of the fat in peanuts was excreted in the stool, rather than absorbed by the body. Whereas seemingly all of the fat in the peanut butter was absorbed.

In addition:

  • We often absorb more energy from foods that are cooked (and/or chopped, soaked, blended) because those processes break down plant and animal cells, increasing their bioavailability.

When eating raw starchy foods (like sweet potatoes), we absorb very few of the calories. After cooking, however, the starches are much more available to us, tripling the number of calories absorbed.

Interestingly, allowing starchy foods to then cool before eating them decreases the amount of calories we can extract from them again. (This is mostly due to the formation of resistant starches).

Finally:

  • We may absorb more or less energy depending on the types of bacteria in our gut.

Some people have larger populations of a Bacteroidetes (a species of bacteria), which are better at extracting calories from tough plant cell walls than other bacteria species.

Here’s an interesting example of this whole process at work. Recently, USDA researchers asked test subjects to consume 45 grams (about 1 ½ servings) of walnuts daily for three weeks.

What they found was that, on average, people only absorbed 146 of the 185 calories in the nuts. That’s 79 percent of the calorie content on the label.

In similar research, people also absorbed only 80 percent of the calories in almonds, and 95 percent of the calories in pistachios.

Beyond the average, there were individual differences: Some people absorbed more of the energy in the nuts, while some absorbed less (likely due to the differing populations of bacteria in their large intestines).

In the end, by eating a diet rich in whole, minimally processed foods, the number of calories you absorb can be significantly less than what you expect. Plus they require more calories to digest.

Conversely, you will absorb more calories by eating lots of highly processed foods, plus burn fewer calories in the digestive process. (In addition, highly processed foods are less filling, more energy dense, and more likely to cause overeating.)

Since the number of calories someone thinks they’re consuming could be off by 25 percent (or more), their carefully curated daily intake of 1,600 calories could really be 1,200… or 2,000.

This means:

As you can see, there’s a big margin of error for energy input, even if you’re a conscientious calorie counter. This doesn’t invalidate the Energy Balance Equation. It just means that if you want an accurate calculation, you probably have to live in a fancy metabolic lab.

For most people, it’s not worth the effort (that’s one reason why Precision Nutrition moved to a hand-based measuring model for portions).

‘Energy out’ varies a lot from person to person.

‘Energy out’ — again, energy burned through daily metabolism and moving you around — is a dynamic, always-changing variable.

There are four key parts to this complex system:

1. Resting metabolic rate (RMR)

RMR is the number of calories you burn each day at rest, just to breathe, think, and live. This represents roughly 60 percent of your ‘energy out’ and depends on weight, body composition, sex, age, genetic predisposition, and possibly (again) the bacterial population of your gut.

A bigger body, in general, has a higher RMR.

For instance:

  • A 150-pound man might have an RMR of 1583 calories a day.
  • A 200-pound man might have an RMR of 1905 calories.
  • A 250-pound man might have an RMR of 2164 calories.

Crucially, RMR varies up to 15 percent from person to person. If you’re that 200-pound guy with an RMR of 1905 calories, another guy just like you on the next treadmill might burn 286 more (or fewer) calories each day with no more (or less) effort.

2. Thermic effect of eating (TEE)

This may surprise you, but it takes energy to digest food. Digestion is an active metabolic process. (Ever had the “meat sweats” or felt hot after a big meal, especially one with lots of protein? That’s TEE.)

TEE is the number of calories you burn by eating, digesting, and processing your food. This represents roughly 5-10 percent of your ‘energy out’.

In general, you’ll burn more calories in your effort to digest and absorb protein (20-30 percent of its calories) and carbs (5-6 percent) than you do fats (3 percent).

And as noted before, you’ll burn more calories digesting minimally processed whole foods compared to highly processed foods.

3. Physical activity (PA)

PA is the calories you burn from purposeful exercise, such as walking, running, going to the gym, gardening, riding a bike, etc.

Obviously, how much energy you expend through PA will change depending on how much you intentionally move around.

4. Non-exercise activity thermogenesis (NEAT)

NEAT is the calories you burn through fidgeting, staying upright, and all other physical activities except purposeful exercise. This, too, varies from person to person and day to day.

This means:

Each of these is highly variable. Which means the ‘energy out’ side of the equation may be just as hard to pin down as the “energy in” side.

So, while the Energy Balance Equation sounds simple in principle, all these variables make it hard to know or control exactly how much energy you’re taking in, absorbing, burning, and storing.

Here’s the entire equation:

When you try to outsmart your body and it outsmarts you back.

Even if all the variables in the final equation above were static, the Energy Balance Equation would be complicated enough. But things get crazy when you consider that altering any one of the variables causes adjustments in other, seemingly unrelated variables.

This is a good thing, of course. Our human metabolisms evolved to keep us alive and functioning when food was scarce. One consequence:

When ‘energy in’ goes down, ‘energy out’ goes down to match it. (You burn fewer calories in response to eating less).

Not in everybody. And not perfectly. But that’s how the system is supposed to work. That’s how our bodies avoid unwanted weight loss and starvation. It’s how humans have survived for 2 million years. The body fights to maintain homeostasis.

Likewise, when ‘energy in’ goes up, ‘energy out’ tends to go up too. (You burn more calories in response to eating more).

To illustrate this point, here’s how your body tries to keep your weight steady when you take in less energy and start to lose weight*.

  • Thermic effect of eating goes down because you’re eating less.
  • Resting metabolic rate goes down because you weigh less.
  • Calories burned through Physical activity go down since you weigh less.
  • Non-exercise activity thermogenesis goes down as you eat less.
  • Calories not absorbed goes down and you absorb more of what you eat.

*This response is particularly modest at first. But the adaptation really ramps up as you lose more weight. (Or if you’re starting out lean and trying to get super-lean).

Check out what this looks like:
In addition to these tangible effects on the equation, reducing actual calories eaten also causes hunger signals to increase, causing us to crave (and maybe eat) more.

The net effect leads to a much lower rate of weight loss than you might expect. In some cases, it could even lead to weight re-gain.

To add insult to injury, a rise in cortisol from the stress of dieting can cause our bodies to hold onto more water, making us feel “softer” and “less lean” than we actually are.

Interestingly, this is just one example of the amazing and robust response to trying to manipulate one variable (in this case, actual calories eaten). There are similar responses when trying to manipulate each of the other variables in the equation.

For example, research suggests that increasing physical activity above a certain threshold (by exercising more) can trigger:

  • Increased appetite and more actual calories eaten
  • Decreased calories not absorbed as we absorb more of what we eat
  • Decreased RMR
  • Decreased NEAT

In this case, here’s what the equation would look like:
In the end, these are just two of the many examples we could share. The point is that metabolism is much more complicated (and interdependent) than most people realize.

Therefore, trying “what used to work” for you, or relying on calorie counting, often won’t get you the results you want. As your energy balance evolves, so must your strategies for losing fat or maintaining your weight.

Understanding energy balance means setting better expectations about body change.

It’s important to note that if you have lots of body fat to lose, many of these adaptations (i.e. lowered RMR, PA, NEAT, etc) don’t happen right away. But, as you become leaner, this “adaptive thermogenesis” kicks in.

It’s also important to know that how your metabolism reacts to changes in energy balance will be unique to you.

How much you can lose or gain will depend on your age, your genetic makeup, your biological sex, if you’ve had relatively more or less body fat and for how long, what medications you’re taking, the makeup of your microbiome… and probably a whole lot of factors we don’t even know about yet.

But let’s try to simulate how this could work.

Scientists at the National Institutes of Health have studied the data from people who have lost weight, and created a mathematical model that represents how weight and fat loss actually happens in the real world.

We can play with it, using the Precision Nutrition Weight Loss Calculator.

Let’s start with a 40-year-old male, with a starting weight of 235 lbs and a height of 5’10”. We’ll call him Frank.

Frank works a desk job, and is only lightly active outside of work. This calculates that he needs 2,976 calories of energy per day to maintain his current weight.

By knocking off 500 calories per day, his intake drops to 2,476 calories daily. And he doesn’t plan on changing his physical activity.

Now, you’ve probably heard somewhere that a pound is equivalent to 3,500 calories, which means that if we take away those 500 calories from Frank every day, he should lose 1 pound per week (500 x 7 days = 3500 calories).

He should end up at 183 lbs after one year of consistently eating 500 fewer calories every day. (According to this math, then, he would weigh 0 lbs within 5 years, which should raise some red flags.)

But we know it doesn’t exactly work this way in real life.

At the end of a year, Frank gets on the scale. He’s 205 lbs.

What the hell?

That’s 22 pounds more than I should be!

Frank rages to his wife Maria, who smiles knowingly. She’s 40 too, and has been trying to lose weight since having two kids in her mid-30s.

Tell me about it, she says. I’ve lost and gained the same 10 pounds over and over, even though I’ve been exercising and eating pretty healthy.

Then they both think:

Maybe I should try that juice cleanse after all. My body is obviously broken.

Nope, nobody is broken. Don’t hit that juice cleanse just yet.

Instead, Frank and Maria could both benefit from a clear understanding of how weight loss actually works. Then they can set appropriate behavior goals, and have realistic expectations for their progress.

(Postscript: Frank and Maria decide against the juice fast and enroll in Precision Nutrition Coaching. At the end of a year, Maria’s “only” lost a total of 7 lbs, but has gained 5 lbs of muscle . Her firm arms and glowing skin are the envy of the other moms. Frank is down to a fit 185 lbs and trying to figure out how to convince Maria that he should buy a mountain bike.)

So, does dieting damage the metabolism?

Despite what you may have heard:

No, losing weight doesn’t “damage” your metabolism.

But because of the adaptations your body undergoes in response to fat loss (to prevent that fat loss, in fact), ‘energy out’ for those who have lost significant weight will always be lower than for people who were always lean.

Rather:

Losing weight, and keeping it off, is accompanied by adaptive metabolic, neuroendocrine, autonomic, and other changes.

These changes mean that we expend less energy — around 5-10 percent less (or up to 15 percent less at extreme levels) than what would be predicted based on just weighing less.

Unfortunately, because of this adaptive response, someone who has dieted down will often require 5-15 percent fewer calories per day to maintain the weight and physical activity level than someone who has always been that weight.

(Or even less, potentially, because as we learned in the very beginning, the RMR of people of the exact same age/weight/etc. can still vary by up to another 15 percent.)

This means someone who was never overweight might need 2,500 calories to maintain their weight, while someone who had to diet down to that weight may need only 2,125-2,375 calories to hold steady.

We don’t know how long this lowered energy expenditure lasts. Studies have shown that it can hang around for up to 7 years after weight loss (or more; 7 years is as far as it’s been studied). This likely means it’s permanent, or at least persistent.

This is extra relevant for people who have repeatedly dieted, or for fitness competitors who may repeatedly fluctuate between being extremely lean and being overweight in the off-season.

I don’t have data to back this up (to my knowledge no one has studied it), but adaptive thermogenesis seems to react more strongly or more rapidly with each successive yo-yo of extreme body fat fluctuations.

All of this explains why some people can feel like they’ve “damaged” their metabolism through repeated dieting. (And why some experts suggest “metabolic damage” is a real thing.)

But nothing really has been “damaged”.

Instead, their bodies have just become predictably more sensitive to various hormones and neurotransmitters. Their metabolic rates are understandably lower than predicted by various laboratory equations.

So, where does this leave us?

Even folks whose bodies resist fat loss or muscle gain can accomplish these goals.

All physiological changes — including weight loss or gain, fat loss or gain, and muscle loss or gain — require different efforts and amounts of time for different people.

But even if your body does resist weight loss, you can still lose fat, gain muscle, and dramatically change your body.

Our Precision Nutrition Coaching men’s and women’s Finalist Halls of Fame are clear evidence of that.

What to do next:
Some tips from Precision Nutrition.

The physiology of weight loss is complicated, but the best strategies for losing fat and keeping it off don’t have to be.

1. Eat plenty of protein.

Protein is essential when trying to losing weight / fat for a few reasons.

  • Protein helps you keep that all-important lean body mass (which includes connective tissues, organs, and bone as well as muscle).
  • Protein significantly increases satiety, which means you feel fuller despite eating less. (And eating more protein often causes people to eat less overall.)
  • Just by eating more protein you burn more calories, because of the increased thermic effect of eating.

For example, if you’re eating 2,500 calories daily, 15 percent from protein, 50 percent from carbs, and 35 percent from fats (roughly average for US adults), you’re burning approximately 185 calories per day through digestion.

Maintain your total calorie intake but increase protein to 30 percent, drop carbs to 40 percent, and whittle fat to 30 percent, and your TEE goes up to roughly 265 calories per day.

  • For most active men: 6-8 palm-sized servings of protein per day.
  • For most active women: 4-6 palm-sized servings per day.

For a complete guide to using your hand to measure portions, check out our Calorie Control Guide infographic.

2. Eat a wide variety of fruits, vegetables, quality carbs, and healthy fats.

Vegetables are loaded with vitamins, minerals, phytonutrients, water, and fiber to help you fill up during meals, stay full between meals, keep you healthy, and recover from your workouts.

  • We recommend 6-8 fist-sized servings per day for most active men.
  • And 4-6 fist-sized servings per day for most active women.

The carbs will fuel training, boost leptin (a super important hormone), keep up sex hormones, and prevent feelings of deprivation.

And the fats also keep up sex hormones, boost the immune system, suppress excess inflammation, and make food taste really good.

  • For most active men, this would be 6-8 handfuls of quality carbs, and 6-8 thumbs of healthy fats per day.
  • For most active women, 4-6 handfuls of quality carbs and 4-6 thumbs of healthy fats per day.

For a complete guide to using your hand to measure portions, check out our Calorie Control Guide infographic.

3. Adjust your intake as you plateau, or to prevent plateaus.

As your weight loss progresses, you will need to lower your calorie intake further to continue to progress, as your smaller body will burn fewer calories, and your body is adapting to your diet.

Be ready, willing, and able to adjust portion amounts by removing 1-2 handfuls of carbs and/or 1-2 thumbs of fats from your daily intake. Then reassess and continue to adjust as needed.

However, one study found that weight loss plateaus have less to do with metabolic adaptations and more to do with “an intermittent lack of diet adherence”. In other words, not actually sticking to a nutrition plan consistently.

Research shows that we usually think we’re eating less and exercising more than we truly are. So do an objective review of your actual energy in and out before assuming your body is blocking your efforts.

4. Understand that this is complex.

So many things influence what, why, and when we choose to eat.

Too often, eating and body size / fatness are blamed on lack of knowledge, lack of willpower/discipline, or laziness. In reality, food intake and body composition are governed by a mix of physiological, biological, psychological, social, economical, and lifestyle influences, along with individual knowledge or beliefs.

One of the simplest ways to make your decision processes easier is to create an environment that encourages good food choices and discourages poor ones. This can mean making changes to your daily routine, who you spend time with, where you spend time, and what food is readily available to you.

But remember that weight loss can and should be relatively slow, so aim to lose about 0.5-1 percent of your body weight per week.

This helps to maintain muscle mass and minimize the adaptive metabolic responses to a lower calorie intake and resulting weight loss. Faster weight loss tends to result in more muscle loss without extra fat loss, as well as a larger adaptive response.

5. Cycle calories and carbs.*

For folks who are trying to get quite lean, at some point you can’t just rely on linear dieting to get you there. By strategically cycling calories and carbs, you can help to limit how much the metabolism-regulating hormone leptin drops (or temporarily boost it back up) – attenuating the adaptive and hunger response.

*Note: This is a higher-level strategy for fitness competitors and elite athletes who need to get very lean (i.e. ~6-9 percent body fat for men, and ~16-19 percent for women). It’s not something for the average person.

6. Refeed periodically.**

When getting to extreme levels of leanness, even strategic calorie and carb cycling might not be enough. So take out the big guns, and employ some periodic re-feeds to temporarily boost leptin and insulin and keep fat loss going.

**Note: This is a higher-level strategy for fitness competitors and elite athletes who need to get very lean (i.e. <6 percent body fat for men, and <16 percent for women).

7. Do a mixture of resistance, cardiovascular, and recovery activity.

Resistance training helps you maintain vital muscle mass, burn calories, and improve glucose tolerance. Cardiovascular exercise improves the health of your cardiovascular system, helps you expend energy, and can improve recovery.

But don’t overdo either one.

Recovery work (e.g. foam rolling, walking, yoga) helps you maintain consistency and intensity with resistance and cardio training, making them more effective. And it helps to decrease stress (lowering cortisol), which also helps you lose body fat and keep it off.

Aim for 3-5 hours per week of purposeful activity.

8. Find ways to increase NEAT.

Even small increases in activity can account for hundreds of daily calories, and therefore make a big difference in fat loss efforts.

Some ideas: Get a stand-up desk or a treadmill desk; fidget; pace while on the phone; take the stairs; park your car farther away from where you’re going.

9. Develop a solid nightly sleep routine and manage your stress.

Sleep is just as important to your success as nutrition and activity levels. Don’t pretend that you can get by with less. It simply isn’t true.

Often, when people lower their stress, they lose a lot of body water. Then they also notice that they may have lost fat too. (Plus, they may discover that chronic inflammation goes down — another win.)

This includes mental and emotional stress. Research on cognitive dietary restraint (i.e. worrying and stressing out about food) shows that constantly and negatively fixating on what you eat (or don’t) can have the same unhealthy effect as actually dieting stringently.

Yet we need some stress to actually help with progress and growth, so find your stress sweet spot.

10. Have some self-compassion.

There are going to be meals or days where you don’t eat as you “should”. It’s OK. It happens to everyone. Recognize it, accept it, forgive yourself, and then get back on track.

Research actually shows that self-compassion and flexible eating is associated with lower BMI and a healthier body weight, lower self-reported calorie intake, less anxiety and stress, and a better relationship with food.

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what will happen to you if you eat below ur BMR?

Your BMR is based on your current weight–it is what it would take to maintain your current weight if you did nothing but lay in bed all day. So, if you are significantly overweight and basically sedentary, it’s true you could safely eat a little less than your starting BMR, as your body will be able to make up for the shortage by taking energy from your stored fat.
But you can cause yourself both health and weight loss problems by dropping your calorie intake too low and/or too quickly. Going below 1200 cals/day makes it very hard for anyone to get everything you need for good basic nutrition. And even though you can survive while eating less than your BMR, having more than a 1000 calorie/day (500 for someone who is not so overweight) difference between calories in and calories out is clearly associated with lots of problems, including the tendency to lose more muscle and organ tissue during weight loss, and the likelihood of putting the fat back on later on.
Your body will have a much easier time with shedding extra fat when you keep it operating at a high enough level to engage in exercise and activity without cannabalizing excessive amounts of muscle and organ tissue for energy. That means eating at least enough to cover what your BMR would be at a healthy weight, plus your current level of activity and exercise, and the energy it takes to digest your food. The recommended calorie range you get from SP is designed to allow for this.
If you are significantly overweight, and want to calculate things for yourself, it’s often a good idea to use your healthy goal weight rather than your current weight to establish your minimum safe calorie intake (or the minimum necessary to maintain good nutrition–1200 cals/day–which ever is HIGHER). If you are very overweight, like I was, it may be better to use a weight that is halfway between your current weight and your goal weight. This will help you avoid sending your body into “diet shock” by lowering your calorie intake too quickly.
Keep in mind that your body is designed to maintain all kinds of things (including emergy balance) within a certain narrow range of acceptable limits. Whenever you do something that upsets the applecart, your body will react by going overboard in the opposite direction, trying to restore the former balance. If you suddenly start going too low on calories to maintain the status quo, it will slow down your metabolism so that you burn much fewer calories doing what you normally do–this is how it tries to maintain energy balance. Burning up muscle instead of fat for energy is how it slows your metabolism–it wants to get rid of the muscle because muscle uses up much more energy than fat, which you can’t afford when there aren’t enough calories to go around. Your brain will also start pumping out chemicals that will increase your appetite and make you start obsessing about food and eating, all to get you to increase your calorie intake again.
The only way around this problem of shifting into “muscle-eating, fat-saving, obsessing about food mode” (otherwise known as starvation mode) is a moderate approach to weight loss that combines a reasonable calorie reduction with extra calorie expenditure through exercise. This gives your body a chance to adapt and adjust the way you want it to–by using your extra fat to make up for the calories you aren’t eating, instead of freaking out and resorting to a bunch of unhealthy tricks designed to keep you from starving to death.
Hope this helps.
Coach Dean
Edited by: SP_COACH_DEAN at: 5/13/2006 (12:01)

What Is BMR and TDEE + How to Use Them to Lose Weight

Sometimes half the battle of weight loss is just knowing what and how to track certain metrics.

If you can’t measure it, you can’t manage it.

And that goes for most aspects of our lives, right?

For many people, weight loss success is dependent on having an effective system of tracking calories.

Calories in, calories out (CICO), right?

Weight loss really is that simple, but how can you figure out how many calories you burn per day? In other words, how do you figure out your baseline and determine how many calories you should be eating?

That’s where understanding BMR (Basal Metabolic Rate) & TDEE (Total Daily Energy Expenditure) comes in. These formulas calculate how much energy you spend per day, and this allows you to set your calorie goals much more efficiently.

So when you understand your BMR and TDEE and the relationship between them, it gets a lot easier to reach your weight loss goals.

Let’s start with a bit more detail on what they are, and then we’ll discuss using them in your day-to-day weight loss routine.

What is BMR?

Basal Metabolic Rate (BMR) is how many calories you burn when your body is resting.

In other words, it’s the calories your body needs to keep you alive. This is the bare minimum. Imagine you were in a coma — that’s the base level we’re talking about here.

You think of these as your “rainy day” or “couch-potato” calories. 🙂

No physical activity needed!

People use BMR and other metrics to figure out how many calories they burn per day regardless of what they do. By knowing this number, you can factor in your workouts or activity and figure out how many calories you need per day to meet your weight loss goals.

Basal means “forming or belonging to a bottom layer or base”. It’s the fundamentals.

But, that doesn’t there isn’t a lot happening beneath the surface. In fact, between 60-75% of your daily calories are burned during these processes. Think about everything going on while you lie in bed: your heart has to pump blood, your lungs need to pull in and push out oxygen, and then that oxygen needs to be delivered to your brain and the rest of your body.

The energy required to perform fundamental processes like ventilation, blood circulation, and temperature regulation is dependent on your weight, height, age, and gender.

BMR is also used interchangeably with BEE (Basal Energy Expenditure) and is similar but not equal to RMR (resting metabolic rate) or REE (resting energy expenditure).

BMR is a slightly more restrictive definition than RMR, but many people confuse their definitions. True BMR calculation requires patients to spend the night in a test facility the night before official testing. If you’d like to be that exact, you’ll need an appointment.

Scheduling an appointment isn’t necessary, though!

For our purposes, we will be looking at the practical methods for calculating BMR, which essentially becomes RMR when calculated with a formula instead of testing.

So to clarify, getting an exact BMR is quite difficult, but using a formula to get an estimation is more than enough to get your weight loss goals underway.

Calculating Your BMR

People debate how best to calculate BMR, but the formulas all consist of some essential elements:

  • Gender
  • Age
  • Weight
  • Height
  • Activity
  • Body Fat (optional)

The quickest way to calculate your BMR is to use an online calculator, which you can find here.

Or if you’d rather do the math yourself, you can use these gender-specific equations known as the Harris-Benedict Formula.
This Harris-Benedict Formula summary is via EverydayHealth.com.

Male BMR Formula

BMR Formula:

66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)

Example:

So if you’re 170 pounds, 5’11”, and 43, your BMR is 66 + (6.23 x 170) + (12.7 x 71) – (6.8 x 43) = 1,734.4 calories.

What is TDEE?

Total Daily Energy Expenditure (TDEE) is an estimation of how many calories you burn each day including typical exercise.

TDEE is just BMR with estimations added in. It’s the same formula except you add in a multiplier that’s dependent on how much “activity” you have in a given day.

So for example, if you exercise 3-5 days per week, you’d multiply your BMR by 1.55.

You think of TDEE as adding in everything you do in a normal day to your BMR calculation.

This includes all the working out we do as well as all the little things we do like showering, walking around the office, taking out the trash, cuddling with puppies, yelling at the TV… You know. Normal stuff.

By adding the number of calories needed to do these things with your BMR you get your TDEE.

If your calorie consumption is equal to your TDEE, you will maintain your current weight.

If your calorie consumption is less than your TDEE then you will lose weight.

It’s really that simple.

Calculating Your TDEE

Based on the amount you exercise, use the following multiples:

  • If you rarely exercise, multiply your BMR by 1.2
  • If you exercise on 1 to 3 days per week, multiply your BMR by 1.375
  • If you exercise on 3 to 5 days per week, multiply your BMR by 1.55
  • If you exercise 6 to 7 days per week, multiply your BMR by 1.725
  • If you exercise every day and have a physical job or if you often exercise twice a day, multiply your BMR by 1.9

So following the EverydayHealth examples, if the man exercises 3 days a week, his daily caloric requirement is 1,734.4 x 1.55, or 2,688.3 calories.

And if the woman in the example exercises 6 days a week, her daily caloric requirement is 1,357.4 x 1.725 or 2,342.5 calories.

Using BMR & TDEE to Lose Weight

Once you know your BMR and TDEE, all you need to do is make sure your caloric intake is less than that number!

So if your TDEE ends up being 2,200 calories per day, you need to eat fewer calories to achieve “weight loss”.

How fast you lose it depends on how much your deficit is every day.

Generally speaking, there are about 3,500 calories in a pound.

Most dieticians recommend eating a deficit of anywhere between 500-1,000 calories a day.

The goal is not to lose weight the fastest — it’s to be consistent.

Think turtle over rabbit when losing weight.

So looking at a TDEE of 2,200, if you aimed for 1,700 calories per day, you’d be eating at a 500 calorie deficient. This would put you at approximately losing 1 pound per week.

And to test the accuracy of your TDEE, just see if your weight drops by about a pound per week. If not, you may be over or underestimating your BMR or TDEE multiplier.

Pretty cool, right?

Weight Loss in Practice

Then, all you need to do is track your calorie intake via an app like MyFitnessPal and adjust your TDEE multiplier as your exercise routine changes.

I’d also grab a cheap kitchen scale if you don’t have one already — being able to measure out your foods saves a lot of guessing and headaches when calorie counting. You can grab one for $10 or so on Amazon, and they also help a lot when meal prepping.

Meal prepping is going to be your best bet for staying on top of a calorie deficit! You can make one big meal, split it by calories and weight into separate containers, and just grab and go.

The more barriers you can reduce when having to think about your calories, the better you will do, I promise.

Here are some great meal prep recipes for you to dig into.

Conclusion

There you have it!

Again, the relationship between BMR and weight loss and TDEE is key to accurately setting your weight loss goals.

Just knowing what your body needs and how your unique BMR & TDEE affect your weight loss strategy will help you immensely when trying to lose weight.

Without your metrics, you’re just guessing.

Start by calculating your BMR — reduce as many variables as you can, and then figure out your TDEE.

to that online calculator again.

Once you have your numbers, pick a calorie deficit that you feel confident sticking to, and start your journey toward the life of your dreams.

Wishing you all the luck!

What I learned about weight loss from spending a day inside a metabolic chamber

When scientists offer mice or rats a spread of junk food, they consistently find that only some overeat and puff out into little rodent blimps, while others maintain a normal body size.

A similar thing happens in people. In the US, and around the world, we are now overwhelmed with highly palatable, cheap calories. This has helped obesity rates soar on average. But not everyone overeats and becomes overweight, and not everyone who becomes overweight or obese develops illnesses like diabetes or heart disease. This individual variation — why we have different responses to extra calories and weight — is one of the greatest mysteries of modern medicine.

The best place to find answers is an 11-by-11.5-foot room in suburban Washington, DC. This summer, I spent a day there, one of fewer than 100 patients who will do so this year.

The National Institutes of Health Clinical Center’s airtight “metabolic chamber” is furnished only with an exercise bike, a toilet, and a bed. For 23 hours in June, I was sealed in the chamber, while nurses monitored me constantly through a plexiglass window and video camera in the ceiling.

Like a prisoner in solitary confinement, I ate meals delivered through a small, air-locked opening in the wall. Since researchers were measuring every calorie I used, any leftover scrap had to be sent back through the wall and recorded. A heart monitor and three accelerometers on my wrist, waist, and ankle tracked my every heartbeat and movement.

Inside the metabolic chamber at the National Institutes of Health Clinical Center in Bethesda, Maryland. The chamber has a “clean” airlock portal where subjects receive their meals, and a “dirty” one where they can pass back any leftovers. Christina Animashaun/Vox

There are only about 30 metabolic chambers in the world, and the NIH is home to three. These highly sensitive, multimillion-dollar scientific instruments are considered the gold standard for measuring metabolism. They’ve furthered our understanding of obesity, metabolic syndrome, and diabetes — diseases that are now among the greatest threats to health worldwide — by letting researchers carefully track how individual bodies respond to the calories they’re offered.

My participation, as a normal weight “control” subject in an obesity phenotyping study, would be used toward this lofty goal.

But I wasn’t interested in joining the study just for the sake of science; I had selfish motivations too. As kids, my two brothers and many of my friends seemed to be able to binge on junk food without gaining weight. Today, my husband can gulp down mountains of pasta and remain skinny. I, on the other hand, have always noticed the scale creeps up quickly when I’m not careful about my diet. And I’ve harbored a suspicion that a “slow metabolism” might help explain my lifelong struggle to control my weight.

Being a self-imposed NIH prisoner was an exciting and rare opportunity — to see one of the most important scientific tools in obesity research up close and to finally get some answers on this long-simmering question about my body.

But my day in the chamber revealed the depths of my misunderstanding about my metabolism. And that the obsession with metabolism speed is distracting, destructive, and based on a myth about obesity and weight management.

Metabolism, explained

If you’ve surveyed the covers of women’s magazines, watched Dr. Oz’s TV show, or strolled down the supplement aisle at the grocery store, you might think your metabolism is a single thing that can be calibrated with “metabolism boosters” like chili peppers or coffee, or by following special diets.

In reality, metabolism is the thousands of chemical reactions that turn the energy we eat and drink into fuel in every cell of the body. These reactions change in response to our environments and behaviors, and in ways we have little control over. (Eating certain foods and exercising a little more generally shifts our metabolic rate only marginally.)

Julia Belluz/Vox

There are three main ways the body uses calories. There’s the energy needed to keep our hearts, brains, and every cell of our body working, known as the basal metabolism. There’s the energy used to break down food, known as the thermic effect of food. And there’s the energy burned off during physical activity — like walking around, fidgeting, or exercising.

The basal metabolic rate accounts for the largest amount of the total calories a person burns each day (65 to 80 percent for most adults). Physical activity, on the other hand, accounts for a much smaller portion — 10 to 30 percent for most people — despite what many people believe. And digesting food accounts for about 10 percent.

There are several predictors of how fast or slow a person’s metabolic rate will be. These include the amount of lean muscle and fat tissue in the body, age, and genetics. Women tend to burn fewer calories than men. Having a higher metabolic rate means your body uses food for fuel (instead of storing it as fat) more quickly. But you can still gain weight if you consume more calories than your body needs. Counterintuitively, heavier people generally have higher metabolic rates than skinny folks to meet the fuel demands of their larger bodies.

These processes, essential to any living organism, are complex, and scientists had been working to unravel them for centuries before the obesity crisis hit.

An engraving of Santorio Sanctorius, a 17th-century doctor and scientist, sitting in his “static weighing chair.” SSPL/Getty Images

In the early 1600s, Santorio Sanctorius, an Italian doctor and “founding father of metabolic balance studies,” ran one of the first controlled experiments of human metabolism. He invented the “static weighing chair,” a device that allowed him to weigh himself before and after meals, sleep, toilet breaks, even sex. He noticed fluctuations in his bodyweight, and concluded these could be explained by “insensible perspiration.”

One hundred years after that, French chemist Antoine Lavoisier used a device called an “ice calorimeter” to gauge the energy burn from animals —like guinea pigs — in cages by watching how quickly ice or snow around the cages melted. This research suggested that the heat and gases respired by animals, including humans, related to the energy they burn.

The “metabolic chamber” I entered evolved from Sanctorius and Lavoisier’s work. Over the years, researchers probing the mysteries of the metabolism figured out that the amount of oxygen we take in, and carbon dioxide we let off, changes depending on how quickly we’re using calories and the type of calories we’re using. Measuring these gases in airtight environments can determine a person’s metabolic rate.

The debunking machine

The metabolic chamber — also known as a whole-room calorimeter — is the most precise tool available to track this gas exchange minute by minute.

NIH’s three chambers opened in 2007 to focus on the growing obesity epidemic. Eighteen researchers now use the rooms to run about 400 studies every year. And they are part of a broader “metabolic unit” dedicated to understanding the weight problems, obesity, and diabetes that currently affect up to a third of the people on earth.

A hallway leading to the chamber. Through an array of metal pipes spread on the chamber’s ceiling, researchers capture and measure oxygen consumption and CO2 production. Christina Animashaun/Vox

Studying thousands of subjects in the metabolic unit — the chambers plus NIH hospital wings for patients with diabetes and obesity — has helped researchers show how adaptable the metabolism is, and how it works with our appetite, body composition, and physical activity levels to adjust the calories we’re burning at any moment.

For example, by giving people a medication that causes them to lose (through their urine) an extra 360 calories per day, they’ve shown that we unknowingly compensate for those calories lost by eating more.

They’ve found that exposing people to cold temperatures while they sleep causes them to accumulate more brown fat — fat tissue whose main function is heat production — and burn more calories. (These results reversed completely when the study participants slept in warmer temperatures again, revealing how dynamic metabolism is.)

In a remarkable study of Biggest Loser reality TV show participants with obesity, researchers showed that crash dieting can permanently slow a person’s metabolic rate, leading them to hang on to the calories they were eating for longer, though this isn’t true for everybody who loses weight.

The big theme in many of these studies: Our metabolism silently shifts under new conditions and environments in ways we’re not usually aware of.

When it comes to diets, the researchers have also debunked the notion that bodies burn more body fat while on a high-fat and low-carb ketogenic diet, compared to a higher-carb diet, despite all the hype.

“We could have found out that if we cut carbs, we’d lose way more fat because energy expenditure would go up and fat oxidation would go up,” said Kevin Hall, an obesity researcher at NIH and an author on many of these studies. “But the body is really good at adapting to the fuels coming in.” Another related takeaway: There appears to be no silver bullet diet for fat loss, at least not yet.

Many basic metabolism mysteries remain. It’s not fully known why two people with the same size and body composition have different metabolic rates. They also don’t know why people can have different metabolic responses to weight gain (where some people with obesity develop insulin resistance and diabetes, for example, and others don’t). They don’t know why certain ethnic groups — African Americans, South Asians — have a higher risk of developing metabolic disorders like diabetes, and why people with diabetes have a higher cardiovascular disease risk.

They haven’t even figured out how the brain knows what the body weighs and, therefore, the mechanism that controls our metabolic rate.

“If I knew how the brain is aware of how much the body weighs, and how to regulate how many calories it burned off, I could change that setting and help an overweight person burn more calories through an increase in metabolic rate,” NIH metabolism and brown fat researcher Aaron Cypess told me over the phone before my stay.

Cypess is using the chambers to work toward that, and figure out whether there might be a drug that can do what very cold temperatures do: help people burn more calories. These and other studies in the chamber are a gold mine for data on the metabolism’s mysteries — data that could eventually help uncover cures for obesity and diabetes.

The meaning of metabolism

For my part in the research, I’d undergo a battery of physical tests — from blood draws to an EKG — and spend a day and night in the chamber. In addition to watching how much I moved and what I ate, the scientists would get a reading on precisely how many calories I burned and what type (carbohydrates, fat, or protein), every minute of the 23 hours I called the chamber home. I’d also have my metabolic rate checked using two other methods (the “metabolic cart” and “doubly labeled water”; more on these later).

In return, I’d get more granular data about how my body works than I ever could’ve hoped for. And that made me anxious.

Christina Animashaun/Vox

At age 34 and 5-foot-9, my weight hovers in the 150s, and my BMI is normal. But even as a child, I was chubby and seemed to enjoy sugary and fatty foods more than other members of my family. During my late teens and 20s, I struggled to manage my weight and was at times overweight — a situation that worsened at the end of high school. I moved to Italy and indulged in all the pizza, ice cream, carpaccio, and mozzarella my little town in Abruzzo had to offer. Like a research mouse, I puffed out and returned to Canada the following year depressed about my body. It took several years to really start the process of slimming down.

I’d long believed these fat years somehow wreaked havoc on my body. Specifically, I thought they slowed down my metabolic rate, and that that made me prone to weight gain. But I was about to learn this idea I’d held on to for so long was wrong.

How the metabolic chamber actually measures metabolism

Halfway through my morning in the metabolic chamber, I had eaten and rested at prescribed intervals, and hit the exercise bike for 30 minutes. I also meticulously recorded all my activities in a log — when I was standing and reading, lying down, on the bike — so that the researchers could compare how they tracked against my calorie burn.

Just before lunch arrived, Kong Chen, a metabolism investigator at NIH’s National Institute of Diabetes and Digestive and Kidney Diseases, turned up on the other side of my plexiglass window to say hello.

“How are you doing in there?” he asked.

I was surprisingly comfortable in the little room, I told him, and asked if he could walk me through precisely how the chamber does the work of measuring the metabolism.

Chen, who has a PhD in biomedical engineering, explained that the room I was standing in was almost airtight, with a fixed volume of oxygen and CO2. Through an array of metal pipes spread across the ceiling, researchers captured and measured the oxygen I consumed and the CO2 I produced at every minute.

The reason these gasses matter for metabolism is simple, Chen said. We get fuel in the form of calories — from carbohydrates, fat, and protein. But to unlock those calories, the body needs oxygen. When we breathe in, oxygen interacts with the food we’ve consumed, breaking down (or oxidizing) chemical bonds where the calories are stored and releasing them for use by our cells. The product of the process is CO2.

When air is sucked out of the chamber through the pipes, two things happen: First, gas analyzers measure everything the person inside respired, Chen said. Then the gas analyzers send the values for oxygen consumption and CO2 production to a computer, where researchers like Chen plug them into equations to calculate calories burned and what type of fuel was oxidized.

The amount of CO2 we’re releasing, and the proportions of CO2 to O2, changes depending on how many calories we’re using and whether those calories came from carbs, fat, or protein.

The reason these minute-to-minute measurements are so important is that they allow the chamber to detect subtle shifts of energy expenditure — as little as a 1.5 to 2 percent change over 24 hours — in a way no other tool can. “If you have an intervention — a drug or diet — that changes a person’s physiology by a small percentage, we can measure that,” Chen said proudly.

Kong Chen, a metabolism investigator at NIH’s National Institute of Diabetes and Digestive and Kidney Diseases, speaking to me before my “metabolic cart” test, in a hospital room outside of the chamber. Christina Animashaun/Vox

The next best metabolism measuring method, called doubly labeled water, involves drinking a sample of water that contains (or is “labeled with”) forms of the elements deuterium and oxygen-18. Since they’re not normally found in the body, researchers can determine a person’s metabolic rate by tracking how quickly they’re expelled through urine sampling. But doubly labeled water can only detect a 5 percent change in metabolic rate over seven to 10 days, which is less than half as precise as the metabolic chamber.

These tiny changes in calorie burn might sound insignificant, but over time, they add up. “Ultimately,” Chen said, “it only takes maybe a 100 calorie-per-day difference between food intake and energy expenditure over a few years to gain 10 pounds.” So an extra cookie a day can mean the difference between fitting in your jeans or not.

I asked Chen whether he’d ever used the chamber himself. He told me he was his own first subject, part of an early validation study. What did he learn, and did it change his behavior?

“I found myself to be fairly normal in terms of metabolic rate, which is good and bad I suppose,” he said. “Good because I’m metabolically normal. But it also means that I’m probably just as at risk to anyone else to gaining weight if I’m not watching it. So I’m not one of those people that can eat all they want and not gain weight.”

After Chen’s visit, the rest of my day in isolation whirred by with several more rest periods, exercise bursts, and meals. I went to bed that night thinking about Chen’s results and wondering what the chamber would reveal about me.

“You’re perfectly normal”

The next morning, I woke up groggy from six hours of light sleep. I was eager to open the heavy steel door and get into fresh air.

But the experiment wasn’t over. A “metabolic cart” — which looked like a computer on rollers connected to a tube and a plastic hood — arrived to measure my resting energy expenditure, or metabolic rate when I’m awake but not physically active, and before eating anything. So I lay in a hospital bed as a technician fitted the clear domed hood over my head while the machine captured the CO2 I respired.

A technician measures my resting energy expenditure with a “metabolic cart” right after I wake up. Christina Animashaun/Vox

On my way out of the hospital, I said goodbye to Chen and thanked the nurses who had cared for me. They reminded me to collect urine samples every day for a week so they’d get a final measure of my metabolism, using the doubly labeled water method. I’d also continue wearing the three accelerometers. Together, this data would give the researchers a sense of my average daily calorie burn as a “free-living subject,” outside the hospital.

A few weeks later, I called Kevin Hall to go over my results. What most surprised me: There was a pretty wide gap between how healthy I was and how unhealthy I expected I’d be.

“ suggest you’re perfectly normal,” Hall said.

My metabolic rate was what he’d have predicted for someone my age, height, sex, and weight. In other words, I didn’t have a “slow metabolism.” I had burned the equivalent of 2,330 calories per day in the chamber, including during sleep, and most of those calories (more than 1,400) were from my resting energy expenditure. My biomarkers — my heart rate, cholesterol levels, blood pressure — were all excellent, suggesting no heightened disease risk leftover from my overweight years.

There were other revealing takeaways. Staying awake cost my body only a few more calories than sleeping, which didn’t surprise Hall. “We know the sleeping metabolic rate is about 5 percent less than resting metabolic rate when you’re awake,” he explained.

What’s more, the 405 calories I burned during 90 minutes on the exercise bike was both less than is advertised in spinning classes and just 17 percent of the total calories I had used, validating once again that workouts typically account for a relatively minor part of total energy expenditure.

Even during sleep, my body was busy. “This goes into the question of, ‘Does your brain’s energy expenditure go up when you’re doing a hard math problem compared to when you’re zoning out watching TV?’ And everyone who has measured that has said ‘no’ — it’s a fixed amount, and your brain is not inactive at any point in time,” Hall said.

Christina Animashaun/Vox

As for the “calories in” part: I consumed about 1,850 calories (including 18 percent protein, 36 percent fat, and 46 percent carbs) of the 2,250 calories provided to me. That means I was in an energy deficit, and if I continued eating that much, I’d lose weight.

I also found out that I’m bad at estimating my calorie consumption. During my chamber stay, I told a nutritionist what I’d eaten the day before and filled in a survey of my food consumption over the past year. Based on that, she’d calculated I was eating only 1,500 to 2,000 calories per day. I thought I was being incredibly thorough and generous in my accounting, but if this was really all I ate, I’d be thinner than I am.

The results of these food surveys made me wonder how many of us blame some aspect of our biology for weight gain when we’re really just underestimating our calorie intake, forgetting all the little extras we eat and drink that can add up to pounds over the years. It seems I had too.

I asked Hall if there were any other potential explanations for why I felt I gained weight so easily. He told me NIH does other studies that could answer that. If he had tracked my metabolism before I had lost weight earlier in life, he’d be able to detect any slowdown in response to slimming. Or if I participated in an “overfeeding study” — where I was deliberately fed more calories than my body required — he might detect no change in my metabolic rate. There are some people whose metabolic rate speeds up when they overeat, using the extra calories as fuel instead of storing them as fat, and it’s possible I’m not one of them.

But we didn’t have that data, and according to what he could see, I was in perfect health.

The metabolism myth

I hung up the phone and reflected on the chamber experience — and my quest to better understand my body.

Spending time at NIH reminded me that our epidemic of weight problems, in addition to damaging our physical health, has left in its wake an epidemic of psychological scars — even in those who, like me, manage to lose weight.

I was genuinely surprised, and somewhat relieved, when nurses and doctors kept referring to my biomarkers as “excellent” and to me as “very fit.” Even though I know my bodyweight is in a healthy range, I still feel like a chubby kid.

And you don’t need a history of weight problems to experience these feelings of inadequacy. Celebrities and big businesses — like Goop and Dr. Oz and many of the supplement, wellness, and exercise companies out there — have minted billions off stoking our anxieties about our physical shortcomings. If we only tried a new exercise, bought a new gizmo, or ate a certain way, they suggest, we’d be slimmer, glowier, healthier.

Yet the truth of the metabolic chamber is that there’s a lot of variation in how people respond to diets and exercises, and so far, no single approach has worked to help everybody. That’s why so much of the one-size-fits-all weight loss advice we’re steeped in is so frustrating and futile for so many.

The chamber has also shown that while some people have a “slow metabolism” relative to others their size and age, this isn’t a major cause of obesity. And despite the focus on “metabolism boosting” for weight loss, there’s nothing money can buy that will speed your metabolism up in way that will lead to substantial slimming.

When I look back at what helped me lose weight, there was never a magic bullet — a special diet, exercise regimen, or supplement — that worked. Through plodding trial and error, I discovered habits and routines I could stick with to help me eat less and move more.

I don’t keep junk food in the house, I avoid eating out a lot, I prioritize sleep, and I try to fill my plates with fruits and vegetables. As for exercise, I build it into my daily life — walking or biking to work, or during lunch breaks. And I’ve found mornings and weekends best for dedicated workouts (yoga, running, swimming, spinning, Pilates, etc.).

These routines are a work in progress, and I know that my ability to maintain them is strongly tied to my socioeconomic status and where I live. If I had more personal or financial stress, or lived in a different neighborhood with a long commute to work, I’d probably sleep less and eat more. I certainly wouldn’t be doing Pilates.

Research from the chamber won’t alleviate these socioeconomic drivers of obesity. But a better understanding of human physiology and metabolism — with the help of the chamber — might level the playing field through the discovery of effective treatments. As Lex Kravitz, an NIH neuroscientist and obesity researcher, told me, “Even if a slow metabolism isn’t the reason people become obese, it may still be a place to intervene for weight loss.” The same goes for the other common illnesses — diabetes, cardiovascular disease — linked to extra weight.

More immediately, science from the chamber should debunk our metabolism myths. It certainly debunked mine.

Christina Animashaun/Vox

For more about the metabolism chamber, listen to our Today, Explained podcast episode.

For more information about how to join a study at NIH, check out this link on patient recruitment or contact the NIH Clinical Center Office of Patient Recruitment at 1-800-411-1222 or [email protected]

Editor: Eliza Barclay
Copy editor: Tanya Pai

How can I speed up my metabolism?


Healthy weight

What can I do to speed up my metabolism?

It’s claimed that certain foods and drinks can boost your metabolism, including green tea, black coffee, spices and energy drinks. The evidence behind these claims is weak.

While you don’t have much control over the speed of your metabolism, you can control how many calories you burn through your level of physical activity.

The more active you are, the more calories you burn.

Some people who are said to have a fast metabolism are probably just more active – and maybe more fidgety – than others.

Here are the 3 most effective ways of burning calories:

Aerobic activity

Aerobic exercise is the most effective way to burn calories. You should aim to do at least 150 minutes of aerobic activity, such as walking, cycling and swimming, a week.

You can achieve this target by doing 30 minutes, 5 days a week and breaking down your activity sessions in chunks of 10 minutes.

To lose weight, you’re likely to need to do more than 150 minutes a week and make changes to your diet.

Read our physical activity guidelines for adults.

Strength training

Muscle burns more calories than fat, so increasing your muscle mass will help you lose weight.

Aim to do muscle-strengthening activities that work all major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms) on 2 or more days a week.

Examples of muscle-strengthening activities include lifting weights and high-intensity bouts of exercise. Heavy gardening may also do the job.

Be active

Try to make activity part of your daily routine. That could include walking or cycling all or part of your journey to work. You could also take the stairs instead of the lift.

Get ideas on fitting more activity into your day.

Boost Weight Loss by Knowing Your BMR

The easiest way to measure your BMR is to use an online calculator. These calculators factor in your height, weight, gender, and age, then assess how many calories you need to eat daily just to maintain your current weight at rest.

You can do the math yourself, using the appropriate equation:

Next figure out your total daily caloric requirement by multiplying your BMR by your level of activity:

  • If you rarely exercise, multiply your BMR by 1.2
  • If you exercise on 1 to 3 days per week, multiply your BMR by 1.375
  • If you exercise on 3 to 5 days per week, multiply your BMR by 1.55
  • If you exercise 6 to 7 days per week, multiply your BMR by 1.725
  • If you exercise every day and have a physical job or if you often exercise twice a day, multiply your BMR by 1.9

If the man in the example exercises 3 days a week, his daily caloric requirement is 1,734.4 x 1.55, or 2,688.3 calories.

If the woman in the example exercises 6 days a week, her daily caloric requirement is 1,357.4 x 1.725 or 2,342.5 calories.

This calculation gives you the number of calories you burn in one day at your current level of activity; this is the number of calories it takes to stay at the weight you are if you don’t change anything.

Applying Your BMR Calculation to Weight Loss

Once you know your BMR and the number of calories you burn for your activity level, you can improve your weight-loss efforts by setting a lower daily caloric-intake limit and crafting a plan for increasing your physical activity. Here’s how:

Set your daily calorie limit. To lose weight, you need to reduce your caloric intake below your total daily calorie requirement indicated by your BMR + activity level. Putting yourself in a 500-calorie deficit every day should result in the loss of one pound every week, Greaves says.

Adjust your exercise output. Calculators ask for your level of physical activity for a very good reason. You can influence your BMR through exercise, spurring your body to burn more calories even when you are just lounging about.

  • Aerobic exercise provides a temporary boost to your BMR, an effect sometimes referred to as after-burn or excess post-exercise oxygen consumption, says Noelle Lusardi, a certified personal fitness trainer who also works at the Step Ahead Weight Loss Center in Bedminster, N.J. This boost drops dramatically following an aerobic workout, with your BMR returning back to its normal level within 15 minutes to 48 hours.
  • Strength training provides a more lasting boost to BMR by altering your body’s composition. Muscle at rest burns more calories than fat at rest. That’s why men naturally enjoy a higher BMR than women, as they tend to have more muscle mass, Greaves explains.
  • Increase the calorie deficit by adding more exercise. If you increase the amount of calories you burn off by 250 each day, you’ll lose a half-pound more on top of the calorie cuts made in your diet. You can also increase the intensity of your workouts to burn more calories, and you will increase your calorie deficit and aid your efforts at weight loss.

The advantage of knowing your BMR is that you can adjust the number of calories of any diet you choose to meet your personal guidelines for weight loss.

Photo: Pond5

Think you need to run a marathon just to burn off breakfast, lunch and dinner? Think again. The human body requires a significant amount of energy (i.e. calories) just to function regularly. Each day, your body must breathe, blink, circulate blood, control body temperature, grow new cells, support brain and nerve activity and contract muscles. Staying alive is hard work, people! The amount of energy (in the form of calories) that the body needs to function while resting for 24 hours is known as the basal metabolic rate, or BMR. This number of calories reflects how much energy your body requires to support vital body functions if, hypothetically, you were resting in bed for an entire day. In fact, your BMR is the single largest component (upwards of 60 percent) of your total energy burned each day.

RELATED: 5 Intermittent Fasting Methods: Which One Is Right for You?

While you can’t magically change your BMR right away, knowing your personal number, how it’s calculated, and which factors most influence your metabolism, can help you use this data point to create a smarter strategy for weight loss (or maintenance).

BMR: Your Basic Burn

To most accurately calculate BMR, an expert takes measurements of carbon dioxide and oxygen analysis after a subject has fasted for 12 hours and has had eight hours of sleep. However, a rough estimation of this data is possible using the Mifflin-St. Jeor equation, a formula introduced in 1990. Since it’s proven to be more accurate than previous BMR formulas, the Mifflin-St. Jeor equation is now considered the standard when it comes to calculating BMR.

Mifflin St. Jeor Equation

For men: BMR = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) + 5
For women: BMR = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (years) – 161

“You’ll want to use a BMR as a rough estimate to set your basic needs,” says Dr. Jennifer Sacheck, Ph.D, an associate professor of nutrition at Tufts University and co-author of Thinner This Year. She notes that this won’t vary too much for a male or female of the same age and body weight. Why the emphasis on weight, height, age and gender?

Weight and height: “The more mass you have, the more fuel you need to sustain larger organs,” notes Dr. Sacheck, explaining why heavier and taller individuals have a higher BMR. When you lose weight, your BMR decreases and you require fewer calories per day. In contrast, when you gain dense, heavier muscle, your BMR will increase.

Age: According to Dr. Sacheck, metabolic rate decreases as you age because muscle mass declines by five to 10 percent each decade after the age of 30. Luckily, it’s not a certain fate for the over-30 crowd. “We can mitigate that when we’re engaged in strength training,” says Dr. Sacheck. She recommends circuit training that incorporates full-body resistance exercises (think lunges, squats, core work on a balance ball). “Strength training individual muscle groups in isolation won’t be as effective in strengthening your body for daily movement that always incorporates a mix of muscle groups,” she says.

Gender: Since body composition (ratios of lean muscle, bone and fat) differ between men and women, research shows a woman’s BMR is typically around five to 10 percent lower than a man’s.

Calculate Your BMR

Keep in mind, unless you have sophisticated tools to analyze your breathing or you’re closely monitoring your heart rate, you can’t calculate exactly how many calories you’re burning with exercise and digestion alone. Plus, Dr. Sacheck notes that stress levels and illness can also slightly or moderately change your BMR. Nevertheless, a formula-based estimate is a good place to start if you want to keep your diet in check.

RELATED: The 6 Best Ways to Measure Body Fat Percentage

Photo: Pond5

TDEE: Energy, Explained

Once you know your BMR, you can make a more realistic guess of your total daily energy expenditure, or TDEE. This reflects the entire amount of calories, or energy, your body burns during a given day when you’re sleeping, ingesting and digesting food, working and exercising. To truly reflect the energy you’re burning, TDEE takes into account two additional aspects.

1. Thermic Effect of Activity (TEA): This is the amount of calories burned while exercising. The more intensely your muscles are working — sprinting during intervals or flexing while lifting weights — the more calories you’ll burn. And if you’ve completed a higher intensity workout, your body will have to work even harder to replenish its oxygen stores, resulting in an afterburn effect known as EPOC.

2. Thermic Effect of Feeding (TEF): When you digest food and absorb its nutrients, your body uses energy in the form of calories. “It’s only roughly three to five percent of your daily calorie needs,” Dr. Sacheck says, noting that proteins and fiber have the highest thermic effect, meaning they require the most amount of calories to digest per calorie consumed.

So how do we put a number on our TDEE? Taking into account your activity level and BMR, the calculators below can give an approximation of how much fuel your body requires. Note: If weight loss is your goal, you’ll want to create a calorie deficit. Aim to consume 90% of your TDEE.

RELATED: 6 Reasons Why You Can’t Out-Exercise A Bad Diet

The Takeaway

Knowing your BMR is important no matter if your goal is to lose weight, gain muscle, run harder or even taper from a training plan. It’s the first step to getting an idea of how much fuel you need to keep your engine roaring all day long. The next step is determining which healthy meals match up with your TDEE and leave you satisfied and energized. But it doesn’t stop there! When your body fluctuates or you change your exercise routine, revisit the BMR calculator to know if you should be eating more or less. When in doubt, consult with your doctor or nutritionist to make sure you’re on the right track.

Originally published April 17, 2014. Updated September 2017.

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Looking for a BMR and TDEE calculator? You’ve come to the right place!

But first, what exactly is BMR and TDEE? Well, to lose weight using the calorie counting method you need to know just how many calories your body needs, in other words you need to calculate your Basal Metabolic Rate (BMR) and your Total Daily Energy Expenditure (TDEE). This gives you a calorie target which you can then cut calories from. Once you’ve created a calorie deficit, for every 3,500 calories you cut you should lose a pound of fat.

WARNING: This is not a precise science as there are so many variables at play. The simplest approach is to get your TDEE by using our BMR and TDEE calculator, create your calorie deficit and monitor your progress. If you are losing weight, it’s working! If you’re not losing weight, it’s time to rethink your approach – recalculate your BMR and TDEE and try a bigger deficit or ask for help in our weight loss forum.

Where can I find a BMR and TDEE calculator?

By far the best way to get your BMR and TDEE for free is to take our 3-minute Health Report, which is completely free.

STEP ONE: CALCULATE YOUR BMR

To get your BMR simply and we’ll calculate your BMR for you for free.

STEP TWO: WORK OUT YOUR TDEE

Take your BMR and multiply it depending on your activity level.

STEP THREE: FIGURE OUT HOW MANY CALORIES TO CUT

It’s up to you how many calories you take away from your TDEE. Put simply, if you eat fewer calories than your TDEE, you will lose weight. But this number needs to be sustainable, so try subtracting 500 from your TDEE – this gives you a good starting point and should result in decent weight loss.

Further reading

If you’re interested in the science behind BMR and TDEE and how these calculations will help you lose weight, have a look at this in-depth discussion.

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