Weight loss and tiredness

Tiredness & fatigue

Fatigue is the feeling of being tired all the time, even after you have rested. Most of the time fatigue is your body’s way of saying you need to make some lifestyle changes. However, sometimes it can be a sign of an underlying condition.

Key points

  1. Fatigue is common. One in 5 people feel tired most of the time and 1 in 10 people experience ongoing tiredness. Women tend to feel more tired than men.
  2. If you are getting enough sleep, exercise and healthy food, and generally have a healthy, low-stress lifestyle and are still experiencing fatigue, talk to your doctor.
  3. It is unusual for tiredness on its own to be a sign that you have a physical health condition. It is more likely to be a sign that some part of your life is out of balance.
  4. See your doctor if your tiredness is combined with heavy periods, weight loss, a change in bowel habits, hair loss or extreme thirst.
  5. Blood and urine tests can rule out medical reasons such as anaemia, diabetes or underactive thyroid.
  6. If a medical reason has been ruled out, try to identify stressors or events in your life that may have triggered or be contributing to your tiredness. See also our separate page on chronic fatigue syndrome.

Image credit: BBH Singapore, Unsplash

What is fatigue?

Fatigue is the feeling of being tired all the time. It is different from the feeling of sleepiness you get at bedtime or tiredness after exercise or a late night. Fatigue may be physical (in your body) or psychological (in your mind).

You are more likely to experience fatigue if you have a physical or mental illness or are on a low-income. Women are more commonly affected than men.

What are the symptoms of fatigue?

Fatigue can cause a wide range of symptoms.

  • Physical: feeling tired all the time, headaches, lightheadedness, sore, aching or weak muscles, loss of appetite, prone to getting sick.
  • Mental: slowed reflexes and responses, poor decision making and judgement, short-term memory problems, poor concentration.
  • Emotional: moodiness, irritability, low motivation, feeling depressed and hopeless.

What causes fatigue?

Most of the time fatigue is not due to one thing, but a combination of psychological, physical and lifestyle factors.


Psychological causes of fatigue are much more common than physical ones.

It’s common to feel fatigued if you are experiencing:

  • Anxiety– for example, worrying about something so much that it keeps you up at night.
  • Grief or emotional shock – for example, after the death of a loved one or a natural disaster.
  • Stress – including stress at work, juggling work and family commitments, low income, or even positive events, such as planning a wedding.
  • Depression – fatigue is a common symptom of depression.


It is common to feel tired when you are:

  • underweight, overweight or obese
  • pregnant or breastfeeding
  • sick or have a health condition such as anaemia, thyroid problems, coeliac disease or diabetes.
  • having cancer treatment such as chemotherapy or radiotherapy
  • taking certain medications – some medications and some combinations of medications can make you feel tired. The tiredness may improve as your body gets used to the new medication or new combination of medications. If you think your medication is causing fatigue, talk to your doctor. They may reduce or change your medication.


Fatigue can also be caused by lifestyle factors.

  • Drinking too much alcohol: Drinking alcohol in the evening tends to make you wake up in the middle of the night. Drinking too much on a regular basis can affect your mood and your sleep.
  • Having a disturbed sleep pattern: Going to sleep at the same time every night and waking up at the same time every morning helps set your body’s natural sleep-wake cycle.
  • Shift work, looking after small children or even just sleeping in on the weekend, can throw your normal sleep pattern off balance. This means your body wants to be sleeping at times when you need to be awake.
  • Drinking too much caffeine Caffeine is a stimulant that can stress the nervous system and cause insomnia.
  • Not exercising regularly: Keeping active every day is one of the best things you can do to reduce stress and anxiety, help you sleep better and improve your sense of well-being. It seems counter-intuitive, but tiring yourself out with exercise means you’re less likely to feel fatigued.
  • Poor diet: Foods high in sugar provide a short-term energy boost that quickly wears off, making you feel more tired. A healthy, balanced diet provides your body with the energy and nutrients it needs to function at its best.

When should I see a doctor about tiredness?

Tiredness + other symptoms

See your doctor if you have fatigue plus any of the following symptoms:

  • heavy periods
  • weight change
  • a change in bowel habits
  • hair loss
  • extreme thirst
  • any other symptoms concerning you.

These may be signs of an underlying medical problem.

Tiredness as main symptom

If tiredness is your main symptom, and you are getting enough exercise and sleep, eating a balanced diet and have a low-stress lifestyle and are still experiencing fatigue, see your doctor for a check-up. See also our separate page on chronic fatigue syndrome.

Questions a doctor may ask include the following:

  • Do you feel drowsy or weak?
  • Do you feel down or depressed?
  • Has your fatigue developed slowly or suddenly?
  • Is it cyclical or constant?
  • What do you think the cause might be?
  • Have you experienced any significant life events recently?
  • Is your life in balance? Consider work, relationships, physical, emotional, social, sense of worth and recreation.

Your doctor may also:

  • take your sleep history, including how much sleep you get each night, what the quality of your sleep is like, and whether you snore, wake or stop breathing in the night
  • do a physical examination to check for signs of illness or disease
  • carry out tests to rule out physical causes, such as blood and urine tests.

What is the treatment for fatigue?

If you have a medical condition causing fatigue, treatment will focus on the condition. If there is no medical cause, treatment will focus on lifestyle factors.

Talking therapy (counselling) may be useful if you:

  • are worried or anxious
  • have experienced a major life event
  • are feeling low or depressed.

Self-care for tiredness and fatigue

Reducing stress, caffeine and alcohol intake, getting more exercise and sleep, and giving your body healthy food to fuel it will boost your energy and reduce fatigue. Read more about self-care for fatigue.

Learn more

Sleep and tiredness NHS, UK, 2018
Tiredness and fatigue Patient Info, UK, 2017
Tiredness Royal College of Psychiatrists, 2015

  1. Fatigue and TATT Patient Info Professional, UK, 2019
  2. The laboratory investigation of tiredness BPAC, NZ

Reviewed by

Dr Sharon Leitch is a general practitioner and clinical research training fellow in the Department of General Practice and Rural Health at the University of Otago. Her area of research is patient safety in primary care and safe medicine use.

“I’m tired and gaining weight. Should I talk to my GP?”

Fatigue is a common symptom associated with many conditions. Since it doesn’t always have a clear medical cause, it can sometimes go underinvestigated. If you’re experiencing fatigue with no clear causes or lifestyle changes, you should see your healthcare provider for a complete medical examination – often referred to as a “workup” – to find out more.

Fatigue can be associated with underactive and overactive thyroid disease, usually appearing with more advanced cases. Another possible cause of fatigue is anemia, which is a deficiency of red blood cells or hemoglobin. But fatigue can also be due to other medical conditions, such as infections, inflammatory conditions, chronic diseases and menopause. In many of these cases, you need to be screened by your physician to figure out the cause.

Weight gain is another symptom associated with a number of medical conditions, including thyroid disease, although it isn’t as common. With an underactive thyroid, also known as hypothyroidism, your body’s metabolism and energy consumption slow down, which can result in gradual weight gain.

Why that scale might be rising

Other common causes of weight gain include a significant decrease in daily activity levels and menopause. It can also be the side effect of certain medications. If you’re at a genetically higher risk of obesity due to your family history, you could be gaining weight from any of the above-mentioned conditions.

In cases of fatigue or weight gain, you should let your doctor know what you’re experiencing and when it started. It’s also important to tell your doctor if you’re experiencing fatigue and weight gain at the same time. Your doctor may recommend a blood test to check your hormone, vitamin and mineral levels.

The first test for assessing your thyroid function is a thyroid-stimulating hormone (TSH) measurement through a blood test. Hypothyroidism is usually treatable, and if symptoms like fatigue and weight gain are related to an underfunctioning thyroid, they should improve in two or three months with treatment.

In the case of anemia, you would do a complete blood count (CBC) to check your levels of hemoglobin and ferritin and make sure that you’re not iron deficient.

One thing to remember is that, regardless of the cause of fatigue or weight gain, exercise is often an effective treatment. As always, if you’re thinking of starting a new exercise regimen, be sure to speak to your healthcare provider.

Dr. Afshan Zahedi is an endocrinologist at Women’s College Hospital. Follow them on Twitter at @WCHospital

Unintentional weight loss

Sudden, noticeable weight loss can happen after a stressful event, although it can also be a sign of a serious illness.

It’s normal to lose a noticeable amount of weight after the stress of changing jobs, divorce, redundancy or bereavement.

Weight often returns to normal when you start to feel happier, after you’ve had time to grieve or get used to the change. Counselling and support may be needed to help you get to this stage.

Significant weight loss can also be the result of an eating disorder, such as anorexia or bulimia. If you think you have an eating disorder, talk to someone you trust and consider speaking to your GP. There are also several organisations that can provide you with information and advice, such as the eating disorders charity Beat.

If your weight loss wasn’t due to one of the causes mentioned, and you didn’t lose weight through dieting or exercising, see your GP, as you may have an illness that needs treating.

The following information may give you a better idea of the cause of your weight loss, but don’t use it to diagnose yourself. Always see a GP for a proper diagnosis.

Fatigue & Weight Loss – Here’s how being tired is preventing you from losing weight

Are you feeling tired all of the time while trying to lose weight? Here are some tips to help you troubleshoot why this might be happening.

Are you feeling tired all of the time while trying to lose weight? Here are some tips to help you troubleshoot why this might be happening.

Are you getting enough sleep?

We often forget this basic need – good quality sleep and sleeping enough hours. If you do not sleep well and this seems to be a chronic (long-term) problem, please talk with your healthcare provider about what might be wrong.

Are you eating to boost energy?

If you feel tired and still need to be productive, try exercise instead of junk food to help boost your energy level. If you do just enough without overdoing it (e.g. walking), you might find it energizes you much more effectively than fatty and sugary carb snacks (candy, chips, pop).

Long gaps between meals?

If you tend to go more than 4-5 hours between meals, then consider including a snack as a stop-gap. Your body needs fuel. A weight loss plan that includes lower-calorie meals plus long time gaps between meals could set you up for low energy.

Are you eating enough?

Personalize your calorie target. We are all different – some adults can tolerate intakes of 1000-1200 calories per day without any issues, whereas others need to eat more to avoid feeling tired, irritable, or light-headed. If you track your intake, include notes about how you are feeling so that you can see patterns between food intake, timing, exercise, and overall energy level. If the calories deficit is so great that you can’t meet it without excessive hunger, then lower your weekly rate of weight loss to a slower rate.

Get enough protein. Aim for at least 60 grams of protein per day. If you eat 3 main meals per day, then aim for 20 grams of protein per meal. Include protein at snacks as well if you find that you are hungry between meals. This is especially helpful if you are reducing your calories intake for weight loss.

Don’t overly restrict carbs. If you are frequently feeling lightheaded, then check to see if you are undercutting your carbs too much. While it is useful to cut calories from junk carbs, do include healthy carb choices to keep your blood glucose at a healthy level. Some of us are more sensitive than others to low carb eating. Either high or low blood glucose can make you feel tired.

Exercise level okay?

Excessive fatigue can result from too little or too much exercise.

If you are getting up earlier to squeeze in exercise, go to bed earlier to avoid losing sleep hours.

If you suspect you are overdoing exercise, scale back a bit to see if it helps with your energy level. You might be doing too much in one or more areas: frequency, intensity, or duration.

If you work long hours in a sitting position, get up every hour and move. Find an excuse to walk somewhere.

A particularly bad combination is poor sleep and sedentary activity. That pretty much sets you up for overeating foods to stay awake.

How’s your stress level?

Long term, chronic stress can diminish energy and positive mood. Ideally, identify what is causing the stress and work to resolve or avoid it.

Many of us use comfort eating to handle stress. How will you handle stress now that you are trying to lose weight? Have a back-up plan. If you love to chew, then chew crunchy non-starchy veggies, sugar-free gum, ice, or something else that has minimal calories.

You could also try closing your eyes, and taking slow deep breaths. Take about 5 seconds to inhale and 5 seconds to exhale and do at least 3-5 full breaths.

Exercise can also help reduce stress – do it daily at especially stressful time periods. Or to “defuse”, take a walk at lunch and after work.

Chronic fatigue is a sign that something is not quite right. Please share what is happening with your healthcare provider if you can’t solve the problem on your own.

Originally published: 1 July 2014
Updated: October 2, 2019

Exercise->Health Weight Loss->Weight Loss Tips & Quips Other Health Issues->Energy & FatigueKatherine Isacks, MPS, RDN, CDE – Registered Dietitian and Certified Diabetes Educator (CDE)

What causes unexplained weight loss?

Several medical conditions can cause unexplained weight loss. People can help their doctor pinpoint the underlying cause by paying attention to any additional symptoms that they experience.

The following problems and conditions may cause unexplained weight loss:


Share on PinterestA person with hyperthyroidism may experience fatigue, muscle weakness, and difficulty sleeping.

Hyperthyroidism occurs when the thyroid gland produces more hormones than the body requires. People sometimes refer to this condition as an overactive thyroid.

The thyroid produces certain hormones that regulate the body’s metabolism, so an excess of these hormones often causes the body to burn more energy than usual. Burning more energy and calories can lead to unintentional or unexplained weight loss.

Other symptoms of hyperthyroidism include:

  • fatigue
  • tremor with shaking hands
  • muscle weakness
  • difficulty sleeping
  • rapid heartbeat
  • changes in mood, such as an increase in irritability or nervousness
  • diarrhea
  • a swelling in the neck, called goiter


The symptoms of depression can also cause weight loss.

In a 2017 prospective study, researchers examined the causes of unexplained weight loss in 2,677 adults. They identified depression as the underlying cause in 7% of the participants.

According to the researchers behind a 2016 study, there is evidence to suggest that people with depression may have associated suppressed interplay among the hypothalamus, pituitary gland, and adrenal glands, which may affect the function of the gastrointestinal (GI) tract.

Changes to the hypothalamus and pituitary gland can also affect the adrenal glands, which produce multiple hormones. These hormones include cortisol, which helps regulate blood pressure, blood glucose level, and metabolism.

Other symptoms of depression include:

  • persistent or recurring feelings of sadness, hopelessness, or apathy
  • changes in appetite, such as eating more or less than usual
  • unintentional weight loss or weight gain

Addison’s disease

Addison’s disease is most commonly due to a rare autoimmune disease that harms the adrenal glands and prevents them from producing enough cortisol and aldosterone.

People who have Addison’s disease might notice a decrease in their appetite as well as unexplained weight loss, according to the National Institutes of Health (NIH).

Other symptoms of Addison’s disease include:

  • fatigue
  • nausea
  • low blood pressure, or hypotension
  • dizziness
  • muscle cramps
  • abnormally darkened areas of skin, or hyperpigmentation
  • low levels of sugar and sodium in the blood
  • high levels of potassium in the blood
  • low red blood cell count, or anemia
  • high white blood cell count (leukocytosis), typically due to too many eosinophils

Inflammatory bowel disease

Share on PinterestAbdominal pain is a common symptom of IBD.

Inflammatory bowel disease (IBD) refers to two inflammatory gastrointestinal conditions with immune system dysfunction: Crohn’s disease and ulcerative colitis.

Crohn’s disease can cause inflammation in any part of the gastrointestinal tract, from the mouth to the anus. Ulcerative colitis, on the other hand, only affects the large intestine.

IBD can reduce the body’s ability to digest food properly or absorb nutrients, which can lead to malnutrition.

Weight loss is a common symptom of both conditions, especially among younger people. Other symptoms of IBD include:

  • frequent diarrhea
  • abdominal pain
  • bloody stools due to GI tract bleeding
  • fatigue
  • fever

Muscle loss

Muscle loss, also known as muscle atrophy, occurs when the muscles shrink or waste away. This condition can cause unexplained weight loss.

Possible causes of muscle loss include:

  • inactivity due to an injury
  • malnutrition
  • aging
  • a stroke
  • multiple sclerosis (MS)
  • amyotrophic lateral sclerosis (ALS)

People can often prevent muscle loss through proper nutrition and regular exercise. Physical therapy after an injury or stroke may help reverse or prevent muscle loss.

Rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disorder that causes inflammation in the joints.

Although the Arthritis Foundation estimate that two-thirds of people who have RA are overweight or have obesity, people who have RA may experience weight loss.

This weight loss may occur because the chronic inflammation that RA causes forces the body to use more energy. In addition, people who have RA may experience muscle loss because the inflammation in their joints keeps them from engaging in regular physical activity.

Some medications that people take to treat RA may cause side effects, such as diarrhea and loss of appetite, which can also contribute to weight loss.


Although cancer symptoms tend to vary depending on the type, stage, and location of the disease, unexplained weight loss is sometimes a sign of cancer.

Cancer refers to any disease in which abnormal and mutated cells rapidly multiply and eventually invade healthy tissue.

Weight loss is especially common in lung cancer and cancers that affect the digestive tract, such as:

  • pancreatic cancer
  • colorectal cancer
  • liver cancer
  • stomach cancer
  • bile duct carcinoma
  • esophageal cancer

Other early symptoms of cancer to pay attention to include:

  • fatigue
  • fever
  • pain
  • digestive issues
  • changes in bowel or bladder function
  • skin changes
  • a persistent cough

Other possible causes

A person may also experience unexplained weight loss as a result of:

  • kidney or liver disease
  • alcohol or drug use disorder
  • a stomach ulcer
  • celiac disease


Often, a patient will share that he or she struggles with a slow metabolism and has trouble losing weight. I sympathize but almost always respond that the metabolism is flexible and with the right strategies, it can be optimized.

To understand why, I need to go into a little biochemistry.

Everyone was born with a different biochemical makeup. You have trillions of little energy factories that are cellular organelles called mitochondria that help your body run. Mitochondria convert the oxygen you breathe and food you eat into energy your body can use.

Think of mitochondria as cellular combustion engines. Having effective mitochondria means your body efficiently burns calories and you have a fast metabolism. Ineffective mitochondria don’t burn calories and slow down our metabolism.

In all fairness, some of this is genetically determined. Research shows if you have a parent or sibling who has type 2 diabetes, even if you’re thin, your mitochondria are 50 percent less effective at burning calories than the average person.

These predispositions mean you’re more likely to gain weight and eventually develop diabetes, or what I collectively call diabesity, which subsequently adversely affects your mitochondria.

Likewise, aging itself and other chronic diseases like heart disease and dementia create mitochondrial dysfunction.

However, the biggest hit comes from your diet. Food is information that tells your cells and mitochondria what to do. When you eat lots of sugar and processed, inflammatory foods including refined oils or simply consume too much food, period, you overload your energy factories and damage results.

Likewise, starvation mode means your body clings to fat. After all, your body’s big priority involves keeping you alive, not fitting into a bathing suit when summer arrives. I’m sorry to say that your body has become extremely well-adapted to holding on to fat.

That doesn’t mean you can’t take control. To optimize mitochondria, you want to eat the right kinds of foods and eat enough of those foods.

Other things that affect your mitochondria include environmental toxins, hidden infections, stress, and gut microbiome imbalances.

Fortunately, you can increase the number and function of your mitochondria with these five strategies:

Does Losing Weight Make You Tired?

Shedding extra weight that you have put on lowers your risk health problems such as diabetes and heart disease. But can it prove to be detrimental for your stamina? In any case, losing weight by diet restriction has never been considered ideal as it leaves you feeling tired when you want to be rejuvenated. You need to choose a diet plan after consultation with a nutritionist or your health care provider to start a diet that is suitable for your body.

So, does losing weight make you feel tired?
Adverse effects of having too little calories

People who starve themselves by dieting soon realise that all their effort was futile. The insufficient calories that they consume may make them lose weight rapidly but it results in fatigue. Lack of concentration, apathy, depression, anxiety and irritability can also occur. Low calorie intake affects your muscle structure and even your heart is a muscle.

So, it gets affected by deficiency of calories leading to problems in pumping blood to all your body parts and the eventual low blood pressure. Tiredness and feeling dizzy are two major symptoms of low BP. A diet low in calories also depletes the essential vitamins of the body through water loss.
Know your ideal weight

You should learn about your ideal weight and look to maintain it. Do not go by the height and weight measurements of insurance companies. Everyone of a specific height would not necessarily have a particular weight. It is natural that this varies. Each individual is built differently and in some the body shape is such that they are more adept in carrying more weight without it being unhealthy.

Moreover, bear in mind that fit women actually weigh more because of the weight of their muscles. Muscles weigh more than fat. So, even though a woman shows normal weight on the scale but if she has high levels of body fat, she cannot be called healthy. That is why you should give due importance to the BMI (body mass index) rather than any arbitrary weight measure when looking to lose weight.
Imbalance of carbohydrates, proteins and fat

If the diet plan you embark upon is not based on inclusion of adequate amount of macronutrients, i.e. proteins, fats and carbohydrates, it can lead to fatigue. If your diet is too high on protein but does not provide enough carbohydrates, losing weight would make you feel tired. This is because it leads to excess fluid loss from the body. Your muscles would lose glycogen, the major source of energy supply for them. This would naturally lead to fatigue. So, while focusing on protein, it is recommended that you make sure that you get enough of carbs. Protein helps to convert food into energy while fat is needed as a reserve of energy. Fat content of your food should be restricted to 30 per cent of calories consumed.

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