5 Reasons Rapid Weight Gain Happens In Chronic Fatigue Syndrome

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What Everyone Should Know About Weight Gain In C.F.S

While suffering from chronic fatigue syndrome it is not uncommon to gain quite a bit of weight. My personal experience with this illness saw my weight increase by 12 kilos (just over 26 pounds).

Alarmingly, I experienced rapid weight gain in a short period of time when my illness progressed to its later stages.

12 kilos may not seem like a huge weight increase. But on a person with a small frame this amount of excess weight was substantial. As someone who has always exercised and worked hard to maintain a healthy body weight, carrying this unwanted weight was devastating.

reasons rapid weight gain happens

No matter how I tried to maintain a healthy diet my body was seemingly working against me, and the excess weight kept piling on. This uncomfortable weight gain added to my many other symptoms making me pretty miserable with this debilitating illness.


My stubborn weight gain didn’t begin to disappear until I started working with my naturopath. Before starting on the work to uncover the root cause(s) of my illness my alarming weight gain kept increasing at a rapid rate.

However, once I was on the road to recovery, slowly but surely my weight started to normalize. As always though, it took much longer for the weight to reduce than it had to put it on. But this experience made me wonder about the reasons rapid weight gain happens when you have this baffling illness.

Chronic fatigue syndrome affects the metabolic system making it easy to gain weight and almost impossible to lose it, until correct treatment suited to each individual’s case is followed.

For many people making alterations to your diet is not enough to lose weight and keep it off. Your body systems are simply not working individually and in concert together.

It is reported that the average weight gain for chronic fatigue syndrome sufferers is approximately 30 pounds. The double whammy effect of disruption to your metabolism from the illness coupled with being less active due to horrible fatigue has a devastating effect on your weight. Not being able to carry out your normal exercise routine delivers another blow.

5 Reasons You Can’t Lose Weight With Chronic Fatigue Syndrome.

1. Poor Sleep Quality

Chronic fatigue syndrome sufferers commonly have sleep difficulties. You may wake up several times during the night, or regularly have trouble getting to sleep at all. This sets in place a constant pattern of poor quality and inadequate sleep.

A study shows sleep deprivation may influence weight via its effect on appetite, activity and thermo regulation.

Sleeping deeply improves insulin sensitivity helping your cells respond to insulin and decreasing the tendency to store body fat. Deep restorative sleep also triggers growth hormone which helps burn fat and create muscle production.

It is important to get between 8 and 9 hours sleep every night. The importance of sound good quality sleep cannot be overstated. reasons fr rapid weight gain - lack of sleep

When you are deprived of sleep your body experiences several changes that can lead to weight gain. Sleep deprivation causes changes to occur in the hormones that regulate your appetite and hunger response.

Lack of sleep reduces the hormone leptin which is the hormone responsible for suppressing your appetite. At the same time this is happening, another hormone, ghrelin responsible for triggering hunger, unfortunately increases.

Low energy levels caused by sleep deprivation makes all the wrong foods seem more appealing. Your body createscravings for sugar and fatty foods in an attempt to gain energy quickly.

2. Poor Diet + Uncontrollable Cravings For Sugar And Carbs

reasons for rapid weight gain burger

Whilst your body is desperately trying to create enough energy from a lack of good quality sleep, you may have uncontrollable cravings for sugar and high carbohydrate foods, anything to give you a lift and increase your energy level.

Added to this, in your fatigued state, your brain is unable to make clear and reasoned decisions about food choices. In this state you are more inclined to give in to junk food cravings.

Understanding that the cravings are your body’s way of crying out for the nutrients it needs for energy production can make it easier to acknowledge what causes the cravings and manage them.


ALL STIMULANTS – Including coffee, tea and caffeinated drinks. During the late afternoon when energy levels lag healthy people commonly use stimulants such as coffee and tea to provide a quick energy boost. For most, the thought of starting the day without a strong coffee is unfathomable.

But in those with chronic fatigue syndrome using this type of stimulant can make your symptoms worse. Caffeine pushes your adrenals to work harder. It can also cause existing sleep problems to become worse.

SUGAR (NATURAL + ARTIFICIAL) – When energy levels are low, particularly in the late afternoon, many people with chronic fatigue syndrome reach for a quick supply of sugar and carbs to boost their falling energy reserves. However, eating sugar laden snacks full of simple carbohydrates only makes the problem of low blood sugar worse.

This is because carbohydrate metabolism in chronic fatigue syndrome sufferers is disturbed. The temporary rise in blood sugar from eating sugar laden snacks is followed quickly by a plummet. This reduction in blood sugar starts a vicious cycle causing further mental and physical exhaustion to an already fatigued system.

FOOD ADDITIVES – Such as MSG, food preservatives, artificial colors and flavors. Chronic fatigue syndrome sufferers are generally sensitive to these chemicals. They can suffer from headaches, itching, worsening of pain symptoms and general allergic reactions. MSG can also cause extreme insomnia in those with the illness as it acts as an excitory neurotransmitter.

FOOD YOU ARE SENSITIVE TO – If you suspect food sensitivities could be a problem for you, testing should be carried out to identify offending food types. A wide and varied range of symptoms can be caused by food sensitivities.

Some include rashes, watery eyes, sneezing and runny nose, anxiety, headaches and joint pain. Fortunately, making a few simple changes and cutting out offending foods can make a huge difference in reducing your symptoms.

Food sensitivities often fall into groups, making identifying offending foods fairly easy. The most common symptom-producing foods include:

FOODS CONTAINING YEAST – This includes fermented foods which are generally great for gut health. But in people with yeast sensitivities some fermented foods need to be avoided. Fermented vegetables, alcohol, kefir, kombucha, aged cheese and bread containing yeast are all off the list.

THE NIGHTSHADE FAMILY – Tomatoes, eggplant, potatoes and peppers. This is a food group which commonly causes sensitivities in many people.

DAIRYLactose intolerance is another common food intolerance and it can produce ut discomfort like gas and bloating.

ALCOHOLIs also off the list because intolerance to alcohol is very common among people with chronic fatigue syndrome. Even small quantities can make them feel quite ill.

The central nervous system in those with chronic fatigue syndrome can be over active and alcohol acts directly on this system. Liver function in chronic fatigue can be less than optimal and alcohol works adversely on the liver.

GLUTEN – Many people with chronic fatigue syndrome do better by avoiding gluten containing food. Gluten can be responsible for many gastrointestinal symptoms like bloating, diarrhea, heartburn and constipation.

FOODS YOU SHOULD EATwhy am I suddenly gaining weight - health diet

People with chronic fatigue syndrome need to eat sensibly by choosing a balanced and healthy diet. Your diet needs to supply the basic raw materials and nutrients to help you produce much-needed energy. If you have sensitivities to particular foods these will have to be eliminated for a while to give your body a rest.

If you have increased weight during your illness you should not think about ‘weight loss diets’ which can place additional stress on your body.

Rather, focus on eating food that supports you and supplies much-needed energy in a natural way. Once you start to recover you will find weight loss starts to happen naturally as your body returns to a more harmonious state.

Your naturopath or functional medicine practitioner will guide advise you on the best diet for your particular circumstances. Generally a diet that includes unrefined carbohydrates, organic fruit and vegetables, grass raised poultry and meat as well as healthy fats provides a good foundation.

Choosing organic produce where possible will reduce the additional burden of unwanted chemicals, hormones and pesticides. Try to eat as ‘naturally’ as possible by avoiding packaged and processed foods.


3. Poor Adrenal Health

Experiencing chronic stress leads to the adrenals constantly releasing cortisol. High levels of cortisol lead directly to weight gain. rapid weight gain muffin topIn particular this type of weight gain shows up around your midsection as the body lays down fat around vital organs as a protection mechanism.

You will notice this sudden weight gain in stomach areas and you might find you now have a ‘muffin top’.

This ‘muffin top’ type of fat is very typical of adrenal fatigue. I didn’t have a roll of fat in that location until I developed adrenal fatigue.

When the adrenal glands become exhausted due to over stimulation from stress you can end up with hypoglycemia (low blood sugar). Symptoms of hypoglycemia can manifest as cravings for sugar as the body tries to raise your blood sugar level.

Some people indulge in sugary foods when dealing with hypoglycemia contributing further to weight gain. This also leads to a roller coaster of highs then crashes in blood sugar levels.


A catabolic hormone, cortisol is released by your adrenals during stress and it breaks down protein for use as energy. So even if you are working out you can be experiencing ongoing muscle wastage.

With less muscle you lay down more body fat. Cortisol is also released during exercise and if you work out at high intensity there is a bigger cortisol release.

Insulin controls blood sugar and cortisol has a delicate relationship with it. When cortisol levels become elevated, our body can become resistant to insulin. This can lead to increased blood sugar and weight gain. It can also potentially pave the way for Type 2 Diabetes.

In adrenal fatigue cortisol levels drop greatly. As this happens blood sugar levels can decrease, causing hypoglycemia. This is linked to a low tolerance to stress and weight loss.

However, high and low cortisol levels can cause symptoms of low metabolism resulting in feelings of fatigue and cognitive issues like brain fog. In order to prevent rapid weight gain it’s important to control your cortisol.

4. Poor Thyroid Health

Sometimes there is a thyroid component to your chronic fatigue syndrome which shows up as inadequate levels of thyroid hormone produced by the body. This can adversely affect weight control because the thyroid gland produces hormones that control the speed of your metabolism.

rapid weight gain thyroid

An under active thyroid can slow down metabolism by disrupting the production of thyroid hormones. One of the symptoms of hypothyroid is weight gain due to inadequate hormones being produced by your thyroid gland.

Until, the thyroid imbalance is treated it is often impossible to lose weight. In addition, your adrenal health is closely related to thyroid function.



In my experience you have to heal your adrenals first before you can expect any improvement in your thyroid health because the adrenals and thyroid are closely connected.

During the process of becoming hypothyroid, before your TSH is elevated enough to show up on test results, your metabolism can already start slowing down substantially. This in turn results in burning fewer calories each day.

Some symptoms of low thyroid to watch out for are muscle aches and pains, cold extremities, hair loss and ongoing fatigue. Dealing with these symptoms make it more difficult to exercise which in turn further reduces your metabolism.

Thyroid health can be treated by replacement with thyroid hormones. However, even with this treatment weight loss is not triggered. I have treated my hypothyroid condition nutritionally at the same time as healing my adrenals and found this combination ultimately successful.

5. Poor Gut Health

There are several reasons your gut goes out of unbalance. And an imbalance of gut bacteria i.e., the wrong type of microbial diversity, can affect numerous body systems including weight control.

reasons rapid weight gain gut health

Everything starts in your gut and among its many functions, your gut controls blood sugar balance, fat storage, and fat regulating hormones. All are important processes that can contribute to weight gain.

Your gut is very hard-working, it constantly processes nutrients, toxins, microbes, and chemicals that pass through your body via your digestive tract.

As 80% of your immune system is located in your gut it works hard to optimize your immune system keeping out harmful substances.

These are just some of the roles which depend on a healthy and balanced gut flora.


Imbalance between good and bad gut microorganisms (dysbiosis) means the bad guys are outnumbering the good guys. As this happens your gut doesn’t work properly. You don’t digest food well and you don’t eliminate waste properly. Your gut isn’t able to effectively communicate with your brain to signal it to stop eating which leads to overeating and weight gain.


A very common gut issue is a yeast (candida ) overgrowth. If present it can cause intense cravings for sugar as the yeast needs sugar to grow. The intense cravings you experience is the yeast sending signals for you to keep feeding it what it needs.

Among other reasons, yeast overgrowth can be caused by antibiotic use and excess sugar consumption. Several anti fungal herbs can be used to eliminate yeast overgrowth including olive leaf extract, pau d’ Arco, barberry and oregano oil.

Once you are able to kill off a large proportion of the candida yeast, your sugar cravings should reduce substantially.


A gut parasite infection is generally thought of as a short term infection that can cause digestive upsets like diarrhea, fever and general malaise. However, the parasites can persist past the initial infection once the original symptoms are gone.

Parasites can be responsible for various health problems, including weight gain. They consume the food we eat including the nutrients, robbing our bodies of these vital substances. In addition they also damage the gut membrane which prevents nutrients being absorbed properly. This in turn affects the way hormones, blood sugar and metabolism works.

Elevated blood sugar levels, out of balance hormones and sluggish metabolism, all lead to you being nutrient deficient making weight gain impossible to avoid.

Parasites disrupt the balance of your microbiome. Even a small change in just one strain of bacteria in your microbiome can cause weight gain. This change to the gut environment encourages candida yeast overgrowth and the resulting symptoms are bloating, gas, pain and fatigue as well as the weight gain.

Putting It All Together

Check out the 5 reasons you can’t lose weight outlined here. As, you read through them it will become apparent that they are interconnected. Our body systems influence each other. When one system gets out of sync it affects the others.

Carry out appropriate testing for adrenal, thyroid, food sensitivities and gut problems if you think these could be issues for you.

Review your eating and make sure you follow a healthy diet free from sugar and junk foods while taking some gentle exercise depending on your current fatigue level.

Please feel free to leave a comment or ask me any questions.


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  1. Hey Ann,

    My best friend is suffering from chronic fatigue syndrome and he has gained a bit of weight, I think 15 pounds over the span of half a year.

    I will send him over this article to take a look at as it might help him a bit.

    Do you have any articles on how to combat CFS and weight gain?

    Thank you!

    • Hi there and thanks for your comment. I’m sorry to hear your friend has chronic fatigue syndrome. Unfortunately I don’t have any articles about combatting weight gain in CFS as you really need to get to the root cause(s) of the CFS before weight begins to normalize. As the cause(s) of CFS is different for each individual there’s no one way to lose weight. However, keeping to a healthy anti inflammatory diet free from pasteurized dairy, gluten, grains refined food and sugar could help. 

    • The books ‘Medical Medium’ and ‘Thyroid Healing’ by health guru Anthony William best explain CFS and the metabolism issues related to it, and how to reverse them. Then after reading them, google ‘Cincinnati Hospital EBV’ study.
      Stanford University is studying CFS, and UMN is working on a vaccine for several of the older known strains of the virus thought to cause Mono & CFS, but there are dozens of newer mutations. The difficult part is that no two people have the exact same symtpoms, even twins.
      As we all know, funding for viral research is EXTREMELY low in the U.S., and Western Medicine’s allopathic cures for viral based diseases (like the Common Cold or Mono) have not improved much in the past 100 years.

      Interestingly, Chinese Medicine (TCM) has been curing them for thousands of years. Under their elemental science of years ago, they call them ‘Wind’, or ‘unseen force’. Their doctors only got paid AFTER a person got better, so their healers worked harder! The cure is mainly a healthier diet, removing stressors (such as toxins or toxic people), rebalancing the body to it’s natural and best state, and thus boosting the natural immune system, putting the underlying virus (which now, after 100+ years, almost every adult worldwide carries at least one strain of, out of dozens) back into a dormant state. AW’s books bring those principles into modern times.

  2. thanks for this lovely article; I have been trying to slim down for a long time but all is not working out for me; reviewing your article has made me learn alot and i can say this is an eye opener for me.

    The five reasons you oulined are very essential which i have taken note of, and i will make sure i work on them

    • Ola I hope this article helps you with your chronic fatigue syndrome. Unfortunately you will be unable to lose weight until you address the root cause of your chronic fatigue syndrome. 

  3. Hi! This is a very useful post! I greatly appreciate you have outlined these 5 reasons we can’t lose weight.

    I personally believe I must pay more attention to the first two you mention here. Sleeping plays an important role in our health. And our diet is also crucial. I’m grateful for your encouragement concerning foods we should eat. I have already started to eat as ‘naturally’ as possible, avoiding packaged and processed foods.

    Thank you very much!

    • Hi Henry I’m glad you found this information helpful. Sleep is very important to helping with weight loss and maintaining body weight. 

  4. That is truly fascinating that chronic fatigue syndrome can cause rapid weight gain. I know that when people are tired they often eat more but I didn’t know its an official side effect. Poor you, 12kg is a huge amount, that must have been very upsetting for you. I’m happy to hear you got it under control. How does one know if they have chronic fatigue syndrome?

    • Hi Hollie thanks for stopping by. Yes the whole journey with chronic fatigue syndrome was horrible and the weight gain added to the misery. However I’m so grateful I was able to recover. 

      Chronic fatigue syndrome is difficult to diagnose as the only method is to exclude other illnesses first. One of the main identifying symptoms is unrelenting fatigue that does not improve with sleep.

      In other words you go to sleep exhausted and wake up exhausted. Also you suffer post exertional malaise which means even the slightest activity hits you hard and can take several days bed rest to recover from. 

  5. Sorry for hearing that. But I love you more, why? Because you didn’t allow that to stop you from becoming or achieving what you want. And taking the effort to share your story and situations to educate others and how to overcome that. Girl, you awesome and thank you for that. 

    Everything, you have said in this article is so true. Even so true with a person who is not having chronic fatigue syndrome. Our metabolism determines how fast we loose and add weights. But once disrupted, the only thing you see is adding weight easily and quicker than you can loose it.  Like you said in those five points, they are few of many reasons that disrupt our metabolism. Thank you 

    • Hi Augusta, thanks so much for your kind words, it means a lot. I do try to share my experience in the hope it can help others suffering from this debilitating illness. So many people think there is no hope of recovery. I’m glad you found my post useful. 

  6. Wow, just wow! I read each part of this post a good few times over. I have been struggling with fatigue for quite a few months now, but after having some extremely bad experiences with doctors, I have gone to get tested. I am currently saving money to go to a plant based naturopath who does live blood testing, but all of what I read in this article made so much sense. I am eating as well as I can, but the cravings I get are ridiculous, I don’t sleep well, and I’m always so fatigued I feel like I can’t function. I gave up coffee (my only source of caffeine, aside from a random bit of chocolate every few weeks), that made a huge difference to the extent of my fatigue, just not enough that I feel like I have energy. Thank you so much for sharing this info, it’s really helped me get a better understanding of what’s going on in my body.

    • Hi Josie, it sounds like you’ve gained some useful information. Have you had your adrenals tested? Saliva testing will let you know your cortisol levels at different times of the day. It can show if your adrenals are stressed. 

  7. Wow, lot of information. I hadn’t really thought about it before but of course all these body systems are linked.

    I and I suppose others look at symptoms, find a cause and take medication without considering how closely it could be linked to and affected by other things.

    I knew about wheat allergies (gluten) and dairy but not about the nightshade family of foods or the yeast products. We hear about fermented foods especially, as being really good for gut health. 

    A really informative post that gives a lot of food for thought. Shows too, how important good nutrition is. Thank you.

    • Linda, thanks for taking the time to read my post and leave a comment, it sounds like you got some benefit from the info. 

  8. Weight gain is also something that I have had to deal with while suffering from Chronic Fatigue Syndrome. This was also true with my mother, who also went through the many issues and problems associated with the disease. At that time, it was not even recognized as a disease, actually, so there little guidance as to how to get treatment.

    The reasons you mention for the difficulty losing the weight you pick up read like my own story. Problems with sleeping, the cravings for sugar and carbs (in my case potato chips), the adrenal health (or lack thereof), the thyroid and gut issues are all ways that the disease manifests itself in me.

    You have offered some real and actionable solutions in each of the areas, and I will be paying close attention as I try them out to see which will have the most positive effect on my weight. I am so glad to have remained on your website today to do a bit more exploring. Thanks once again for your work to get this useful information out to all. 

    • Hi Dave, thanks for stopping by, I’m so glad you found my information useful. Drop by again and let us know how you go. 

  9. Hi Ann, thanks for this post. I did know that chronic fatigue could cause weight gain but I never knew the details of how. Talking of having enough sleep, I’m very guilty of not having enough sleep. I am not working at losing weight but I definitely do not want to gain any weight. I will be looking at my schedule and create more time for sleep. 

    • Thanks for leaving a comment Juliet. It’s becoming increasingly well known that poor quality sleep can contribute to weight gain. So many people these days simply don’t get enough sleep. 

  10. I am beginning to suspect my daughter has had CFS for the past two years. We have taken her to 4 naturopathic doctors, and none of them have been able to help her. All her tests turn out pretty normal. But she is absolutely exhausted and feels hungry constantly. She has great self-control and can stop eating but then she feels horribly exhausted and like she is going to faint. She cut out all carbs for a couple weeks trying to lose weight and could barely go to work, though she did lose a few pounds. She gets worse (hungrier and tireder) during her period. She started gaining weight only a few months ago, when she stopped working due to covid and therefore wasn’t as active. She can’t exercise much because she crashes afterwards. She’s tried all different diets and now I’ve ordered some herbs for her but she doesn’t want to try any more doctors because none have helped. I’m not sure how to figure out what combination of supplements she needs. Any suggestions? She’s twenty.

  11. Check out also your ferritine level and how much there is iron in the cells (ferritine can rise high if you have infection in the body).
    Without iron, the thyroid gland doesn’t work and you gain weight. It needs also sufficient amount of cortisol, and some other like iodine.
    Iron deficiency is quite common in women who have got periods.

    Also check out for other deficiencies, like vitamins B12 and D.


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