Metabolic Health 14 MIN READ

Chronic Fatigue Syndrome & Metabolic Health

Chronic fatigue syndrome (CFS), or myalgic encephalomyelitis (ME), is a complex health condition that affects multiple body systems and a gamut of bodily functions. CFS is difficult to diagnose, given that symptoms vary widely.

Written by Judy Balan

Oct 14, 2022
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Chronic fatigue syndrome (CFS), or myalgic encephalomyelitis (ME), is a complex health condition that affects multiple body systems and bodily functions. CFS is difficult to diagnose, given that symptoms vary widely. However, extreme fatigue that interferes with proper day-to-day functioning, pain, sensitivity, and a general sense of feeling unwell are distinguishing features.

Previously, this was considered a controversial diagnosis because of the lack of clarity on its causes. Even though CFS is widely accepted as a biological illness, there continues to be a lack of proper understanding of the condition. This is attributed to varying clinical diagnostic definitions, a wide range of presenting symptoms, no single underlying cause, and the absence of a laboratory test for diagnosis.

Let’s look at what we know about chronic fatigue syndrome:

  • CFS is more than just feeling tired all the time. The acute fatigue associated with CFS worsens with the most basic daily activities, such as doing the laundry or walking to the grocery store, and does not go away with rest.
  • Fatigue and symptoms, once triggered, last at least six months and could go on for years.
  • CFS can affect people of all ages, but women and young to middle-aged adults are most at risk.
  • Though the cause of CFS is unknown, the general consensus is that a lot of factors might be responsible for it. These could be viral infections, immune system problems, hormonal imbalances, emotional trauma as well as psychological and environmental stress.
  • Since there is no diagnostic test for CFS, it involves observing the symptoms and ruling out other conditions that could be causing them.
  • Treatment for CFS is focused on relieving symptoms. The treatment plan usually depends on how one is affected by CFS.

Symptoms of CFS

While the list of CFS symptoms is long and varied, there are three primary symptoms required for diagnosis:

  • Incapacitating fatigue that results in a significant decrease in physical activity and lasts six months, sometimes even years. There is a 50% drop in activity even in mild forms of CFS.
  • Sleep and rest do nothing to lower fatigue. Some people with CFS also have difficulty getting a night of restful sleep.
  • Aggravation of symptoms after certain physical or mental activities that would not have been a problem prior to the onset of CFS. This is known as post-exertional malaise (PEM).

These core symptoms aside, there are two other key CFS symptoms, one of which is required for diagnosis:

  • Difficulty in thinking quickly and clearly, staying focused, taking in details, and remembering things. This is often described as ‘brain fog’ by CFS patients.
  • Intensification of symptoms due to standing or sitting upright, known as orthostatic intolerance. Common complaints include dizziness, weakness, and changes in vision (such as seeing spots or blurry vision).

Other common symptoms of CFS

Below is a list of symptoms that affect many but not all CFS patients:

  • Headaches
  • Tender lymph nodes
  • Muscle and joint pain
  • Mood swings
  • Confusion
  • Low-grade fever
  • Depression
  • Irritable bowel syndrome

CFS and the nervous system

The nervous system is central to the human body and its processes. It controls everything we think, say, feel and do. It is in charge of both voluntary processes, such as movement and memory, and involuntary functions, which are things the body does without our conscious volition, such as breathing, blinking, digestion, and the beating of the heart.

It is divided into two systems: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS comprises the sympathetic nervous system, which monitors the body’s ‘fight or flight’ response, while the PNS is responsible for promoting relaxation.

What is the autonomic nervous system?

The involuntary branch of the PNS, the autonomic nervous system (ANS) , determines how many of the body’s processes operate on auto-pilot.

Like the CNS, the ANS also comprises a sympathetic (SNS) and parasympathetic nervous system (PNS). While the SNS puts the body on high gear, speeding up processes and preparing for ‘fight or flight,’ the PNS is known for the ‘rest and digest’ mode, slowing down the system and calming the body down. When in balance, these two systems work together in a complementary fashion, but they cannot both function at the same time.

The dysfunctional autonomic nervous system in CFS

According to a summary review published by The ME Association, existing evidence suggests that ANS is ‘out of balance’ in CFS/ME patients, a condition called dysautonomia. Robinson et al. (2015) found dysautonomia in almost 90% of CFS patients.

An imbalanced autonomic nervous system also affects the length and quality of sleep—a primary symptom of CFS/ME. According to a study by Boneva et al. (2007), there is evidence suggesting increased sympathetic activity is most prominent in patients with CFS/ME during sleep.

An overactive sympathetic system drains the body of energy and according to a study by Fisher et al. (2010), has been associated with cognitive decline, inflammation and increased pain, which play a major role in CFS/ME.

As we’ve already seen, the sympathetic and parasympathetic systems cannot function together, so CFS/ME patients tend to have ‘sympathetic nervous system predominance’, which means reduced parasympathetic activity and increased sympathetic activity ‘ (Martinez et al. 2014). While said ANS dysfunction can occur in healthy people after they engage in particularly strenuous activity, in CFS, the dysfunction sets off after much lower levels of stress or activity.

There is a marked hypersensitivity in CFS/ME to everything from infections and pain within the body to external stimuli such as noise, light, heat, and emotional stress. The body gets fixated on the ‘fight or flight’ response, which depletes energy and leads to other problems such as gastrological symptoms since digestion is not a priority in this state. When the SNS is in the driver’s seat, multiple organs and body processes go into overdrive, making it impossible for the body to relax.

Unfortunately, there is no easy fix or wonder drug for ANS dysfunction. The vagus nerve, a large nerve at the back of the head that controls parasympathetic activity (‘rest and digest’ mode), may offer a way forward.

Vagal tone is a measure of cardiovascular function that aids adaptive responses to environmental challenges. Low vagal tone, associated with a lack of emotional and attentional regulation and a marker of sensitivity to stress, is commonly seen in CFS/ME and other chronic illnesses. So increasing vagal tone can increase parasympathetic activity, which can help lower symptoms.

Medical innervations to increase vagal tone and reset ANS by stimulating the vagus nerve are invasive and not widely used. However, self-help techniques to induce relaxation, such as deep diaphragm breathing, mindfulness/meditation, humming or singing, muscle relaxation, and laughter, among others, have been reported as being helpful.

What is metabolism?

Metabolism is a series of chemical processes in each cell that transform the calories we eat into fuel to keep us alive. These processes sustain life, everyday functioning and include breaking down of food to supply energy and building or repairing our bodies.

CFS and metabolism

Carbohydrate metabolism is a biochemical process responsible for the constant supply of energy to living cells. The most important carbohydrate is glucose. The breakdown (catabolism) and synthesis (anabolism) of carbohydrate molecules are how the body stores and uses energy. This process plays out in three main stages: glycolysis, the Krebs cycle, and the electron transport chain.

In CFS, the body loses its ability to burn carbohydrate sugars the regular way to generate energy. So the cells switch to lower-yielding fuels—such as amino acids and fats—for energy, instead of sugar. This ‘metabolic switch’ leads to the production of lactate, which causes pain when it accumulates in the muscles. This could explain both the shortness of breath in CFS patients, as well as why even mild exercise can be so extremely depleting.

What is metabolic health?

Metabolic health is described as having ideal levels of blood sugar, triglycerides, high-density lipoprotein (HDL) cholesterol, blood pressure and waist circumference, without using medication.

CFS and weight gain

Many of the symptoms of CFS, such as increased fatigue and lowered activity levels, are also present in obesity. This means that obese patients with CFS may not receive the proper diagnosis. What’s more, many CFS symptoms, including sleep problems, extreme fatigue, and metabolic switch, may all be contributing factors in weight gain.

Sleep deprivation, which is one of the primary symptoms of CFS, is directly linked to weight gain and obesity. Studies suggest lack of sleep may significantly impact weight gain through effects on appetite, physical activity, and/or thermoregulation.

Some CFS patients report feeling hungrier than normal. It is still unclear why this happens, but it could be linked to hormonal changes and poor sleep patterns.

And while there is no evidence yet to suggest that the underlying disease process in CFS/ME is related to weight gain as it is in the case of an overactive or underactive thyroid gland, the aforementioned reasons could explain why CFS patients may undergo weight changes.

CFS and blood glucose levels

It is crucial for the body to maintain optimal blood sugar levels. A low blood sugar level means that the energy supply to the tissues and the brain is weakened. Meanwhile, a rise in blood sugar levels damages the arteries, which can lead to strokes and cardiovascular disease in the long run.

Difficulty regulating blood sugar levels is a common symptom of CFS/ME, resulting in low blood sugar levels in some patients and elevated levels in others. According to Dr. Sarah Myhill, MD, a UK-based CFS specialist, chronic hypoglycemia is a major cause of fatigue in CFS patients.

CFS and blood pressure/heart health

Heart rate and blood pressure work in tandem to keep the blood flowing at the right pace irrespective of the position the body is in. One of the most common symptoms of CFS is orthostatic intolerance, where a person feels lightheaded/faint or experiences a rapid increase in heart rate upon standing up from a reclining position. So the balancing act of blood vessel squeeze and heart rate response is impaired in many CFS patients. This makes it very hard to maintain stable blood pressure.

CFS and inflammation

Inflammation is the body’s natural response to facilitate healing. When a problem is detected in the body—be it an invading virus, bacterial infection, or tissue damage—the immune system triggers an inflammatory response to send a message to the blood vessels to begin the process of healing. That’s why a little swelling following an injury is always a good sign indicating that the healing process is in fact taking place.

When inflammation becomes chronic due to a misfiring immune system, what we have is autoimmunity. In autoimmunity, the immune system mistakenly identifies the body as a foreign invader and starts to attack it as if it were a virus. So the inflammatory response is triggered and the cells are mobilised to begin healing. Except in autoimmunity, the immune system creates more of whatever part of the body the immune system has identified as an invader. Thus, it continues to attack and heal in an indefinite cycle.

Studies now reveal what researchers have long believed: that there are several biomarkers of inflammation and sustained immune response in the blood of CFS/ME patients. Some researchers even believe that CFS/ME is a neuroimmune (a condition in which a person’s immune system mistakenly attacks parts of the CNS) or neuroendocrine immune disease.

While inflammation may more or less be a given with CFS/ME, the general consensus is that the causes may vary from one case of CFS/ME to another and that some cases are autoimmune while others are not.

Ways to deal with CFS

1) Diet

There are no major studies on the effects of diet on CFS, but, according to Jose Montoya, MD, professor of medicine and specialist at Stanford’s Chronic Fatigue clinic, diet can potentially impact CFS.

While more research may be needed, the most common symptoms of CFS could offer some cues. These are:

  • Cutting down on caffeine: Since difficulty sleeping and feeling well-rested are two of the primary symptoms of CFS, high amounts of caffeine in the system may not help matters. While the quick energy fix one finds in caffeine can be particularly tempting for someone with CFS, according to Montoya, caffeine can offer a false sense of energy, which could lead patients to overexert themselves.
  • Avoiding inflammatory foods: We’ve already seen the major role inflammation plays in CFS/ME. Montoya recommends experimenting with an anti-inflammatory diet or consuming anti-inflammatory foods such as fish and olive oil.
  • Keeping a food journal: While all health and fitness enthusiasts would benefit from keeping a food journal to track the effects of specific foods on the body, it is particularly recommended for CFS patients. Tracking food and symptoms over a period of time may be invaluable in understanding patterns. And since 35–90% of CFS patients also suffer from irritable bowel syndrome, close attention must be paid to any stomach upsets.

According to the British Dietetic Association (BDA), caution must be exercised when it comes to the barrage of conflicting information and advice on the internet about CFS and food. There is no scientific basis for claims that certain restrictive diets such as Anti-Candida (low sugar/yeast diet), Paleo, or Blood Type diets can help CFS and are therefore not recommended. Restrictive diets can also be more expensive, less healthy (many gluten-free foods pack more fat and sugar, and many non-dairy kinds of milk are lower in protein), and far more limiting when it comes to choice. What the BDA does recommend is a balanced diet that includes a variety of healthy foods from each food group:

Fibre and energy: Including a portion of potatoes, bread, rice, pasta, or wholegrains can help keep energy levels stable.

Vitamins and Minerals: Five or more portions of fruits and vegetables a day are highly recommended.

Protein: Two portions of meat, and eggs. fish or pulses, beans, nuts, and cereals take care of the protein quota for the day.

Calcium: Including good sources of calcium such as milk, yogurt, cheese, and soya-based products is essential for bone health.

Hydration: 5-8 glasses of fluids such as water, tea or juices is the recommended daily fluid intake.

2) Pacing exercise for people with CFS

It is crucial for CFS patients to pace themselves when working out, given their high propensity for post-exertional malaise and the fact that symptoms tend to worsen with more physical activity. Here are some points to keep in mind:

  • Establish a physical activity threshold: The total activity that one is capable of over the course of a week without triggering symptoms, for example. Fitness trackers, pedometers, and heart rate monitors come in handy with the process.
  • Begin small: Working up the level of activity in small increments improves the chances of doing more eventually while keeping symptoms in check.
  • Stick with the plateau: Maintain a manageable level of activity until there is a reserve of energy available and you feel comfortable. The right level of activity is that which can be repeated every day without triggering symptoms.
  • Experiment with exercises: The right exercise is one that works best for the individual in question. Pick from a range of gentle exercise options such as stretching, yoga, tai chi, or lightweight training.
  • Listen to the body: Let it have the final say in what you do and how much of it you do on a given day.

3) Sleep

As we’ve already seen, difficulty sleeping is one of the primary markers of CFS/ME. Chronic sleep deprivation can result in a whole range of symptoms all by itself, but for CFS patients, it can worsen existing symptoms and delay recovery. Eight to nine hours of sleep are recommended for CFS patients. In the case of a planned late night, a short nap during the day could be helpful.


Chronic fatigue syndrome is a debilitating illness that affects multiple body systems and is extremely difficult to diagnose. While there is a long list of symptoms associated with CFS, three primary symptoms are necessary for diagnosis. These are incapacitating fatigue that does not go away with rest, worsening of symptoms with minimal physical activity, and difficulty getting a night of restful sleep. Some of the long-term effects of CFS on the body include a dysfunctional autonomic nervous system, impaired blood sugar, and heart rate response, and the metabolic switch, which impacts carbohydrate metabolism, weight gain, and autoimmunity. There isn’t a cure for CFS, but there are a number of ways to manage symptoms. Observing symptoms closely, maintaining a food and symptom log, arriving at a well-thought-out diet that eliminates caffeine, inflammatory foods and anything else that exacerbates symptoms, and establishing a threshold for physical activity are some crucial first steps to keep symptoms at bay.


  1. Metabolism in chronic fatigue syndrome.
  2. CFS as a robust illness
  3. Symptoms of chronic fatigue syndrome.
  4. Chronic Fatigue Syndrome – Mayo Clinic
  5. Chronic Fatigue Syndrome – Healthline

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