Independent medical expert answers
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Fatigue and constant exhaustion: Why do I always feel tired? Why am I tired all day long? What are the medical causes?

Written by: Dr. Martin Winkler, translated to English by Fawn M. Zarkov.
First version: 22 Jul 2008. Latest version: 03 Dec 2010.


Chronic fatigue: exhaustion, constant fatigue, and illnesses associated with fatigue and exhaustion.


I am a 42-year-old woman suffering from obesity (BMI 45). I feel extremely tired every day, all day long. Do you think that I could be suffering from chronic fatigue syndrome (CFS)? What are possible causes of my constant fatigue?


Medical Conditions that Exclude a Diagnosis of CFS (Chronic Fatigue Syndrome)

Many medical and psychiatric disorders are accompanied by symptoms of fatigue or reduced activity. It is therefore very important to conduct a thorough clinical examination before attributing such symptoms to chronic fatigue syndrome.

Perhaps the most relevant clinical diagnoses that exclude CFS are:

Many psychiatric disorders and/or medical treatments can cause symptoms of fatigue. Fatigue and somnolence are common symptoms of depression, dysthymia and bipolar disorders. Any subtype of schizophrenia or delusional disorders can cause fatigue. The same is true of eating disorders such as anorexia or bulimia nervosa.

It is important that a medical examination be performed to rule out these disorders and conditions before making a diagnosis of CFS.

Symptoms of chronic fatigue (CFS)


A state of chronic fatigue, exhaustion and tiredness during the day that lasts more than six months and that cannot be explained by a physical pathogenic cause.

Symptoms of CFS

It is important to note that exhaustion, tiredness during the day and a lack of energy and productivity are very unspecific symptoms and are very common among patients. Typical accessory symptoms of a fatigue syndrome (i.e., chronic fatigue syndrome) are:

It is common to see depression symptoms and anxiety disorders. Due to the number and non-specific nature of these symptoms, it can be difficult to develop a differential diagnosis.

Some researches have found that a virus, XMRV, is very common in people with chronic tiredness syndrome. Other researchers have found similar results, while several other researchers have not been able to repeat this result. Science has not yet come to a firm conclusion of whether a virus can be a cause of cronic tiredess or not.

Psychological causes of exhaustion and fatigue
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