It’s as if a switch has been flicked. Evidence is mounting that chronic fatigue syndrome (CFS) is caused by the body swapping to less efficient ways of generating energy.
Also known as ME or myalgic encephalomyelitis, CFS affects some 250,000 people in the UK. The main symptom is persistent physical and mental exhaustion that doesn’t improve with sleep or rest. It often begins after a mild infection, but its causes are unknown. Some have argued that CFS is a psychological condition, and that it is best treated through strategies like cognitive behavioural therapy.
But several lines of investigation are now suggesting that the profound and painful lack of energy seen in the condition could in many cases be due to people losing their ability to burn carbohydrate sugars in the normal way to generate cellular energy.
Instead, the cells of people with CFS stop making as much energy from sugar as usual, and start relying more on lower-yielding fuels, such as amino acids and fats. This kind of metabolic switch produces lactate, which can cause pain when it accumulates in muscles.
Together, this would explain both the shortness of energy, and why even mild exercise can be exhausting and painful.