People with ME/CFS experience a range of gastrointestinal symptoms.

Common gastrointestinal symptoms

  • stomach pain
  • nausea
  • bloating
  • irritable bowel
  • food intolerances
  • abnormal appetite
  • weight change

Some underlying gut problems in ME/CFS

  • irritable bowel syndrome (IBS), characterised by abdominal pain, bloating, and alternating constipation and diarrhoea, affects over 50% of people with ME/CFS
  • leaky gut syndrome (bacteria crossing the mucosal lining and entering the blood stream)
  • delayed gastric emptying (gastroparesis)
  • slow gut motility
  • gut dysbiosis:
    • bacterial flora in the gut are altered and less diverse than in healthy individuals
    • small intestinal bacterial overgrowth (SIBO)
    • fewer anti-inflammatory bacterial species (similar levels to those found in people with Crohn's disease and ulcerative colitis)


Diagnosable conditions should be identified and managed accordingly, for example food intolerances linked to genetic predispositions, such as coeliac disease or lactose intolerance; SIBO; and Crohn's disease/ulcerative colitis.

Research has found malabsorption of nutrients in people with ME/CFS. Nutritional deficiencies should be identified and supplementation may be required.

In some patients, common gastrointestinal symptoms such as nausea, constipation, diarrhoea, may be serious enough to warrant treatment.

Any change in gastrointestinal symptoms should be investigated.


Studies have shown that people with ME/CFS have difficulty converting glucose and fats into energy. Some patients find that they do better on a high protein diet and with carbohydrates that have a low glycaemic index (low GI).

ME/CFS may cause food sensitivities and intolerances to worsen or new ones to appear.

People with ME/CFS may find they develop a low tolerance for alcohol and caffeine.

Dietician's role

A dietician experienced in ME/CFS may be helpful in investigating an individual's special needs, including exploration using an elimination diet. A dietician may recommend a specific diet suited to short-term or long-term needs, such as the low FODMAP diet or Friendly Food diet.

Dietary plans need to take the patient’s capacity for food preparation into account. An occupational therapist may work with the dietician to assist with low-energy strategies for food preparation and ways to accommodate orthostatic intolerance (OI).

For those whose ME/CFS is more severe, diet may need to accommodate swallowing difficulties (dysphagia), by using thickened liquids, nasogastric feeding or percutaneous endoscopic gastrotomy (PEG) feeding.

Last edited: 08 December, 2020