Obesity and functional bowel disorders: are they linked?

Obesity and functional bowel disease (FBD) are affecting a large number of people worldwide. They have psychosocial consequences and associated with considerable healthcare resource use. The purpose of this review was a comprehensive study of the relationship between obesity and FBD, as well as mechanisms to explain this relationship. An analysis of the literature provides strong evidence of a link between obesity and diarrhea, but there is currently insufficient data to speak confidently about the link between obesity and irritable bowel syndrome. Most studies suggest that adult obesity is not associated or negatively associated with constipation. The association of obesity with diarrhea is most convincingly explained through diet, eating behavior, changes in the metabolism of bile acids, accelerated colonic transit, altered intestinal microbiota and associated inflammation and increased intestinal permeability. Medicines taken by patients, as well as non-alcoholic fatty liver disease, can play their own role. Planning and conducting studies, including longitudinal ones, based on valid diagnostic criteria and taking into account the widest possible range of confounders, will allow a deeper study of the problem of comorbidity of obesity and FBD. This will help optimize the treatment of these diseases.