Background: Irritable bowel syndrome (IBS) is a common yet debilitating disorder of gut-brain interaction, characterized by gut-brain axis dysregulation, visceral hypersensitivity, and other comorbidities. Obesity has been hypothesized to be a risk factor linked to IBS, albeit evidence remains conflicting. Given the growing global prevalence of obesity and IBS, we performed a meta-analysis examining their purported association.
Methods: Embase, MEDLINE, and the Cochrane Library were searched to identify studies reporting the prevalence and odds ratios (ORs) of IBS according to BMI categories. Random effects meta-analyses were used for the primary analysis.
Results: From 1713 articles, 27 studies were included. Our findings showed that using study-defined categories for overweight, obese, and normal BMI, the odds of the diagnosis of IBS were not associated with overweight (OR 1.02; 95% CI 0.89 to 1.17; p = 0.772) or obese BMI (OR 1.11; 95% CI 0.91 to 1.37; p = 0.309). The meta-analysis of study-reported adjusted odds ratios of IBS among individuals living with overweight or obesity also did not yield significant results. Further sensitivity analysis by the Rome criteria demonstrated a statistically significant association between obese BMI and IBS in studies using the Rome IV criteria (OR 1.59; 95% CI 1.13 to 2.23; p < 0.01), with significant subgroup difference between studies using the Rome II, Rome III, and Rome IV criteria. Further sensitivity analysis using the different cut-off values and subgroup analysis by geographical territory did not yield significant associations.
Conclusions: In summary, excess body weight may not be a primary driver of IBS risk. Future research should focus on longitudinal studies that account for changes in weight and other lifestyle factors, as well as detailed mechanistic investigations.
Keywords: irritable bowel syndrome; lifestyle; meta-analysis; obesity; overweight; risk factor; systematic review.