Study sheds new light on the relationship between obesity and fecal incontinence

Fecal incontinence (FI), an uncontrollable lack of bowel control, significantly impairs the quality of life and mental health of millions of individuals in the United States. The relationship between FI and body mass index (BMI), the standard indicator of obesity, is still unclear, despite the fact that it is thought that obesity affects gut function.
Examining more precise measures of obesity, such as body composition and fat distribution, rather than just BMI, might provide light on the relationship between obesity and FI.

Researchers at Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system, demonstrated that waist circumference-to-height ratio (WHtR), a measure of central obesity, was a stronger predictor of FI than BMI in a cross-sectional analysis of the American population.

Utilizing information gathered from the National Health and Nutrition Examination Survey between 2005 and 2010, the researchers computed WHtR and BMI for over 7500 individuals and evaluated their likelihood of having FI. They discovered that FI affected little more than 9% of the research population and that a greater incidence was only inversely correlated with a higher WHtR and BMI.

The study team discovered that increased WHtR, but not BMI, remained consistently linked with FI after controlling for potentially confounding variables such sociodemographics, metabolic comorbidities, nutrition, and physical activity. Additionally, sex-specific studies showed that there were stronger correlations between FI and WHtR in males.

“We are aware that men are more likely than women to have central adipose tissue distribution,” first author Brent Hiramoto, MD, a senior fellow in the Division of Gastroenterology, Hepatology, and Endoscopy, stated. “These differences based on sex may suggest that central obesity plays a significant role in the pathophysiology of FI.”

“Our results indicate that body mass distribution may influence the risk of bowel incontinence,” said Walter Chan, MD, MPH, senior author from the Division of Gastroenterology, Hepatology, and Endoscopy. “BMI is a useful indicator of obesity, but it cannot determine the distribution of adiposity or differentiate between muscle and fat mass. Increased intra-abdominal pressure, which might impact the anal sphincter or pelvic floor, or greater visceral fat with its accompanying oxidative stress and inflammation are two ways that WHtR may exacerbate FI. To learn more about the causes of FI, further investigation is required.