Obesity Linked to Abnormal Bowel Habits, Independent of Diet

A new study suggests a link between obesity and abnormal bowel habits independent of diet, lifestyle, medical conditions and psychological factors. The findings were published in the journal Alimentary Pharmacology and Therapeutics.

Researchers extracted data from the 2009‐2010 National Health and Nutrition Examination Survey. They included survey responses only if respondents completed the bowel health questionnaire (BHQ), were at least 20 years of age, and did not report history of IBD, celiac disease or colon cancer. The study divided body mass index (BMI) into the following categories: underweight (BMI<18.5); normal weight (BMI between 18.5‐24.9); overweight (BMI between 25.0‐29.9); Obese (BMI between 30‐34.9); and severely obese (BMI>35).

Researchers used logistic regression risk ratios to control for such confounding factors as diet, lifestyle, psychological and medical factors. Subsequently, the results of the study found that respondents who were obese or severely obese were 60% more likely to have experienced chronic diarrhea compared to those with normal bowel habits or constipation.

Explaining the Association

“While several previous studies have pointed to an association between obesity and bowel habits, all lacked data on whether dietary or other factors drive the connection,” said corresponding author Sarah Ballou, PhD, a health psychologist in the Division of Gastroenterology, Hepatology, and Nutrition at BIDMC in a press release. “Our research confirms a positive association between obesity and chronic diarrhea and reveals for the first time that this relationship is not driven by confounding factors such as diet or physical activity level.”

While the study shows the link the association is not caused by confounding factors, questions still remain about what underlying causes for obese people being more likely to suffer from chronic diarrhea than non-obese people. Future research is necessary to elucidate this relationship and determine how physicians should approach treating abnormal bowel habits in this population.

“The treatment of obesity and obesity-related medical conditions requires multidisciplinary management,” said senior author Anthony Lembo, MD, a gastroenterologist in the Division of Gastroenterology, Hepatology, and Nutrition at BIDMC. “Clinicians should be aware of the relationship between obesity and diarrhea, especially considering the potential negative impacts altered bowel habits can have on quality of life.”