CI, ABSI, RFM, and WHtR, but not BMI, were positively associated with fecal incontinence, suggesting that central fat distribution is more strongly related to FI than overall obesity.
The prevalence of fecal incontinence in the study population was 8.4%.
The Conicity Index (CI) was positively associated with fecal incontinence after full adjustment for confounders.
A Body Shape Index (ABSI) was positively associated with fecal incontinence after full adjustment for confounders.
Relative fat mass (RFM) was positively associated with fecal incontinence after full adjustment for confounders.
Waist-to-height ratio (WHtR) was positively associated with fecal incontinence after full adjustment for confounders.
BMI was not significantly associated with fecal incontinence after full adjustment for confounders.
Subgroup analyses revealed interactions by age, BMI, and chronic diarrhea, though positive associations persisted in most subgroups.
CI and ABSI showed relatively stronger associations with fecal incontinence compared to WHtR, RFM, and BMI as measured by AUC.
This research suggests that where fat is stored in the body matters more than total body weight when it comes to fecal incontinence (the involuntary leakage of stool). Using data from nearly 10,100 American adults surveyed between 2005 and 2010, the study found that about 8.4% of participants experienced fecal incontinence. Measures of fat concentrated around the abdomen — including the Conicity Index, A Body Shape Index, relative fat mass, and waist-to-height ratio — were all linked to a higher likelihood of fecal incontinence. Standard body mass index (BMI), which reflects overall body weight relative to height but does not distinguish where fat is located, showed no significant association. Among the five measures tested, the Conicity Index and A Body Shape Index performed best at distinguishing people with fecal incontinence from those without, though the differences between measures were modest and none were highly accurate predictors on their own. The relationship between each central adiposity measure and fecal incontinence appeared to be linear, meaning risk increased steadily as the measure increased rather than only above a specific threshold. These associations held up across most age groups, weight categories, and health conditions examined. This research suggests that clinicians and researchers interested in fecal incontinence may benefit from measuring central fat distribution rather than relying solely on BMI. However, because all measures showed only modest predictive accuracy, they are not precise enough on their own to identify who will develop fecal incontinence. Future studies are needed to confirm these findings in other populations and to determine whether reducing central adiposity might lower the risk of fecal incontinence.
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Upload Your LabsYe Z, Huang G, Lan X, Huang L, Chen E, Hong Y, et al.. (2026). Associations between five anthropometric indices and fecal incontinence: A cross-sectional study based on the 2005 to 2010 NHANES data.. Medicine. https://doi.org/10.1097/MD.0000000000049139