High body mass alters colonic sensory-motor function and transit in humans

There is increased prevalence of abdominal pain and diarrhea and decreased gastric sensation with increased body mass index (BMI). Our hypothesis is that increased BMI is associated with increased colonic motility and sensation. The study aim was to assess effect of BMI on colonic sensory and motor functions and transit. We used a database of colonic tone, compliance, and perception of distensions measured by intracolonic, barostat-controlled balloon, and gastrointestinal transit was measured by validated scintigraphy in healthy obese and nonobese subjects. Regression analysis was applied to assess the association of BMI with colonic sensory and motor functions. We included adjustments for sex differences, age, height, balloon volumes during distension, and psychological stress. Among 165 participants (87 women, 78 men), increased BMI was associated with decreased colonic compliance (P < 0.006, adjusted), decreased pain rating during distensions (P = 0.02, adjusted), and a higher threshold for pain (P = 0.042, adjusted). Sensation for gas, colonic tone, and contraction after meal ingestion were not significantly associated with BMI. Transit was assessed in 72 participants (41 women, 31 men); colonic transit was faster with BMI >30 kg/m² (P = 0.003 unadjusted, P = 0.08 adjusted for gender). In conclusion, BMI >25 kg/m² is associated with decreased colonic compliance and pain sensation; colonic transit is accelerated particularly with BMI >30 kg/m² in women. These data suggest that colonic dysfunction may contribute to diarrhea, but the cause of increased abdominal pain in obesity is not explained by the studies of colonic sensation and requires further study of afferent, spinal, and central mechanisms.