Visceral Obesity Is a More Important Factor for Colorectal Adenomas than Skeletal Muscle or Body Fat

Simple Summary We aimed to determine which of the various body compositions best reflects the risk of colorectal adenoma. Five body indices, including skeletal muscle index, fat mass index, muscle-to-fat ratio, visceral fat index, and skeletal muscle mass-to-visceral fat area ratio, measured by bioelectrical impedance analysis, reflected the risk of adenoma and high-risk adenoma. Among the various body indices, visceral fat index was the most important index associated with the risk of colorectal adenoma. We suggest that more attention should be paid to visceral fat when predicting the risk of colorectal adenoma. Objective: Although the incidence of colorectal adenomas increases with obesity, the role of various body compositions is still unknown. We aimed to determine which body composition best reflects the risk of colorectal adenomas. Methods: Patients aged 50-75 years who underwent colonoscopy and a bioelectrical impedance analysis (BIA) for a health check-up from 2017 to 2019 were retrospectively enrolled. The skeletal muscle index (SMI), fat mass index (FMI), and visceral fat index (VFI) were obtained using BIA. The muscle-to-fat ratio (MFR) and the skeletal muscle mass to visceral fat area ratio (SVR) were calculated. Results: Among 15,102 patients, 6605 (43.7%) had adenomas. SMI, FMI, MFR, VFI, and SVR were all associated with the risk of adenomas and high-risk adenomas in the age- and sex-adjusted model. When further adjusted for metabolic and lifestyle factors, VFI was the only factor significantly associated with the risk of colorectal adenomas and high-risk adenomas (adenomas: odds ratio (OR) 1.40, 95% confidence interval (CI) 1.22-1.61; high-risk adenomas: OR 1.47, 95% CI 1.16-1.87, for the highest quartile). Conclusion: Among the various body indices, VFI was the most important index associated with the development of colorectal adenoma. More attention should be paid to visceral fat when predicting the risk of colorectal adenomas.