The association between obesity and the risk of colorectal cancer (CRC) cannot be easily evaluated because CRC itself is associated with a gradual loss of bodyweight. Aberrant crypt foci (ACF) can be classified as dysplastic ACF or non-dysplastic ACF by magnifying colonoscopy, and dysplastic ACF are thought to be a biomarker of CRC. Ninety-four participants who underwent colonoscopy at Yokohama City University Hospital, Japan, were enrolled in the current study. We detected 557 ACF, including 67 dysplastic ACF (12.0%). Univariate regression analysis was conducted to determine correlations between the number of dysplastic ACF and various potential risk factors, including patient age, waist circumference, body mass index, visceral fat area (VFA), and plasma adiponectin level. The results of multiple regression analysis revealed that the number of dysplastic ACF correlated with age (correlation coefficient r=0.212, P=0.0383) and plasma adiponectin level (r=-0.201, P=0.0371), even after adjustments for sex, waist circumference, body mass index, and VFA. Our univariate correlation analysis data showed a significant correlation with the number of dysplastic ACF with VFA (r=0.238, P=0.0209), no correlation with subcutaneous fat area, and an inverse correlation with the plasma level of adiponectin (r=-0.258, P=0.0118). Thus, our results suggest that aging and visceral fat accumulation could correlate moderately with colorectal carcinogenesis. The novelty of our study lies in the finding that visceral fat accumulation and a low plasma adiponectin level may promote colorectal carcinogenesis; therefore, these obesity-related parameters may serve as novel targets for CRC prevention.