Young adults (men = 48, women = 50) between the ages of 18 to 30 participated in this cross-sectional study that aimed to investigate the effects of body composition on core muscle function, as well as age and gender differences in core muscle function of young adults. Height, body mass, body mass index (BMI), sum of skin folds and waist circumference were measured. Lengths of time holding the front bridge and side bridge were recorded as the measure of core muscle function. Increased sum of skin folds, body mass and waist circumference were associated with poor core muscle function in men and women (p < 0.05). However, high BMI correlated negatively with men's core muscle function only (p < 0.05). ANOVA analysis revealed that men had significantly better core muscle function than women (p < 0.05).