The purpose of this study was to determine whether a natural dietary supplement produced favorable changes in body composition during a 4-week diet- and-exercise program. The active compound contains a patented combination of chromium picolinate, inulin, capsicum, L-phenylalanine, and other lipotropic nutrients. A double-blind, weight-loss intervention design was used. Participants were randomly assigned to either a diet/exercise/supplement group (n = 56) or a diet/exercise/placebo group (n = 67). Caloric intake was reduced to 1500 kcal/d and participants walked for 45 minutes, 5 days a week, to attain between 60% and 80% of predicted maximal heart rate. Analysis of covariance (ANCOVA) showed significant differences (P < .05) between groups in percent body fat, fat mass, and fat-free mass; no significant differences were found (P > .05) in body weight, body mass index, or energy intake. Independent t tests showed no significant differences (P > .05) in diet composition between groups. Results indicate that the addition of a natural dietary supplement during a 4-week diet-and-exercise weight-loss program accelerates the rate of body fat loss and helps maintain fat-free mass (lean tissue), thereby producing favorable changes in body composition.