Hydroxycitric acid (HCA), the main compound of Garcinia cambogia extract, is a competitive blocker of ATP-citrate-lyase, presenting a potential inhibition of fatty acid biosynthesis. Glucomannan fibers, abundant in Amorphophallus konjac, seem to reduce the absorption kinetics of dietary fat. Therefore, the aim of this double-blind randomized study was to evaluate the pharmacotherapeutic efficacy of standardized extracts of G. cambogia (52.4% HCA) plus A. konjac (94.9% glucomannan) in the treatment of obesity. Fifty-eight obese subjects (BMI 30.0-39.9 kg/m(2)) were assigned to the placebo group (n = 26) or the treatment group (n = 32); no dietary restrictions were applied. Over a 12-week period, subjects were given daily doses of either Garcinia (2.4 g) plus Konjac (1.5 g) or placebo prior to their main meals (3 times/day). Before the start of treatment, and every 4 weeks thereafter, the following were recorded: height, weight, circumferences and body composition, resting energy expenditure (REE), lipid profile and glucose levels. The treatment had no significant effect on anthropometric parameters, REE, triglycerides or glucose levels. However, a significant reduction was observed in total cholesterol (-32.0 +/- 35.1 mg/dL) and LDL-c levels (-28.7 +/- 32.7 mg/dL) in the treated group, the final levels being significantly lower than those of the placebo group (p = 0.008 and p = 0.020, respectively). The results obtained suggest that the treatment had a significant hypocholesterolemic effect, without influencing the anthropometric or calorimetric parameters tested.