BACKGROUND Obesity is a well-established risk factor for cardiovascular disease, diabetes, hyperlipidemia, hypertension, osteoarthritis, and stroke. Stimulants, such as ephedrine and caffeine and their herbal counterparts, have proved effective in facilitating body weight loss, but their use is controversial due to their undesired effects. Other nutraceuticals have shown moderate success in reducing body weight, whereas several other compounds have demonstrated little or no effect. Therefore, a tolerable and effective nutraceutical that can increase energy expenditure and/or decrease caloric intake is desirable for body weight reduction. OBJECTIVE The primary purpose of this study was to assess the tolerability and effectiveness of a novel, stimulant-free, dietary supplement containing glucomannan, chitosan, fenugreek, Gymnema sylvestre, and vitamin C on body weight and fat loss and change in body composition in obese adults. METHODS In this single-center, prospective, randomized, double-blind, placebo-controlled study conducted at the University of Guelph (Guelph, Ontario, Canada), obese adults (aged 20-50 years; body mass index [BMI], ≥30 kg/m(2)) were randomized to the treatment or placebo group. The treatment group received 6 capsules of a dietary supplement containing a proprietary blend of glucomannan, chitosan, fenugreek, G sylvestre, and vitamin C daily for 6 weeks, and the placebo group received 6 capsules of rice flour daily for 6 weeks. Body weight; percentage of body fat; absolute fat mass; lean body mass; BMI; upper abdominal, waist, and hip circumference; and anthropometric measurements were recorded at baseline and at study end. Patients completed daily dietary intake records on days 1 to 3 and days 40 to 42. They also completed weekly activity logs throughout the study. RESULTS Twenty-four subjects (mean [SD] age, 37.0 [8.2] years [range, 21-48years]; mean [SD] BMI, 35.7 [6.2] kg/m(2) [range, 28.9-50.9 kg/m(2)]) were assigned to the treatment group (8 women, 4 men) or the placebo group (9 women,3 men). Two subjects (8.3%; 1 patient [8.3%] from each group) dropped out for personal reasons unrelated to the study. No significant changes in the consumption of total calories; the percentage of calories ingested as carbohydrates, fat, or protein; or activity levels were found in either group throughout the study. Compared with the placebo group, the treatment group lost significantly more body weight (-2.3 kg vs 0.0 kg; P<0.01), percentage of body fat (-1.1% vs 0.2%; P<0.05), and absolute fat mass (-2.0 kg vs 0.2 kg; P<0.001). The treatment group also experienced a significantly greater reduction in upper abdominal circumference (-4.5 cm vs -0.7 cm), waist circumference (-4.1 cm vs 0.1 cm), and hip circumference (-2.9 cm vs 0.6 cm) compared with the placebo group (P<0.05 for all). No significant changes in heart rate or blood pressure were found in either group. Both the treatment and the placebo were well tolerated. CONCLUSIONS Within the context of this study, the novel combination of glucomannan, chitosan, fenugreek, G sylvestre, and vitamin C results in significant body weight and fat loss in obese adults. Disclosure: Derek E. Woodgate, MSc, is president and owner of NxCare Inc., which produces the dietary supplement containing glucomannan, chitosan, fenugreek, Gymnema sylvestre, and vitamin C (trade name Calorie-Care™).