Safety and Efficacy of Glucomannan for Weight Loss in Overweight and Moderately Obese Adults

<jats:p><jats:italic>Background</jats:italic>. Few safe and effective dietary supplements are available to promote weight loss. We evaluated the safety and efficacy of glucomannan, a water-soluble fiber supplement, for achieving weight loss in overweight and moderately obese individuals consuming self-selected diets.<jats:italic>Methods</jats:italic>. Participants were randomly assigned to take 1.33 grams of glucomannan or identically looking placebo capsules with 236.6 mL (8 ounces) of water one hour before breakfast, lunch, and dinner for 8 weeks. The primary efficacy outcome was change in body weight after 8 weeks. Other efficacy outcomes were changes in body composition, hunger/fullness, and lipid and glucose concentrations. Safety outcomes included gastrointestinal symptoms/tolerance and serum liver enzymes and creatinine levels.<jats:italic>Results</jats:italic>. A total of 53 participants (18–65 years of age; BMI 25–35 kg/m<jats:sup>2</jats:sup>) were enrolled and randomized. The two groups did not differ with respect to baseline characteristics and compliance with the study supplement. At 8 weeks, there was no significant difference between the glucomannan and placebo groups in amount of weight loss (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mo>−</mml:mo><mml:mo>.</mml:mo><mml:mn>40</mml:mn><mml:mo>±</mml:mo><mml:mo>.</mml:mo><mml:mn>06</mml:mn></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mo>−</mml:mo><mml:mo>.</mml:mo><mml:mn>43</mml:mn><mml:mo>±</mml:mo><mml:mo>.</mml:mo><mml:mn>07</mml:mn></mml:math>, resp.) or other efficacy outcomes or in any of the safety outcomes.<jats:italic>Conclusions</jats:italic>. Glucomannan supplements administered over 8 weeks were well tolerated but did not promote weight loss or significantly alter body composition, hunger/fullness, or lipid and glucose parameters. This trial is registered with<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://clinicaltrials.gov/show/NCT00613600">NCT00613600</jats:ext-link>.</jats:p>