Safety and efficacy of glucomannan for weight loss in overweight and moderately obese adults

J Obes. 2013:2013:610908. doi: 10.1155/2013/610908. Epub 2013 Dec 30.


Background: 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.

Methods: 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.

Results: A total of 53 participants (18-65 years of age; BMI 25-35 kg/m²) 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 (-.40 ± .06 and -.43 ± .07, resp.) or other efficacy outcomes or in any of the safety outcomes.

Conclusions: 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 NCT00613600.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Body Composition
  • Body Mass Index
  • Cathartics / administration & dosage
  • Cathartics / therapeutic use*
  • Dietary Supplements
  • Female
  • Humans
  • Male
  • Mannans / administration & dosage
  • Mannans / therapeutic use*
  • Middle Aged
  • Obesity / drug therapy*
  • Obesity / prevention & control
  • Treatment Failure
  • Weight Loss / drug effects*


  • Cathartics
  • Mannans
  • (1-6)-alpha-glucomannan

Associated data