Objectives: Changes in body composition and blood chemistries between overweight adult subjects receiving a supplement containing either 3 g of konjac glucomannan/300 mg calcium carbonate or a placebo containing only 300 mg of calcium carbonate were compared as the primary objective. A secondary objective was to compare outcome differences between compliant and partially compliant subjects.
Methods: A total of 83 overweight adults (66 women and 17 men) completed a randomized, double-blind, placebo-controlled protocol in which they received either a glucomannan or placebo supplement for 60 days. Dual-energy x-ray absorptiometry (DEXA) total body scans and a 42-measurement blood test were completed at baseline and 60 days later. Compliance was assessed by rating self-reports of (1) how many tablets were taken, (2) adherence to taking the tablets 30 minutes before eating, and (3) a sum of the ratings for (1) and (2). An anonymous poststudy questionnaire and telephone calls were also completed by 80 (96%) of the participants who were used as the study cohort.
Results: No statistically significant differences were found between the groups on changes from baseline on the DEXA and blood tests. However, when subjects were classified as either compliant or partially compliant using the compliance measures, statistically significant reductions in scale weight, percentage body fat, fat mass, total cholesterol, and low-density lipoprotein (LDL) cholesterol were found in the glucomannan group compared to the placebo group.
Conclusions: This study supports the efficacy glucomannan supplementation to reduce body weight, body fat, and circulating cholesterol levels without the concomitant loss of lean mass and bone density often associated with weight loss. However, these positive outcomes were not observable until corrections for compliance were applied.
Keywords: compliance; fat loss; glucomannan; weight loss.