The Impact of Glucomannan, Inulin, and Psyllium Supplementation (SolowaysTM) on Weight Loss in Adults with FTO, LEP, LEPR, and MC4R Polymorphisms: A Randomized, Double-Blind, Placebo-Controlled Trial

Randomized, double-blind, placebo-controlled trial in adults with obesity carrying at least one minor allele in FTO, LEP, LEPR, or MC4R. In the active supplement arm, 75 participants were randomized and 71 were analyzed; the intervention was tested alongside a reduced-calorie diet and lifestyle counseling.

Participants in the active group received an oral fiber powder taken three times daily, one bag 30 minutes before breakfast, lunch, and dinner, for 180 days. Each bag contained 1 g glucomannan, 1 g inulin, and 3 g psyllium (5 g total active ingredients) dissolved in water; the placebo matched texture, volume, taste, and energy content.

The fiber supplement produced greater weight loss and better body composition outcomes than placebo, with larger responses in homozygous minor allele carriers. From baseline to day 180, weight change was -7.3% with active treatment versus -2.4% with placebo, and absolute weight loss was -6.5 kg versus -2.2 kg (both p < 0.01); 59.2% reached at least 5% weight loss versus 26.5% with placebo, and 21.1% reached at least 10% versus 8.8% with placebo. BMI fell by -2.2 kg/m2 versus -0.8 kg/m2, fat mass by -19.4% versus -6.4%, and visceral fat rating by -1.9 versus -0.6, all favoring the supplement (p < 0.01). Homozygous minor allele carriers lost more weight than mixed allele carriers (-9.4% versus -5.6%; p < 0.01). The authors concluded that the supplement may support genotype-informed weight management, but gastrointestinal side effects were common in the active group.

The trial was relatively short at 180 days and involved a genetically selected obesity population, which limits generalizability. The active supplement was also given with calorie restriction and counseling, so the isolated contribution of the fiber blend is not fully separable. The report notes a high incidence of mild-to-moderate gastrointestinal side effects, and longer, more diverse studies are needed.