This study aims to determine the impact of a fiber supplement on body weight and composition in individuals with obesity with specific genetic polymorphisms. It involved 112 adults with obesity, each with at least one minor allele in the FTO, LEP, LEPR, or MC4R polymorphisms. Participants were randomized to receive either a fiber supplement (glucomannan, inulin, and psyllium) or a placebo for 180 days. The experimental group showed significant reductions in body weight (treatment difference: -4.9%; 95% CI: -6.9% to -2.9%; p<0.01) and BMI (treatment difference: -1.4 kg/m2; 95% CI: -1.7 to -1.2; p<0.01) compared to placebo. Further significant decreases in fat mass (treatment difference: -13.0%; 95% CI: -14.4 to -11.7; p<0.01) and visceral fat rating (treatment difference: -1.3; 95% CI: -1.6 to -1.0; p<0.01) were noted. Homozygous minor allele carriers experienced greater decreases in body weight (treatment difference: -3.2%; 95% CI: -4.9% to -1.6%; p<0.01) and BMI (treatment difference: -1.2 kg/m2; 95% CI: -2.0 to -0.4; p<0.01), compared to heterozygous allele carriers. These carriers also had a more significant reduction in fat mass (treatment difference: -9.8%; 95% CI: -10.6 to -9.1; p<0.01) and visceral fat rating (treatment difference: -0.9; 95% CI: -1.3 to -0.5; p<0.01). A high incidence of gastrointestinal events was reported in the experimental group (74.6%), unlike the placebo group, which reported no side effects. Dietary supplementation with glucomannan, inulin, and psyllium effectively promotes weight loss and improves body composition in individuals with obesity, particularly those with specific genetic polymorphisms.

MD (Б-1 077979; University of Russia, 2002), PhD, Professor of Medicine. Present Appointment:​ since 2020 Deputy Director of the Center for New Medical Technologies

1997-1999 Residency of Cardiology, Research Institute of Cardiology, Tomsk

1999-2002 Post-graduate course of Cardiosurgery, Research Institute of Cardiology, Tomsk 2003 Hopital Haut-Leveque, Bordeaux-Pessac, France

2004 St Georg Hospital, Hamburg, Germany

2005 San Raffaele University Hospital, Milan, Italy

2012 Principles and Practice of Clinical Research, Harvard Medical School, USA