Effect of Knowledge of Personal Metabolic-Trait SNP Genotypes with Tailored Lifestyle Recommendations on Body Weight and Body Composition: A Randomized Controlled Trial

Background/Objectives: Communicating genetic risk has been proposed as a motivational tool for weight control, but evidence remains limited. Methods: We conducted a randomized controlled trial among 53 overweight or obese young adults in South Korea. Participants were randomized to receive either their obesity-related genetic results with tailored lifestyle recommendations (intervention, n = 27) or genetic results limited to beauty traits (control, n = 26). Body weight and body composition were measured at baseline, 6 months, and 18 months. Primary outcome was change in body weight; secondary outcomes included body fat mass, body fat percentage, and skeletal muscle mass. Analyses used general linear and mixed models. Exploratory analyses examined effects among participants carrying ≥2 risk alleles across FTO, MC4R, and BDNF. Results: Overall, body weight and composition changes did not differ significantly between groups at 6 or 18 months. In exploratory subgroup analysis conducted among participants with obesity-related genetic risk, body weight increased in the intervention group (model-adjusted mean change, 2.68 kg; 95% CI, 2.28 to 3.09) but decreased in the control group (model-adjusted mean change, −11.58 kg; 95% CI, −1.99 to −1.18) over 18 months. Among participants with obesity-related genetic risk in the intervention group, those who reported behavior changes after receiving their genetic test results experienced modest weight reductions over 6 months compared with non-changers. Conclusions: Disclosure of obesity-related genetic information with tailored advice did not improve weight outcomes overall, but may benefit a subset of genetically susceptible individuals. Larger trials are warranted.