Evidence check: FTO in the context of weight loss

Evidence for FTO in the context of weight loss is moderate, primarily from GWAS linking FTO variants (e.g., rs9939609) to higher BMI and obesity risk. However, effect sizes are small – risk allele carriers average only about 2–3 kg more body weight. For actual weight loss, findings are mixed: some studies suggest risk carriers benefit more from structured diet or exercise programs, while others show no difference. Clinical relevance for individuals is limited because lifestyle factors (calorie balance, physical activity) dominate genetic influence. An FTO test alone does not provide actionable guidance for weight loss. Evidence is rated 'human-moderate'. Consumers should be aware that such tests are often marketed without robust validation for personalized recommendations.