What to watch with FTO and Sport?

The FTO variant (e.g., rs9939609) is the most replicated genetic risk factor for obesity. However, the effect is small: risk allele carriers have on average a 1.2- to 1.7-fold increased risk of overweight, but the influence of physical activity is well documented. Meta-analyses show that exercise can attenuate the FTO effect – but not eliminate it. The interaction is statistically significant but poorly predictable at the individual level. For athletes, FTO says nothing about training ability or performance. The variant primarily affects appetite regulation and energy homeostasis. Marketing often overstates its importance. A DNA test can provide a clue but does not replace dietary and exercise counseling. Carriers of the risk allele may benefit particularly from structured exercise and a high-protein, high-fiber diet. Evidence level: moderate human studies, no clinical guidelines. Beware of overblown 'personalized' training plans based on single SNPs.