Does the MC4R rs17782313 gene polymorphism affect the rate of exercise-induced fat oxidation?

This study investigated the effect of the MC4R rs17782313 (<i>T</i> > <i>C</i>) polymorphism on substrate oxidation and metabolic responses during exercise in healthy sedentary men. Forty-eight participants (aged 20-30 years) underwent genotyping and completed a graded exercise test with respiratory gas analysis to assess oxygen consumption (VO₂), respiratory quotient (RQ), and fat and carbohydrate oxidation rates. Participants were grouped as C-allele carriers (risk allele) and TT homozygotes. Group comparisons were conducted for VO₂, RQ, substrate oxidation rates, and body mass index (BMI). Statistical analysis revealed no significant differences between genotypes in RQ, fat oxidation percentage, or carbohydrate oxidation percentage during moderate-intensity exercise (<i>p</i> > 0.05). However, significant differences were observed in BMI, with C-allele carriers exhibiting higher BMI values compared to TT homozygotes (<i>p</i> < 0.05). These results indicate that while the MC4R rs17782313 variant is associated with increased adiposity, it does not appear to affect acute substrate utilization during exercise. Thus, its contribution to obesity risk may be primarily mediated by behavioral and neuroendocrine mechanisms influencing energy intake rather than impairments in metabolic flexibility.