RESUMEN
PURPOSE: The fat mass and obesity-associated (FTO) gene is involved in energy homeostasis. The A allele of the rs9939609 (SNP; T>A) is associated with obesity and higher food intake, while its effect in energy expenditure remains unclear. The aim of this study is to examine whether FTO rs9939609 is associated with the anthropometric outcomes of a physical exercise program and a dietary intervention. METHODS: We studied two independent samples. The first was composed by children and adolescents in which overweight and obese individuals were submitted to a physical exercise program (n = 136) and normal weight participants served as a control group (n = 172). The second sample was composed by obese women submitted to a hypocaloric dietary intervention (n = 126). RESULTS: Physical exercise and dietary intervention were effective, independently of genotype. We found no association of FTO rs9939609 with obesity in children and adolescents (p = 0.67). The rs9939609 affected the response to dietary intervention in obese women: A allele carriers reduced 2.7 cm less of abdominal circumference (AC) than homozygous TT (p = 0.04), while no effect was observed in response to physical exercise in overweight and obese children and adolescents. CONCLUSIONS: The A allele is associated with a worse outcome in response to the hypocaloric dietary intervention regarding abdominal circumference reduction; the same allele did not show interaction with any anthropometric outcomes in response to the exercise program applied.