Therefore, the aims of this nutrigenetics study were to evaluate the potential interaction between three candidate SNPs, rs1558902 and rs9939609 in the FTO gene and the rs7903146 variant of the TCF7L2 gene, and macronutrient intake with regard to obesity, body fat and muscle composition. This evidence concerns the gene TCF7L2 and obesity due to melanocortin 4 receptor deficiency.