Thus, this pilot study was conducted to examine the influence of two obesity-associated SNP variants (FTO rs7185735 and MC4R rs476828) and the Mediterranean diet intervention on weight loss and modification of nutrient intake and metabolic parameters in overweight or obese, postmenopausal breast cancer patients receiving adjuvant hormone therapy. The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.