Obesity is largely heritable and known to be polygenic.7,8 Numerous metabolic pathways contribute to weight gain, and more than a thousand independent genetic variants have been associated with obesity.7 Against the long belief that genetic predisposition to obesity is non-modifiable,9 increasing evidence from gene-environment (G×E) interaction studies advocates that certain lifestyle factors, such as physical activity, may attenuate the effect of some obesity-related genes.7,10 However, such investigations have been limited to a few lifestyle factors and obesogenic genes such as FTO. The gene discussed is FTO; the disease is obesity due to melanocortin 4 receptor deficiency.