Additionally, the administration of FGF21 to obese and diabetic mice reduces body weight, whole-body fat mass and liver triglyceride content, increases fat utilization and energy expenditure, and improves glucose tolerance and insulin sensitivity in the liver and adipose tissue14–19, placing FGF21 as a therapeutic potential for treating obesity and diabetes. This evidence concerns the gene FGF21 and obesity due to melanocortin 4 receptor deficiency.