Basal metabolic rate (BMR) measured by indirect calorimetry correlates very closely with energy expenditure predicted on the basis of age, gender, and body composition (Cunningham, 1991) in normal weight and obese healthy subjects and in individuals with genetic forms of obesity affecting leptin-melanocortin signaling (Farooqi et al., 2007; Greenfield et al., 2009). Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.