Although common genetic variants in the fatty acid translocase CD36 have been associated with liking of high-fat foods in African Americans12 and common obesity-associated variants have been associated with diary reports of food choices in a number of studies13, 14, this is to our knowledge one of the first experimental studies to show a direct association between macronutrient preference (other than alcohol) and a specific genetic/molecular mechanism in humans. Here, CD36 is linked to obesity due to melanocortin 4 receptor deficiency.