LEP and obesity due to melanocortin 4 receptor deficiency: Individuals with obesity undergoing both a high-fat (60% kcal) and a low-fat (25% kcal) diet with 25% energy restriction for a study by Varady et al. [74] showed decreases in leptin levels (low-fat, 48% vs. high-fat, 28%) and body weight after 6 weeks.