LEP and obesity due to melanocortin 4 receptor deficiency: Three days of carbohydrate restriction (from 70 to 35% of energy intake) can decrease leptin concentrations by ~ 1.5 ng mL−1 in postmenopausal women [50], and 4-weeks of ketogenic diet reduce serum leptin concentrations by ~ 1.8 ng mL−1 in men with overweight or obesity compared to an isoenergetic diet containing ~ 50% carbohydrate [51].