INS and obesity due to melanocortin 4 receptor deficiency: Metabolic control in such patients is, however, difficult because the recommended low-fat diet with its high content of carbohydrates usually leads to a vicious cycle: hyperglycemia caused by the high-carbohydrate diet necessitates the use of insulin; efforts to normalise the blood glucose with insulin leads to increase of appetite and bodyweight [3]; the rise of bodyweight exposes the patient to the risk of obesity-associated renal failure [4].