PTH and obesity due to melanocortin 4 receptor deficiency: In addition, vitamin D can play indirectly: (1) low vitamin D stimulates PTH secretion, while PTH promotes insulin resistance and obesity, by inhibiting lipolysis (95, 96); (2) by its interaction with other hormones, e.g., glucocorticoid, sex hormone and renin-angiotensin-aldosterone system (RAAS) (87, 97); (3) by its negative effects on lipolysis (98); (4) by its influence on the increased osteocalcin and adiponectin (99, 100).