INS and obesity due to melanocortin 4 receptor deficiency: Among the molecular mechanisms, this review focuses on short-chain fatty acids (SCFAs), bile-salt hydrolase (BSH), metabolic endotoxemia and the endocannabinoid (eCB) system, which are associated with the normalization of adipogenesis and the regulation of insulin secretion, fat accumulation, energy homeostasis, and plasma cholesterol levels, thus resulting in anti-obesity and anti-inflammatory effects, improving glycemic control and modulating serum lipids, as previously stated.