Therefore, the development of obesity would be the result of fat accumulation in the adipose tissue promoted by insulin [401], associated with a decrease in energy expenditure and an increase in calorie intake, in order to compensate for the lack of energy substrates from other tissues, or a supposed “starvation” condition, subverting the positive energy balance from cause to consequence [400, 403]. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.