INS and obesity due to melanocortin 4 receptor deficiency: When excessive weight gain occurs early in life, the bowel permeability and metabolic malleability in early childhood are damaged,24 modifying endocrine interactions and changing the infant’s state of inflammatory and oxidative stress.25 Such biological changes in infancy, including insulin resistance and fat accumulation in a critical growth period, could provide a metabolic profile susceptible to obesity development, explaining the higher risk for later overweight and obesity.26