LEP and obesity due to melanocortin 4 receptor deficiency: For example, we and others [5,6,38,39] have shown that maternal obesity is associated with changes in human milk macronutrients (e.g., lipids and proteins) and obesity-related bioactive components (insulin [38], leptin [6], and c-reactive protein [39]) over the course of lactation that are related to infant growth and body composition.