Most et al. found that weight gain in postpartum women with obesity was a result of increased energy intake rather than decreased energy expenditure or differences in breastfeeding [42]; They further reported that concentrations of appetite-regulating hormones like leptin and cholecystokinin were higher in the women gaining weight compared to the women losing weight postpartum. This evidence concerns the gene CCK and obesity due to melanocortin 4 receptor deficiency.