Human milk also contains numerous appetite, growth, and obesity-related hormones, including leptin, Insulin-like Growth Factor-1 (IGF-1), glucose, adiponectin, insulin, obestatin, somatostatin, resistin, and ghrelin; higher concentrations of milk leptin were associated with lower BMIZ (BMI-for-age z score), and insulin was associated with lower infant weight, relative weight, and lean mass.64, 65, 66, 67. Here, IGF1 is linked to obesity due to melanocortin 4 receptor deficiency.