In another study, leptin concentrations in the maternal milk of women with obesity did not impact their neonates’ microbial diversity or compositions, but higher insulin concentrations in the mothers’ milk were correlated with increased taxonomic diversity, particularly for Gammaproteobacteria, and they were inversely correlated with Streptococcaceae [47]. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.