Pregnancy and the early postnatal period are crucial windows of opportunity for the prevention of metabolic diseases. In the United States, 23% of children are already overweight or obese when entering kindergarten, and maternal obesity is consistently one of the most powerful predictors of pediatric obesity.  Breast milk provides not only the building blocks for somatic development, but also the hormonal signals that contribute to the biopsychological organization of the infant. It is further possible that the composition of maternal milk is a final opportunity for the mother to biologically signal the prevailing nutritional environment to her child, such that metabolic efficiency may be increased in times of starvation or limited in times of excess.