Metabolic Inheritance and the Competition for Calories between Mother and Fetus.

During the prenatal period, maternal and fetal cells compete for calories and nutrients. To ensure the survival of the mother and development of the fetus, the prenatal hormonal milieu alters the competitive environment via metabolic perturbations (e.g., insulin resistance). These perturbations increase maternal caloric consumption and engender increments in both maternal fat mass and the number of calories captured by the fetus. However, a mother's metabolic and behavioral phenotypes (e.g., physical activity levels) and her external environment (e.g., food availability) can asymmetrically impact the competitive milieu, leading to irreversible changes in pre- and post-natal development-as exhibited by stunting and obesity. Therefore, the interaction of maternal metabolism, behavior, and environment impact the competition for calories-which in turn creates a continuum of health trajectories in offspring. In sum, the inheritance of metabolic phenotypes offers a comprehensive and consilient explanation for much of the increase in obesity and T2DM over the past 50 years in human and non-human mammals.