Tissue Partitioning in Early Childhood

Study Summary

Early childhood (\~4-6 years of age) is an important window for determining body composition trajectory and may be a critical period for the development of tissue partitioning patterns that influence later disease risk, including obesity and type 2 diabetes. As adiposity accelerates during this critical period, deposition/ preservation of fat stores may be sustained at the 'expense' of other tissues; i.e. energy homeostasis may be inherently biased toward fat gain. The type and amount of tissue mass accrued in early childhood has implications for metabolic profile, glucose/insulin homeostasis, hormone profile and resting energy expenditure. The interplay between fat and bone deposition represents a physiologic trait enabling the body to choose between shuttling 'energy' towards accrual of a particular tissue. Plausibly the phenotype underlying obesity and diabetes risk may be determined by the differentiation of cell type (adipocyte, osteocyte, etc.) during this early stage of growth and development. In vitro studies demonstrate transdifferentiation under the influence of specific external stimuli, which can switch phenotypes toward other cell lineages. Further, rodent models have demonstrated that exposure to stimuli (exercise) early in life may prevent excess fat mass accrual in adulthood, even when the stimulus is later removed (animals are no longer exercising). Children's early experiences (engagement in physical activity) may 'environmentally induce' alterations in body composition and predispose individuals to diabetes throughout life (Figure 1). Hypotheses and Specific Aims: Early growth patterns and cell differentiation may induce long term effects on body composition by impacting biological and hormonal axes that regulate childhood body composition. Body composition comprises not only absolute mass, but also aspects of size, shape and location. To that end, the following specific aims will be evaluated: 1. Quantify body composition, adipose tissue distr