Early childhood (~3-7 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 obesity risk. 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.