ABSTRACT
Adipose tissue was once considered as largely inert, but there is now good evidence that it makes numerous important contributions to body function. Moreover, these influences are modulated by the individual’s level of habitual physical activity and the size of his or her fat stores. Some of the benefits of fat accumulation are largely passive, such as protection against mechanical injury, an increase of thermal insulation, and provision of buoyancy when swimming. However, fat also provides the main source of energy required during periods of prolonged exercise and food shortage. It regulates the individual’s appetite through the secretion of leptin, burns any excess of food intake through “futile” metabolic cycling, generates heat, and provides a basis for acclimation when a person is exposed to a cold environment. It also moderates mood state, and it secretes a wide variety of hormones that are important to metabolism, fertility, and the risk of developing atherosclerosis and diabetes mellitus.
