Evidence is accumulating that there are sex differences in energy and substrate metabolism.
The positive or negative consequences of such metabolic differences between men and women
need to be evaluated with respect to health outcomes. The importance of aberrant lipid
metabolism in metabolic diseases such as obesity, diabetes and cardiovascular disease, makes
understanding the distinction between "normal" vs aberrant critical to future treatment and
prevention strategies. Sex differences in the effects of catecholamines on lipid metabolism
and substrate oxidation in non-obese, healthy individuals, have been consistently observed.
In addition, distinct differences in men and women exist in the distribution of body fat,
with men typically having greater central adiposity than women. Accumulation of fat in the
abdomen is associated with an increased risk for metabolic abnormalities such as
hyperlipidemia and insulin resistance. In the current study, therefore, the role of
testosterone in determining the sex differences in catecholamine mediated substrate
metabolism and deposition of dietary fat into upper versus lower body adipose tissue depots
will be addressed.