It is hypothesized that estrogen deficiency induces a decrease in the rate of fat oxidation which leads to accelerated gain of visceral fat mass and its associated insulin resistance. It is further hypothesized that viscera fat accumulation will be prevented by hormone replacement therapy through restoration of fat oxidation. To test this hypothesis, 100 women in early menopause will be metabolically characterized for substrate oxidation, fat distribution, and insulin sensitivity prior to being randomly assigned to receive either hormone replacement therapy or placebo for 2 years. Metabolic testing will be repeated at 2, 6, 12, 18 and 24 months.
