This study will explore factors that affect obesity and obesity-related diseases in both Caucasians and African Americans. By looking at the rate at which the human body burns calories while at rest (resting energy expenditure, or REE) and at the rate at which fat travels through the blood (fatty acid flux), this study will examine the relationship between REE and fatty acid flux, both of which are determinants of obesity. Researchers will compare the test results of Caucasians and African Americans to determine if race has an effect on the relationship between REE and fatty acid flux.