To determine if there are sex and race differences in FFA flux and to ensure adequate enrollment of both African American and Caucasians, this investigation is a collaborative effort between the National Institutes of Health (NIH) in Bethesda, Maryland and the Mayo Clinic in Olmsted County, Minnesota. The greater Washington, DC, metropolitan area, where NIH is located, has a large African-American community whereas over 90 percent of residents of Olmsted County are Caucasians. Therefore, sex differences in FFA flux in African Americans will be mainly studied at the National Institutes of Health. Sex differences in FFA flux in Caucasians will be mainly studied at the Mayo Clinic. But, to confirm the ability to combine data from two different sites, some Caucasians will be enrolled at NIH and some African Americans will be enrolled at the Mayo Clinic. The results of the two studies will be combined to determine if there are race differences in FFA flux.