Compare the effects of increased free fatty acid (FFA) availability on insulin sensitivity in men, premenopausal and postmenopausal women. Determine the effects of elevated FFA on accumulation of products of the hexosamine pathway and activity of the rate limiting enzyme of this pathway, the effects of elevated FFA on muscle long chain fatty acyl CoA levels, the relationship between induction of insulin resistance and accumulation of these intermediates in men and women. Determine the effects of elevated FFA levels under basal and insulin stimulated conditions on muscle expression of UCP-2 and UCP-3, whether this induction differs between men, pre and post menopause and whether induction of UCP-2 and UCP-3 by permitting higher rates of FFA oxidation at any given level of APT requirement correlates with accumulation of long chain fatty acyl CoA's.