Participants will arrive at the Advanced Imaging Research Center (AIRC) at approximately 8:30 AM. During the morning, participants will have measurements of liver fat in the 3 Tesla (3T) Magnetic Resonance (MR) scanner and measurement of their respiratory quotient (RQ) using an indirect calorimeter. Immediately following the scan, two intravenous catheters will be placed in preparation for the insulin/clamp study: an antecubital vein catheter to infuse dextrose and insulin and a dorsal hand vein catheter for blood sampling. The hand will be kept in a hot box at 70 °C for arterialization of venous blood. Three 10 ml. blood draws will be obtained for the baseline glucose level measurement, insulin infusate preparation, and blood chemistry analysis. At approximately 11:30 A.M., a primed continuous infusion of regular human insulin will be started for the duration of 2 hours. A 20% dextrose infusion will be started after 4 minutes of insulin infusion and adjusted to maintain euglycemia. A small amount of blood (1 ml.) will be drawn every 5 minutes for 2 hours to monitor plasma glucose concentration. The total amount of blood required for the whole procedure is approximately 80 mls. A urine specimen will be collected for determination of urinary glucose losses in the post-absorptive state. Approximately 3 healthy volunteers will have an additional measurement of liver fat after the insulin clamp to determine if changes are evident from the test. The participant will then be given a meal and discharged from the AIRC. The duration of this visit is approximately 7 hours.