In this study, we will examine whether a small weight loss in lean, insulin-resistant offspring of type 2 diabetic patients will improve insulin resistance. The control group will consist of subjects matched for gender, age and body weight with no family history of diabetes. Before and after weight loss, rates of basal and insulin stimulated whole body glucose metabolism will be measured using [6,6-2H] glucose during a 3 hour basal period and a 4 hour euglycemic hyperinsulinemic (20 mU/m2-min) clamp. Rates of whole body lipolysis will be determined using [2H5] glycerol, localized rates of lipolysis will be measured using the microdialysis technique and muscle PI 3-kinase activity will be assessed in muscle biopsies. FFA metabolites (fatty acyl CoA, ceramides, diacylglycerol) will be measured in fat tissue collected from the abdominal subcutaneous fat cell depot. Body composition will be determined with bioelectrical impedance and whole body MRI; IMCL will be measured with MRS. Before and after weight loss, insulin secretion will be measured with the hyperglycemic clamp (as described under Day 2 Hyperglycemic Clamp).