The Metabolic Response to Reduced Branched-chain Amino Acids in Humans

Inclusion Criteria: 1. Male between the age of 35 - 65 2. BMI between 28 - 35 (mildly obese/overweight) 3. Fasting glucose level of 101 - 125 mg/dL 4. Able and willing to give written informed consent 5. Stable weight (within 5 lbs. for at least 3 months) 6. Not taking (or willing to cease taking) over the counter vitamin/mineral supplements 7. Not planning to begin an exercise or diet program Exclusion Criteria: 1. Female 2. Outside required age range of 35 - 65 3. BMI not within range of 28 - 35 4. Fasting glucose not within range of 101 - 125 mg/dL 5. Use of prescription medications for diabetes or weight-loss 6. Use of and unwillingness to discontinue over the counter supplements (e.g. cinnamon, chromium, protein powders) or weight loss beverage or meal plans (e.g. SlimFast or Jenny Craig). 7. Low baseline albumin or pre-albumin levels (below normal reference range) 8. Significant anemia (Hemoglobin \< 11 g/dL) 9. Known bleeding disorder or platelet dysfunction 10. Already eating a low protein diet (less than 14% total caloric intake from protein), as calculated from food diaries provided by subjects 11. Participating in intensive exercise training program (high to moderate intensity exercise greater than 210 minutes per week) or planning to start new exercise program during study period. 12. Significant co-morbidities (including kidney disease, liver disease, GI disease, cardiovascular disease, respiratory disease, malnutrition, substance abuse, psychiatric disease, or a diagnosed eating disorder). 13. Planned smoking cessation or attempt at smoking cessation during study period 14. Inability to tolerate meal replacement beverages due to palatability 15. Recent weight loss (\> 5 lbs within 3 months). 16. Bariatric surgery, gastric banding or liposuction 17. Current or past (within 1 year) use of illicit drugs 18. Claustrophobia