1. Group A- Lean Adolescents a. Exclusion criteria: The subjects will be excluded if they have: a history of chronic disease (leukemia, asthma, inflammatory bowel disease, cystic fibrosis, juvenile rheumatoid arthritis, etc), allergy to local anesthetics (ELAMAX Cream), evidence or history of chemical abuse, anemia and elevated liver enzymes (AST above 80 U/L and ALT above 110 U/L).