Inclusion Criteria:  Ability to provide informed written consent Age between 18 and 65 years Willingness to consume only food prepared by the CRC for 6 weeks Body mass index between 22 and 28 kg/m2 Weight stable to within 2 kg for 3 months preceding study, and at lifetime maximal weight  Exclusion Criteria:  Diabetes mellitus Renal disease Other chronic medical or psychiatric illness Pregnancy or female subject unwilling to use contraception Use of tobacco products Regular intense exercise (>30 minutes of aerobics, 3x / week) Vegetarian or extreme dietary preferences (< 20% or > 40% fat diet, > 40% protein diet) Use of anabolic steroids, glucocorticoids, or lipid-lowering agents Alcohol consumption >2 drinks / day