PROOF: PROtein OverFeeding Effect on Body Weight

Inclusion Criteria: * Have a BMI of 19-30kg/m2 A cutpoint of 26kg/m2 will be used to allocate treatment across the three diets. See the statistics section for more detail. * Are willing to eat all of the study foods even when full * Are willing to eat only foods provided by Pennington and all of the foods provided * Are willing to live at Pennington for 10-12 weeks possibly without leaving the metabolic unit the entire time * Are willing to avoid exercise while in the inpatient phase of the study * Age 18 - 35 Exclusion Criteria: Participants are ineligible to participate in the study if they… * Smoke * Have Diabetes * Have claustrophobia * Have a Fasting Blood Sugar \>110 * Have a history of cardiovascular disease * Have an average screening blood pressure \>140/90 * Have a history of a major psychiatric, addictive or eating disorder or any psychosocial or scheduling factors that could impede study outcomes * Post obese (self-reported BMI) must never have had a BMI greater than 32 * Exercise more than 2 hours per week * Unable to complete VO2 max test. * Weight gain or loss of \> 3kg in the last 6 months * Have significant renal, hepatic, endocrine, pulmonary or hematological disease, or a history of gout * Have had previous GI surgery, Obstructive disease of the GI tract, Hypermotility disorder or a history of problems of impairment of the gag reflex. * Corticosteroid use in the last 2 Months * You are pregnant or breastfeeding * Have Irregular menstrual cycles * Use Depo-Provera, hormone implant or estrogen replacement therapy * Have an allergy to PABA (a component of a B-vitamin often found in sunscreen)