Effect of Carbohydrates and Sugar on Body Fat and Metabolism

Eligibility Details: Inclusion Criteria: - Aged 18 to 50 years - BMI ≥ 27 kg/m2 - Weight ≤ 350 lb - Medical clearance from a primary care provider - Willingness to follow a VLC weight-loss diet - Willingness to reside in a research unit for 3 months and eat/drink only provided study foods and beverages - No major food allergies or aversions - Willingness to obtain seasonal flu shot or provide documentation of flu shot for current flu season (winter/spring cohort only) - Willingness to discuss work options (e.g., remote work) with employer, and make appropriate arrangements prior to the Residential phase. Exclusion Criteria: - Change in body weight ≥ 10% during prior 6 months - Specialized diets (e.g., for medical or religious reasons) - Chronic use of any medication or dietary supplement that could affect study outcomes (e.g., insulin, metformin, thyroxine) - Current smoking (1 cigarette in the last week) - Greater than moderate alcohol consumption (> 14 drinks/wk) or history of binge drinking (≥5 drinks in 1 day within past 6 months) - Physician diagnosis of a major medical illness or eating disorder - History of kidney stones - Laboratory tests: ALT>2x upper limit; abnormal HgA1c; abnormal TSH; abnormal creatinine; abnormal uric acid (using the male upper limit for both sexes) - Failed criminal offender background check or sex offender background check - Use of recreational drugs - Current diagnosis or history of kidney stones, gout, or gall stones; or removal of gall bladder - Exercise restrictions or at high risk for complications during exercise Female-specific exclusion criteria: - Menopausal - Any change in birth control medication during the 3 months prior to enrollment - Pregnancy or lactation during the 12 months prior to enrollment, or intent to become pregnant during study participation