Dietary Essential Fatty Acid Regulation of Omega-3 HUFA Metabolism; Satiety and Body Composition

• INCLUSION CRITERIA:

Subjects will be overweight, but otherwise healthy, pre-menopausal ambulatory volunteers aged 18 to 50.

To be eligible for this research study, participants must:

• Be between 18 and 50 years of age.
• Have regular menstrual cycles.
• Be willing to use an effective method of birth control such as hormonal contraception, intrauterine device, barrier methods combined with spermicide, or surgical sterilization.
• Have a body mass index of 25 to 35 kg/m(2).
• Be otherwise healthy as determined by history, medical examination and laboratory tests.
• Be able to come to the NIH Clinical Center every weekday for 3 months.
• Be able to understand the consent form, and provide informed written consent.

EXCLUSION CRITERIA

Participants are not eligible for this research study if they:

• Have been pregnant or have breast fed within the last 2 years.
• Work, or have an immediate family member who works, with a study investigator. Immediate family is defined as a spouse, parent, child or sibling, whether biological or legally adopted.
• Are HIV positive.
• Have any current, unstable medical conditions including respiratory insufficiency requiring oxygen therapy; cardiac ischemia; cardiac or hepatic failure; or acute neurological illness as assessed by history and physical exam.
• Have evidence of diseases that may influence metabolism (e.g. overt diabetes mellitus, thyroid disease, cancer)
• Have any current or past history of eating disorders such as binge eating or anorexia nervosa.
• Have had weight loss (bariatric) surgery.
• Have gained or lost more than 3% of your current weight in the past 3 months.
• Exercise strenuously, like running, swimming, or basketball, 4 or more times per week.
• Are planning to begin a strenuous exercise program in the next 4 months.
• Take supplements that contain omega-6 or omega-3 fatty acids (e.g. fish, cod liver, borage, evening primrose oils)
• Have significant dietary limitations (e.g. multiple food allergies/intolerances, vegan diet) or special dietary requirements that are difficult to accommodate with study diets
• Have significant claustrophobia that would preclude study tests.
• Have a history of alcohol or substance abuse or dependence in the past 5 years.
• Drink more than 2 alcoholic beverages per day, on average, or 6 drinks per sitting in the past year. Participants may drink up to one alcoholic beverage per day during the study.
• Used marijuana, amphetamines, cocaine, or heroin even once over the last year. Participants may not use marijuana, amphetamines, cocaine, or heroin during the study.
• Have smoked 2 or more cigarettes per week, on average, over the past year.
• Participants may not use tobacco products during the study.
• Eat fish 3 or more times per week on average.
• Have a known bleeding disorder.
• Take medications or supplements that may interfere with this study by altering energy metabolism, nutrient absorption, or food intake. Regular use of the following compounds warrants exclusion: medications for the management of diabetes (Type 1 or 2), typical and atypical antipsychotics, thyroid medications, glucocorticoids, orlistat, decongestants, anti-histamines, and medications for cardiac conditions (e.g. beta blockers), attention disorders (e.g. amphetamine derivatives), blood lipid disorders (e.g. statins, fibrates), and hypertension (e.g. thiazide diuretics), as well as certain anti-depressants (e.g. tricyclics), and supplements that impact energy metabolism, such as ephedrine.
• Regularly take an anticoagulant medication, such as warfarin or aspirin.
• Have a pacemaker, brain stimulator, or other implanted electrical device, permanent eyeliner, metallic prosthesis (including metal pins and rods, heart valves, and cochlear implants) that would preclude MRI scans.
• Are currently participating in any other clinical research studies that include blood draws or other procedures.
• Have a serum follicle-stimulating hormone (FSH) level greater than 20