Diet, Imaging and Energy Balance Trial (DIET)

Inclusion Criteria: Participants must be 18-50 years old, right handed and have a BMI \> 27 kg/m². They must be willing to follow either of the two diets. Exclusion Criteria: 1. weigh over 300lbs. 2. have uncontrolled hypertension (systolic \>160mm Hg, diastolic \>100mm Hg) 3. have hypotension (systolic \<90 mm Hg, diastolic \<60 mm Hg) 4. have coronary heart disease, or cardiac rhythm disorder 5. cerebrovascular disease or peripheral vascular disease that requires intensive hyperlipidemic therapy 6. other significant co-morbid illnesses such as liver disease (AST or ALT \> 100), kidney disease (serum creatinine \> 1.5), cancer, severe emphysema, severe hypertriglyceridemia (TG\>500) 7. have diabetes (insulin or diet controlled) 8. have a current psychiatric disease 9. have current alcohol abuse (greater than 12 drinks per week) 10. have current drug abuse (or treatment within the last year) 11. use of psychiatric medications (including antidepressants, anti-anxiety agents, anti-psychotics, "muscle relaxants" or any other drug that influences mood, cognition, or neurotransmitter systems, i.e. dopamine, norepinephrine, acetylcholine, serotonin, GABA, and glutamate) 12. have had or have an eating disorder including anorexia nervosa, bulimia nervosa, eating disorder not otherwise specified, binge eating disorder, or any other form of disordered eating 13. have had any bariatric/weight loss surgery 14. be taking any diet pills (prescription or over the counter) 15. have been on any diet in the last 3 months 16. have any restrictive dietary requirements (including: vegetarians, vegans, or any other dietary restraints) 17. have any food allergies 18. be on an exclusively ethnic diet 19. be females who are pregnant, nursing mothers or likely to become pregnant 20. have any major medical condition that would make participation unsafe (e.g., have pacemaker or other metallic implant (including dental, orthopedic, or IUD), uncomfortable (e.g., chronic pain), confound results (e.g., psychiatric condition) 21. be left handed 22. have glaucoma, color blindness 23. be using experimental or investigational drugs 24. or suffering from claustrophobia