Inclusion Criteria:

1. All ethnic groups and both genders
2. Age: Lower age limit: 19 years; Upper age limit: 45 years
3. Body-mass Index: Lower BMI limit: 30 kg/m2; Upper BMI limit: 40 kg/m2 and weight stable within +/- 5 pounds in the last 6 months, and currently at maximum non pregnant body weight (+/- 5%)
4. A negative treadmill stress test or subsequent follow up cardiac testing for cardiac ischemia.

Exclusion Criteria:

1. History of cardiovascular disease, including coronary artery disease, congestive heart failure, & unstable angina, or uncontrolled hypertension ( > 140/90 mm Hg)
2. Currently smoking or stopped smoking in the last 12 months
3. Medications affecting weight, energy intake, or energy expenditure in the last 6 months
4. Use of oral steroids within the last 12 months
5. History of stroke or seizures, thyroid disease, type 1 or 2 diabetes, Cushings syndrome, cerebrovascular, renal disease, hepatic disease, arrhythmias
6. Cancer requiring treatment in the past 5 years, with the exception of skin cancers other than melanoma
7. Infectious diseases: Self-reported HIV positivity or Active tuberculosis
8. Weight loss or weight gain of > 5% in past 6 months for any reason except post-partum weight loss
9. Likely to move away in next 1.5 years
10. Inability to adhere to the program such as inability to increase walking
11. Currently pregnant, lactating or less than 6 months post-partum
12. Major psychiatric disorder: Exclusions related to medications -Antipsychotic agents (these include, but are not limited to: Haldol, Loxitane, Mellaril, Navane, Prolixin, Stelazine, Thorazine, and Trilafon)
13. Current depression by history or Beck Depression Inventory (BDI)
14. Currently being treated for psychological condition