Inclusion Criteria:

1. 18-55 years of age.
2. Body mass index (BMI) between 25.0-39.9 kg/m2.
3. Access to a computer, Internet access, and will demonstrate proficiency with using the Internet and Web-based software programs. Potential participants will be asked to provide the type of computer they have, the name of their internet service provider, and will have to demonstrate their ability to search the internet during their screening visit.

Exclusion Criteria:

1. Report losing >5% of current body weight in the previous 6 months.
2. Report participating in a research project involving weight loss or physical activity in the previous 6 months.
3. For women, report being pregnant during the previous 6 months, or planning on becoming pregnant over the following 3 months of the intervention. (Pregnancy during initial screening will be based on self-report and will be included on the detailed medical history that is completed by subjects. In addition, this will also be obtained as part of the signed medical clearance from the individual’s personal physician.)
4. Currently being treated for any medical condition that could impact body weight (i.e., diabetes mellitus, cancer, etc.).
5. History of myocardial infarction, or a history of undergoing heart surgery such as bypass or angioplasty.
6. Taking medication that would affect heart rate or blood pressure responses to exercise (e.g., beta blockers).
7. Taking medication that could affect metabolism and/or contribute to a change in body weight (e.g., synthroid).
8. Being treated by a therapist for psychological issues or problems, taking pyschotropic medications, or receiving treatment with psychotropic medications within the previous 6 months.
9. No exclusion criteria shall be based on race, ethnicity, or gender.