By doing this study, researchers hope to learn whether a person's motivation for food is different after he or she loses weight, and if imaging techniques such as fMRI can be used to predict whether the person will maintain that weight loss over time.

Inclusion Criteria:

• BMI equal to or greater than 30 kg/m2 or 18 to 24.9
• declaration they do not have plans to move out of the Greater Kansas City area for at least 1 year
• willingness to be randomized
• Individuals undergoing weight loss will have to present written approval from a licensed physician that they are healthy enough to participate in a program of moderate diet restriction and moderate physical activity.

Exclusion Criteria:

• Participation in a research project involving weight loss or PA in the previous 6 months, as these proximal experiences may impact the results of this study.
• Subjects who smoke
• Subjects who use special diets (i.e. vegetarian, Adkins, etc.), use medications that affect metabolism (i.e. thyroid, beta blockers), use medications that affect appetite (i.e. Meridia) or cannot exercise (i.e. walk).
• Exhibit signs of eating disorders, restraint, depression
• Participant has any metabolic disease that would affect energy balance (e.g. diabetes mellitus or hypothyroidism).
• Individuals who report being pregnant during the previous 6 months, are lactating, or planned pregnancy within 12 months
• Individuals who are not weight stable (± 4.5kg) within the previous 3 months or have more than 500 kcal/wk of planned physical activity
• Serious medical risk such as type 1 diabetes, cancer, recent cardiac event (i.e. heart attack, angioplasty, etc.)