We will perform a randomized, controlled trial, the primary aim of which is to assess the effectiveness of a behavioral-based physical activity program in the prevention and treatment of obesity and related co-morbid conditions in a primary care setting. We hypothesize that the prevention and/or reduction of obesity and related co-morbidities in patients randomized to an individualized education and behavior counseling group will be greater by comparison to those randomized to a group that receives standard care alone.

Inclusion Criteria:

• Men and women between 25 and 65 years of age.
• Sedentary lifestyle (planned physical activity for the purpose of health one day per week or less).
• Abdominally obese (waist circumference greater than 88 and 102 cm for women and men respectively).
• Weight stable (± 2 kg) for 6 months prior to the beginning of the study.
• BMI between 25 and 34.9 kg/m2 (Because a lifestyle-based intervention alone for obesity reduction is ideal for persons with a BMI greater less than 35, and, that 94% of overweight and obese Canadian adults have a BMI between 25 and 34.9 kg/m2, subjects with a BMI 35 or greater will be excluded).

Exclusion Criteria:

• Physical impairment which would make the intervention very difficult, or unsafe according to the patient's physician including history of myocardial infarction, stroke, coronary bypass surgery or angioplasty in the last 6 months; peripheral artery disease, unstable angina or ischemia, uncontrolled or insulin dependent diabetes mellitus.
• Alcohol consumption > 21 drinks per week.
• Plans to move from the area.
• Participating in another research study.
• Clinically judged to be unsuitable for participation or adherence
• Inability or unwillingness to provide informed consent.
• For women, planned pregnancy in the next 3 years.