Inclusion Criteria:  age ≥ 50 Knee Pain plus American College of Radiology (ACR) Criteria for Knee Osteoarthritis BMI = 27 ≥ kg/m2  Exclusion Criteria:  Significant co-morbid disease that would threaten safety or impair ability to participate in interventions or testing (Blindness; Type 1 diabetes; Severe coronary artery disease) Not sufficiently overweight or obese, BMI < 27 kg/m2 Not having knee pain Inability to finish 3-month study or unlikely to be compliant (Planning to leave area > 1 month during the next 3 months; Unwilling to change eating or physical activity habits; Unwilling to discontinue pain medication use for 3 days prior to testing visit) Living > 30 minutes from the intervention site Age, age < 50 Other conditions that may prohibit the effective delivery of the intervention (Unable to provide own transportation to exercise center; Unable to read or write)