Osteoarthritis (OA) is the most common joint disorder, affecting more than 10% of Canadian adults with symptoms in the hands, knees, hips, back, and neck. In Canada, joint damage from osteoarthritis accounts for over 80% of hip and over 90% of knee replacements. Obesity is recognized as the strongest modifiable risk factor in osteoarthritis. It has been reported that obese women and men have nearly four times and greater than five times, respectively, the risk of knee arthritis compared to their non-obese counterparts. The association between being overweight or obese and increased stress on weight-bearing joints like the knees and hips seem intuitive, but the exact manner in which excess weight influences OA is unclear. However, being overweight has been associated with higher rates of hand OA in some studies. Thus, osteoarthritis is considered an active disease process with joint destruction driven by both biomechanical and pro-inflammatory factors. While effective weight management is a laudable health goal for all, it is especially important for obese patients with knee OA because being only 10 pounds overweight increases the force on the knee by 30 to 60 pounds with each step which exacerbates the OA and elevates the risk for future total knee replacement. In addition to alleviating sheer pain, stiffness and risk of mobility disability, weight loss reduces the risk of vascular events which is reported to be higher in people with OA compared to people without OA. Substantial improvements in physical function in obese patients with OA have been reported with even modest weight loss (≥ 5% of baseline weight). Some researchers have concluded that in elderly persons (mean age 70.5 years), if obese men lost enough weight to fall into the overweight category and men in the overweight category lost enough weight to move into the normal weight category, the risk of developing knee OA would decrease by 21.5%. Similar changes in weight category by women would result in a 33% decrease. Even so, weight loss could potentially result in undesirable reductions in lean muscle and bone mass with the potential to aggravate age-related risk of disability and osteoporotic fractures which compromise quality of life and life expectancy. The objective of this report is to review the evidence for clinical effectiveness of long-term primary care weight management interventions to halt or minimize the progression of osteoarthritis in obese patients.