Intentional Weight Loss in Overweight and Obese Patients With Knee Osteoarthritis: Is More Better?

OBJECTIVE: To determine the dose response effect of weight loss on clinical and mechanistic outcomes in overweight and obese adults with knee osteoarthritis (OA). METHODS: This is a secondary analysis of the diet-induced weight loss only (D) and diet-induced weight loss plus exercise (D + E) groups in the Intensive Diet and Exercise for Arthritis randomized controlled clinical trial. The 240 participants were overweight and obese older community-dwelling adults with pain and radiographic knee OA. Participants were assigned to 1 of 4 groups according to weight loss achieved over an 18-month period: <5% (<5% group), 5-10% (≥5% group), 10-20% (≥10% group), and >20% (≥20% group). RESULTS: There were significant dose responses to weight loss for pain (P = 0.01), function (P = 0.0006), 6-minute walk distance (P < 0.0001), physical (P = 0.0004) and mental (P = 0.03) health-related quality of life (HRQoL), knee joint compressive force (P < 0.0001), and interleukin-6 (P = 0.002). Greater weight loss resulted in superior clinical and mechanstic outcomes, with the highest weight loss group (≥20% group) distinguishing itself on all measures compared with the <5% and ≥5% groups; the ≥20% group had 25% less pain and better function compared with the ≥10% group and significantly (P = 0.006) better physical HRQoL. CONCLUSION: Long-term weight loss of 10-19.9% of baseline body weight has substantial clinical and mechanistic benefits compared with less weight loss. The value of an additional 10% weight loss includes significantly improved physical HRQoL and a clinically important reduction of pain and improvement in function.