Prevention of Incident Knee Osteoarthritis by Moderate Weight Loss in Overweight and Obese Females

__Objective:__ This study evaluated the effect of moderate weight loss on the incidence of knee osteoarthritis (OA) in middle-aged overweight and obese women, without clinical and radiologic knee OA at baseline. __Methods:__ A total of 353 women (87%) with followup data available were selected from the Prevention of Knee Osteoarthritis in Overweight Females study, which evaluated the preventive effect of a diet and exercise intervention and of oral glucosamine sulfate on the incidence of knee OA. This was an exploratory proof-of-concept analysis, which compared the incidence of knee OA between women who reached the clinically relevant weight loss target of 5 kg or 5% of body weight after 30 months and those who did not reach this target. __Results:__ The weight loss group showed a significantly lower incidence of knee OA according to the primary outcome measure, which was composed of the American College of Rheumatology criteria (clinical and radiographic), Kellgren/Lawrence grade ≥2, and joint space narrowing ≥1.0 mm (15% versus 20%; odds ratio 0.5, 95% confidence interval 0.3–0.9). Moreover, the weight loss also positively affected several health measures, such as blood glucose level, body fat percentage, and blood pressure. __Conclusion:__ A reduction of ≥5 kg or 5% of body weight over a 30-month period reduces the risk for the onset of radiographic knee OA in middle-aged overweight and obese women. Because of the slow progression of the disease, a longer followup period will be necessary before the number of prevented cases of knee OA by moderate weight loss becomes clinically more relevant