Diet-induced weight loss alone or combined with exercise in overweight or obese people with knee osteoarthritis: A systematic review and meta-analysis.

OBJECTIVES: The purposes were to (i) determine the effect of diet-only treatments and combined diet and exercise treatments on pain and physical function and (ii) explore the effect of these treatments on inflammatory biomarkers in overweight and obese adults with knee osteoarthritis.

METHODS: Five electronic databases were searched until March 2017. Randomised controlled trials investigating the effect of non-surgical non-pharmacological weight loss treatment, with or without exercise, on self-reported pain and/or physical function and/or inflammatory biomarkers were selected. Two review authors independently extracted data and assessed risk of bias for each study. Standardised mean differences (SMD) of outcomes were pooled as appropriate, using a random effects approach.

RESULTS: 2676 articles were identified, 19 met review criteria and 9 met criteria for meta-analyses. Diet-only treatments did not reduce pain (SMD -0.13; 95% confidence interval, CI: -0.37, 0.10; I2  = 49%) while a combination of diet and exercise treatments did reduce pain moderately (SMD -0.37; 95%CI: -0.69, -0.04; I2  = 54%). Physical function improved moderately with diet treatments (SMD -0.30; 95%CI: -0.52, -0.08; I2  = 47%) and combined diet and exercise treatments (SMD -0.32; 95%CI: -0.56, -0.08; I2  = 24%). Of the inflammatory markers assessed, only IL-6 reduced with diet-only treatments (SMD -0.23; 95%CI: -0.45, -0.02; I2  = 0%).

CONCLUSION: Overall, moderate pain-relief is achievable with a combination of diet and exercise, but potentially not with diet-only treatments. Findings support that either diet-only treatments or combined diet and exercise treatments moderately improve physical function. Overall, treatment effects on inflammatory biomarkers are questionable.