Diet-induced weight loss, exercise, and chronic inflammation in older, obese adults: a randomized controlled clinical trial

Background: Persistent, low-grade inflammation is an independent predictor of several chronic diseases and all-cause mortality. Objective: The intention of this study was to determine the independent and combined effects of diet-induced weight loss and exercise on markers of chronic inflammation. Design: Three hundred sixteen community-dwelling, older ( greater than or equal to 60 y), overweight or obese [body mass index (in kg/m(2)) greater than or equal to 28], sedentary men and women with radiographic evidence of knee osteoarthritis were randomly assigned to four 18-mo treatments: healthy lifestyle control, diet-induced weight loss, exercise, and diet plus exercise. The exercise intervention consisted of combined weight training and walking for 1 h 3 times/wk. The weight-loss intervention consisted of a weekly session with a registered dietitian to provide education and support for lowering energy intake. Results: The diet-induced weight-loss intervention resulted in significantly greater reductions in concentrations of C-reactive protein (P = 0.01), interleukin 6 (P = 0.009), and soluble tumor necrosis factor alpha receptor 1 (P = 0.007) than did no weight-loss treatment. Changes in soluble tumor necrosis factor alpha receptor 1 but not in C-reactive protein or interleukin 6 correlated with changes in body weight. Exercise training did not have a significant effect on these inflammatory biomarkers, and there was no significant interaction between weight loss and exercise training. Conclusions: These findings provide evidence from a randomized controlled trial that a dietary intervention designed to elicit weight loss reduces overall inflammation in older, obese persons. Additional studies are needed to assess the effects of different modes and intensities of exercise on inflammation.