OBJECTIVE: To elucidate the effect of long-term weight variability on C-reactive protein (CRP) levels. DESIGN: Cross-sectional study of the circulating CRP. SUBJECTS: A total of 637 Japanese men aged 40-49y in 1997. MEASUREMENTS: Serum CRP levels, body mass index in 1997 (current BMI), the slope of weight on age (weight-slope) representing an individual's weight trend of direction and magnitude, and the root mean square error around the slope of weight on age (weight-RMSE) representing the weight fluctuation magnitude, as calculated by a simple linear regression model in which each value of the subject s five actual weights (aged 20, 25, 30y, five years ago, and current) was a dependent variable and the subject's ages independent variables. RESULTS: After adjustment for age and confounders, including smoking and health status, the odds ratios of elevated CRP (≥0.06 mg/dl) were 1.83 (95% CI: 1.25-2.69), 2.63 (1.69-4.11), and 10.31 (2.17-48.98) for upper normal-weight (BMI: 22-<25 kg/m2), overweight (25-<30), and obese (≥30) persons, respectively, compared with lower normal-weight persons (18.5-<22). Adjusting for age, confounders, and current BMI, weight-slope was positively associated with CRP level especially among subjects with BMI≥25 kg/m 2 (trend P<0.01), and weight-RMSE was positively associated with CRP level particularly among subjects with BMI <25 kg/m2 (trend P<0.05). CONCLUSION: Our results suggest a state of low-grade systemic inflammation not only in overweight and obese persons, but also in normal-weight persons with large weight fluctuation, possibly explaining in part the positive association between weight fluctuation and CVD.
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