Background: Obesity has been linked with inflammation which may be involved in the early onset of metabolic syndrome, cardiovascular disease, nonalcoholic steatohepatitis, and even cancer. The objective of this study was to examine the association between body mass index (BMI) and levels of inflammatory biomarkers from men and women participating in the latest National Health and Nutrition Examination Survey (NHANES).
Methods: Serum concentrations of C-reactive protein (CRP) and fibrinogen were reviewed from US participants in the NHANES between 1999 and 2004. Biomarker levels were calculated across the different weight classes where normal weight, overweight, and obesity classes 1, 2 and 3 were defined as BMI of <25.0, 25.0-29.9, 30.0-34.9, 35.0-39.9, and >40.0, respectively.
Results: With increasing overweight and obesity class, there are direct linear increases in both the mean CRP and fibrinogen concentrations. With CRP levels of normal weight individuals as a reference, CRP levels nearly doubled with each increase in overweight and obesity class: +0.11mg/dL (95% CI, 0.06-0.16) for overweight, +0.21mg/dL (95% CI, 0.16-0.27) for obesity class 1, +0.43mg/dL (95% CI, 0.26-0.61) for obesity class 2, and +0.73mg/dL (95% CI, 0.55-0.90) for obesity class 3. In contrast to individuals with BMI<25.0, fibrinogen levels were highest among obesity class 3 with an increase by +93.5mg/dL (95% CI, 72.9-114.1).
Conclusions: Obesity is associated with a chronic inflammatory state which may contribute to the development of many obesity-related comorbidities. Our findings suggest that the optimal weight class to minimize inflammation should be within the normal range with a BMI <25.0. Further research is needed to determine whether weight reduction in obese individuals is associated with a reduction in inflammation.