Discrepancies Between BMI and Classic Cardiovascular Risk Factors

Obesity is related to increased cardiovascular risk. It is unknown whether increasing levels of obesity also increase levels of cardiovascular risk factors and systemic inflammation. This study describes the relationship between classic cardiovascular risk factors and inflammatory markers with BMI in a group of obese and non-obese subjects.

Obese subjects (BMI ≥ 30 kg/m²; n = 576; mean ± SD BMI 43.8 ± 7.58 kg/m²) scheduled for bariatric surgery were included. The reference population consisted of non-obese volunteers (BMI < 30 kg/m²; n = 377, BMI 25.0 ± 2.81 kg/m²). The relationship between BMI quintiles and the levels of cardiovascular risk factors was analyzed. Adipose tissue volumetry was performed in 42 obese subjects using abdominal CT scans.

The obese group included more women and subjects with type 2 diabetes mellitus, hypertension, and current smoking behavior. In obese subjects, HDL-C and triglycerides decreased with increasing BMI. Systolic and diastolic blood pressure, total cholesterol, LDL-C, and apoB were not related to BMI in the obese group, in contrast to the non-obese group. Inflammatory markers CRP, leukocyte count, and serum complement C3 increased with increasing BMI in the obese group, while these relations were less clear in the non-obese group. The subcutaneous adipose tissue surface was positively correlated to BMI, while no correlation was observed between BMI and visceral adipose tissue.

Markers of inflammation are strongest related to BMI in obese subjects, most likely due to increased adipose tissue mass, while cardiovascular risk factors do not seem to deteriorate above a certain BMI level. Limited expansion capacity of visceral adipose tissue may explain these findings.