Obesity paradox and the heart: which indicator of obesity best describes this complex relationship?

Despite the detrimental effects of obesity on coronary heart disease (CHD) and heart failure, obesity is found to be paradoxically associated with improved survival in secondary care of CHD and heart failure. This 'obesity paradox' is an area of active research, and it might be the result of an inaccurate working definition of obesity, which is traditionally defined in terms of BMI. We reviewed the recent literature on the paradox and examined different anthropomorphic measurements and their association with prognosis in cardiovascular diseases.

In CHD, obesity is associated with improved prognosis when defined by high BMI and body fat, independent of fat-free mass (FFM). High waist circumference seems to be associated with worse prognosis in some studies, but is associated with protection and an obesity paradox in those with poor cardiorespiratory fitness (CRF). In patients with heart failure, BMI, body fat and waist circumference, and possibly FFM, have been associated with improved survival. Despite these findings, intentional weight loss remains protective. In both CHD and heart failure, CRF seems to significantly impact the relationship between adiposity and subsequent prognosis, and an obesity paradox is only present with low CRF.

Body composition, including waist circumference, body fat and FFM have a role in clinical practice. Emphasis should be placed on improving CRF, regardless of weight status. Intentional weight loss, particularly while maintaining FFM, should be encouraged in obese individuals.