Impact of Fitness, Fatness and the Obesity Paradox Examined

Obesity adversely affects cardiovascular hemodynamics, structure and function, and increases the prevalence of nearly all cardiovascular diseases. At the same time, emerging epidemiological data show a positive association between mild obesity and overall survival. Survival is even stronger in populations that are overweight or that weigh more than normal but less than obese. A state-of-the-art review of the data supporting this "obesity paradox" published Feb. 12 in the Journal of the American College of Cardiology, and suggests that improved fitness, not excessive weight, is largely responsible for better survival.

Additional Resources
  • 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults
  • Obesity Guideline Infographic
  • Insulin Status and Vascular Responses to Weight Loss in Obesity (JACC)
  • CardioSmart for Your Patients: Physical Activity Challenge
  • The authors reviewed the current data surrounding weight, cardiovascular functioning and survival of obesity. They found that obesity, defined as a body mass index (BMI) of 30 or higher, is associated with significantly increased mortality compared with normal a BMI of 18.5 to 25. Optimal survival is seen in those who are overweight, BMI of 25-30, with a statistically significant 6 percent reduction in overall mortality. Mild obesity, BMI of 30-35, is associated with a 5 percent reduction in overall mortality compared to normal BMI, but the reduction is not statistically significant.

    The authors note that obesity worsens most known cardiovascular risk factors, including plasma lipids, blood pressure, glucose and inflammation. Excessive weight negatively affects ventricular structure as well as both diastolic and systolic ventricular function. The conundrum is that while obesity is associated with an increased prevalence of most cardiovascular diseases, substantial data show that obese patients generally have better short-term and long-term prognosis than lean patients with similar cardiovascular disease.

    At the same time, mounting evidence shows that fitness is highly predictive of survival and largely negates the adverse effects of body fatness. In most cardiovascular disorders, patients with high fitness have lower mortality than do individuals without those cardiovascular disorders but with low levels of fitness, according to the authors. Moving forward, the authors note that the data suggest that maintaining or improving fitness is more important than preventing increased adiposity with regards to long-term health outcomes.

    "This obesity paradox seems largely apparent in patients with low fitness, whereas those with better fitness have a good prognosis and no clear obesity paradox is apparent," said lead author Carl Lavie MD, FACC, Ochsner Clinical School-University of Queensland School of Medicine, New Orleans. He adds that they found that "purposeful weight reduction, and especially incorporating exercise training and improvements in fitness, seems to be beneficial."

    Keywords: Prevalence, Prognosis, Body Mass Index, Exercise, Ventricular Function, Risk Factors, Blood Pressure, Obesity

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