‘Fitness vs. fatness’ may help explain obesity paradox in CVD survival
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Cardiorespiratory fitness appears to be more important for CVD and CHD survival than weight or BMI, which may explain the existence of the obesity paradox, a speaker reported.
In his presentation at the virtual Cardiometabolic Health Congress, Carl J. Lavie, MD, FACC, FACP, FCCP, professor of medicine, medical director of cardiac rehabilitation and preventive cardiology and director of the exercise laboratories at the John Ochsner Heart and Vascular Institute at the University of Queensland School of Medicine in New Orleans, discussed the hypothesized association between obesity, physical activity and reduced CV mortality risk in people with obesity.
“Both fitness and fatness are important, and in a perfect world, everyone would remain lean and fit throughout their life span, from childhood to old age,” Lavie said in a presentation. “If that occurred, we would limit cardiovascular disease and cardiovascular disease mortality, considerably. But this is hardly the case in our present society where most gain weight and lose fitness. It would be better to gain some weight and maintain fitness than vice versa because the majority of the evidence suggests that fitness is considerably more important than fatness for long-term health.”
According to a 2009 analysis published in the Journal of the American College of Cardiology, approximately 75% of adults in the U.S. are overweight or obese, and obesity is the second most prevalent cause of preventable death, behind tobacco use.
Obesity is associated with increased risk for insulin resistance, hypertension, abnormal left ventricular geometry, dyslipidemia, worse endothelial function, HF, atrial fibrillation, obstructive sleep apnea and more.
“There is overwhelming evidence that supports the importance of obesity in the pathogenesis and progression of most cardiovascular disease and especially heart failure. But we now know an obesity paradox does exist,” Lavie said during the presentation. “At present, there is little evidence supporting purposeful weight reduction, but substantial evidence supporting increasing physical activity and exercise training, especially when it increases cardiorespiratory fitness in patients with cardiovascular disease. Most of this evidence is not in very severe obesity. There is hardly anything that would suggest that having very severe obesity is beneficial over the term, even for patients with cardiovascular disease.”
Although obesity may confer higher risk for developing CVD, the obesity paradox may explain the surprisingly lower incidence of CVD mortality among patients with overweight, according to the presentation.
A study published in The New England Journal of Medicine evaluating the association between BMI and HF prevalence found that men and women with overweight or obesity experienced a significantly greater risk for HF compared with individuals with a normal BMI. However, another analysis, published in JACC, showed that those who had overweight or obesity before HF had improved cumulative survival compared with patients with HF and normal BMI.
“The reasons for this are not all clear. We know that advanced heart failure is a catabolic state. ... This may have something to do with very severe heart failure. We know that adipose tissue produces tumor necrosis factor (TNF) alpha receptors that may neutralize TNF alpha,” Lavie said during the presentation. “Obese patients have lower atrial natriuretic peptides and lower plasma renin activity, which may cause the obese to present earlier with less severe disease. We know [patients with obesity] have higher blood pressure, so maybe they can tolerate more of the cardioprotective medicines that we now use for heart failure. Again, the reason is not totally clear.”
Another investigation conducted by Lavie and colleagues, published in JACC, evaluated the relationship between body fat, lean mass and CHD mortality. Lavie and colleagues found that patients with high body fat and/or high lean mass had better 3-year mortality compared with those with low body fat and low lean mass.
Lavie added that cardiorespiratory fitness in patients with overweight and obesity may contribute more to the prevention of CVD and CHD mortality than weight alone.
According to a study published in Mayo Clinic Proceedings in 2012, individuals with high levels of cardiorespiratory fitness and overweight (HR = 0.94; 95% CI, 0.69-1.3) or obesity (HR = 0.53; 0.21-1.31) had significantly lower risk for mortality in CVD or CHD.
Moreover, the same analysis demonstrated that overweight (HR = 1.46; 95% CI, 1.07-2) and obesity (HR = 1.93; 95% CI, 1.34-2.79) was less protective among those with low levels of fitness compared with patients with normal BMI.
Researchers observed similar results when individuals were stratified by waist circumference.
References:
- Horwich TB, et al. J Am Coll Cardiol. 2001;doi:10.1016/S0735-1097(01)01448-6.
- Kenchaiah S, et al. N Engl J Med. 2002;doi:10.1056/NEJMoa020245.
- Lavie CJ, et al. J Am Coll Cardiol. 2009;doi:10.1016/j.jacc.2008.12.068.
- Lavie CJ, et al. J Am Coll Cardiol. 2012;doi:10.1016/j.jacc.2012.05.037.
- McCauley PA, et al. Mayo Clin Proc. 2012;doi:10.1016/j.mayocp.2012.01.013.
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Lavie CJ. Obesity & lifestyle. Presented at: Cardiometabolic Health Congress; Oct. 21-24, 2020 (virtual meeting).
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