Is the Obesity Paradox an actual paradox ?
Being a paradox an anomaly, and inconsistency, it would be supposed to occur in very rare occasions. I am, however, amazed how often this so-called paradox manifests itself. This phenomenon was described quite a few years ago (1). Yet, the term “obesity paradox” was coined by Gruberg (2) who found that patients with known coronary artery disease and BMI within the normal range (<25 kg/m2) who undergo percutaneous coronary intervention are at the highest risk for in-hospital complications and for increased one-year mortality. The evidence that being overweight or obese is associated with lower mortality has been demonstrated in individuals with heart failure (3) , established coronary artery disease (4) and in a range of cardiovascular disease (CDV) conditions up till today (5), as well as in several non CDV conditions [Reviewed in (6)]. This paradox is explained by some people stating that a BMI of ∼25–35 kg/m2 benefits patients with chronic disease because excess fat serves as an energy depot in times of need. If you are overweight, the most effective thing you can do to prevent diabetes is to lose weight. Right? . However, in the last twist of this not-quite-paradoxical obesity paradox, three very recent studies might disagree. Based on data from 2625 US individuals with incident diabetes (7), when compared with overweight and obese individuals, those who are normal weight at the time of diabetes incidence have higher mortality rates. Additionally, 89,056 Taiwanese individuals with type 2 diabetes where followed for 12 years (8). In all, 30.3% died during follow-up period. Increased risk of death was associated with older age, longer duration with diabetes, using insulin, male sex, hypertension, smoking and lower BMI. Age, sex and risk adjusted hazard ratios demonstrated reduced risk of all-cause mortality with increasing category of BMI, all the way from underweight, to class II obesity. Likewise, weight loss does not reduce cardiovascular events in people with longstanding type 2 diabetes, according to The Look AHEAD study supported by the National Institutes of Health ( more information in www.lookaheadtrial.org ). All these studies lead to my reflection. My take-home message. There really is no such a thing as obesity. There are many “obesities”. Obesity may (or may not) predispose to developing a number of health problems. Once those problems have developed, some obese patients may have a survival advantage over patients who are not. Obesity comes thence in many different flavors. We, as scientists, must find a way to differentiate those obesities. 1. P. Degoulet et al., Mortality risk factors in patients treated by chronic hemodialysis, Nephron 31, 103–110 (1982). 2. L. Gruberg et al., The impact of obesity on the short-term and long-term outcomes after percutaneous coronary intervention: the obesity paradox?, Journal of the American College of Cardiology 39, 578–84 (2002). 3. A. Oreopoulos et al., Body mass index and mortality in heart failure: a meta-analysis., American heart journal 156, 13 (2008). 4. A. Romero-Corral et al., Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies, The Lancet 368, 666–678 (2006). 5. O. Angerås et al., Evidence for obesity paradox in patients with acute coronary syndromes: a report from the Swedish Coronary Angiography and Angioplasty Registry, European Heart Journal (2012) . 6. P. A. McAuley, S. N. Blair, Obesity paradoxes, Journal of Sports Sciences 29, 773–782 (2011). 7. M. R. Carnethon et al., Association of Weight Status With Mortality in Adults With Incident Diabetes, JAMA 308, 581–590 (2012). 8. C. H. Tseng, Obesity paradox: differential effects on cancer and noncancer mortality in patients with type 2 diabetes mellitus, Atherosclerosis (2012).