In my latest book, The Fallacy of The Calorie: Why The Modern Western Diet is Killing Us and How to Stop It, I discuss in detail the dangers of pursuing an oversimplified, quantitative-based approach to food and health. In addition to the calorie, I discuss the inherent flaws of commonly used measures such as the body mass index (BMI). In the book and in numerous articles and interviews I have discussed the phenomenon known as the obesity paradox.
Although the originator of the Quetelet index and Ancel Keys, who re-christened the Quetelet index as the body mass index in the 1970s, warned against it; the BMI is commonly applied to individuals to define underweight, ideal weight, overweight and various grades of obesity. At the population level, various grades of obesity have been associated with the development of various disabilities and diseases; among them diabetes and cardiovascular disease.
However, among those suffering from various disabilities and diseases, for certain conditions the presence of obesity is associated with a reduction in mortality. In other words, in certain situations being overweight or obese puts you at less risk than those in the normal or ideal body weight category. This is known as the “obesity paradox.”
Heart failure (HF) is a condition which has a variety of causes. The end result is a condition in which the heart muscle is severely weakened and has difficulty in pumping adequate amounts of blood throughout the circulation. Heart failure is one of the diseases in which the “obesity paradox” has been shown to exist; obesity is associated with better survival for those diagnosed with HF.
However, one common argument against the “obesity paradox” is something called reverse causality. This hypothesis suggests that those with more advanced or severe forms of the disease lose weight more quickly compared to those with milder cases. This weight loss phenomenon, referred to as cachexia in extreme cases, is apparent in those suffering from advanced forms of cancer and from advanced forms of such diseases as acquired immunodeficiency syndrome (AIDS). Thus this argument suggests that those who maintain or gain weight simply have less severe heart failure than those who rapidly lose weight as a consequence of the disease. The resulting obesity is a result of a less severe form of disease and not at all protective in the first place.
An important new study helps demonstrate that this is not so. This most recent study “examined the relationship of pre-morbid obesity (i.e., prior to incident HF) with mortality following incident HF.” The researchers found that when “the overweight/obese patients develop HF, they have lower mortality compared with HF patients with prior normal BMI. These results suggest that a significant component of the obesity paradox is driven by pre-morbid obesity.” In other words, the study examined the BMI classification prior to and after the diagnosis of heart failure was made. They found that being overweight or obese prior to the diagnosis and not just during the disease conferred a mortality benefit. This finding is an agreement with previous data, but significantly suggests that there is a real protective benefit to carrying a bit more weight; at least for those who suffer from heart failure.
Findings such as this and the existence of the “obesity paradox” should propel us forward with aggressive investigation. Further studies will hopefully incorporate metabolomics, genetics, nutragenomics, diet and dietary interventions. Ultimately, we must strive for a better understanding of the drivers of the relationship between our food and our health and wellness. In the meantime, we must be wary of a siren song that calls all of us towards an arbitrary and impersonal “optimal” BMI. For such paradoxes that we glimpse are the warning signs that not only do such “ideals” not exist, but to follow them is to go down the path of folly.
 (Khalid, et al., 2014)
Khalid, U., Ather, S., Bavishi, C., Chan, W., Loehr, L. R., Wruck, L. M., . . . Deswal, A. (2014). Pre-Morbid Body Mass Index and Mortality After Incident Heart Failure: The ARIC Study. JACC, 64(25):2743-2749.
Wang, T. J. (2014). The Obesity Paradox in Heart Failure: Weighing the Evidence. JACC, 2750-2752.