The Obesity Paradox and Cancer—Letter

In a recent publication, Strulov Shachar and colleagues (1) focused on the obesity paradox in cancer (1). The authors discuss hypothetical explanations and take a step beyond body mass index (BMI) or simple weights alone to present other useful and more specific body composition metrics, such as muscle tissue mass, visceral fat mass, and subcutaneous fat mass (1). They conclude their commentary encouraging further studies to examine body composition beyond BMI and to use other body composition metrics to develop individualized treatments and intervention strategies (1). Increasing evidence suggests that cancer patients with a low normal BMI show worse outcomes than obese patients (1). Among patients affected by cancer, obesity has been associated with improved survival compared with normal-weight patients, implying that obesity has a protective effect termed the “obesity paradox” (1). The paradoxical benefit of obesity has also been described in heart failure patients (2). It has been observed that there is a protective advantage in overweight and obese heart failure patients in comparison with their normal-to-low BMI counterparts (2). Obesity represents a public health concern across the globe that is approaching epidemic proportions in both the developed and the developing world (3). Obesity prevalence has been increasing over the past several decades worldwide while its causes are not precisely defined (3). Evolution by natural selection represents one of the best corroborated theories in the history of science, supported by evidence from developmental biology (4, 5). The theory of evolution by natural selection was first expressed in Darwin's book “On the Origin of Species” in 1859 (4, 5). Darwin's theory of natural selection identifies the process by which organisms change over time as a consequence of changes in heritable physical or behavioral traits that allow an organism to better adapt to its environment to be able to survive and produce offspring (4, 5). Darwin proposed that the adaptations of organisms defined as their apparent design can be explained by natural processes governed by natural laws (4, 5). According to Darwin's theory of natural selection, the design of organisms and their remarkable diversity is the result of the gradual accumulation of spontaneously arisen mutations, sorted out by natural selection and promoted by the reproductive success of individuals with incrementally more adaptive elaborations (4, 5). Taken together, I hypothesize that the obesity paradox might simply account for Darwin's theory of evolution by a paradoxical natural selection in the dynamic evolutionary process that enhances obese people' chances of survival as a result of the worldwide escalating rise of obesity.

See the Response, p. 981