Last week we talked about the January 16th obesity theme issue of the Journal of the American Medical Association. All the study reports were about obesity surgery but almost all the higher number of editorializing articles were about non-surgery approaches. Last week we focused on the first part of that theme. Today we’ll touch on the second part. The part that, at least so far, isn’t working out as well as surgery.
To wit an editorial about the potential of the ketgenic diet, wherein Dr. David Ludwig uncharacteristically admits that “…the evidence for very-low-carb-diets for weight loss and diabetes management is still preliminary.” Also editorials are on offer about “societal norms of obesity,” the genetics of obesity, counting calories “is the challange,” health warnings and taxes on sugar-sweetened beverages, and health policy politics.
But the one editorial that I found most interesting was the one about the relative importance of fatness versus fitness. (1) Cardiorespiratory fitness (CRF) as measured by maximal treadmill exercise tests and physical activity (PA) as measured by asking people about it, are probably more important when it comes to staying alive than fatness as measured by body mass index (BMI). This is something that is not often considered when we talk about the health risks of overweight and obesity. In fact exercise improves longevity in the case of all risk factors. Besides weight, that includes old age, diet, and smoking.
But it’s complicated. In the first place all the evidence is perforce observational, especially the asking people how much they exercise part. Observational studies are the worst kind of evidence because there are a lot of interactions and details in the life of free range humans that are impossible to account for. Also there are probably hard wired interactions like the fact that overweight people may be genetically less fit. One interaction is not present however, as is well known to readers of my fat science column – exercise, before or after the fact, has little or no influence on weight and shape. This is problematical since people care more about how they look than how long they are going to live.
Still this evidence for whatever it’s worth means that the best advice your doctor can give you is to exercise more. Exercise is dangerous, painful (though not as painful as hunger), and expensive. It is especially expensive in time. But maybe there are ways of combining it with things you have to do anyway, like study and read. All medical treatments, even the ones that don’t work, are dangerous, painful and expensive. Maybe exercise is worth it.
1. Kenedy AB, Lavie CJ, Blair SN. Fitness or fatness which is more important? JAMA. 2018;319:231-2.