As we've experienced a huge global upswing in the number of people who are overweight and obese, studies of these folks have been undertaken with regard to health risk relative to BMI. One recent meta-analysis including almost 3 million subjects paradoxically demonstrated that those who fell into the category of overweight, with a BMI of 25 to 30, enjoyed longer life that those who were obese (BMI greater than 30) or those of normal or underweight. The argument was advanced that people with increased BMI but who were metabolically healthy were in fine shape with regard to longevity. Now, as Rick and I discuss on PodMed this week, another meta-analysis published in Annals of Internal Medicine concludes that that's false: people who are overweight and obese die earlier than their leaner counterparts. Let's look at what these investigators did.
Observational studies of the effect of metabolic status in normal weight, overweight and obese people with regard to cardiovascular events and all-cause mortality and the clinical characteristics of what the authors call 'metabolic-BMI phenotypes' were included in this analysis. Over 61,000 individuals were represented and almost 4000 events. There were six categories of subject: metabolically healthy and normal weight, metabolically healthy and overweight, metabolically healthy and obese, metabolically unhealthy and normal weight, metabolically unhealthy and overweight, and metabolically unhealthy and obese. The metabolically unhealthy categorization was based on the presence of metabolic syndrome components as defined by a couple of organizations, and included the usual suspects such as triglyceride, LDL and HDL levels, use of blood pressure lowering medications, waist circumference and the like. Two studies also looked at insulin resistance and inflammatory markers as part of the metabolic assessment.
The study found that when studies of at least 10 years of follow-up were analyzed separately, obese subjects did indeed experience a greater risk of all-cause mortality and cardiovascular events in comparison to the normal weight group. At all levels of weight the metabolically unhealthy subjects were about three times more likely to experience an event or die that those who were metabolically healthy. The authors interpret this to mean that some evaluation of metabolic health should be included in any comprehensive assessment, and that studies must be undertaken for sufficient periods of time to discern differences in outcome.
Rick makes the point in the podcast that the increased mortality risk seen with obesity may be a long term risk, but many short term risks are also seen with increasing body weight, including knee osteoarthritis and back problems, among others. We conclude that busting the myth that fatness may be overcome by fitness is important in supporting weight control goals along with exercise targets for all.
Other topics this week include the chickenpox and shingles vaccines and their impact on adults and treating anemia in heart disease patients, also in Annals, and treating ischemia in folks with coronary artery disease in JAMA Internal Medicine. Until next week, y'all live well.