Some studies in the last decade or so have suggested that packing on a few extra pounds might actually be a benefit to people with Type 2 diabetes. Dubbed the “obesity paradox” of “reverse epidemiology,” the controversial notion may have provided some people with rationale to not put down the fork. To others, the supporters of the obesity paradox are just crazy, as libraries of research show the perils of being overweight and certainly being obese.
The results of a large study sponsored by the National Institute of Health and the American Diabetes Association were published in Thursday’s New England Journal of Medicine, effectively squashing the proponents of the obesity paradox.
The research combined data from the 8,970 participants in the Nurses’ Health Study and the 2,457 participants in the Health Professionals Follow-up Study. The participants were cardiovascular disease- and cancer-free at the time of diagnosis of Type 2 diabetes. Body Mass Index, a commonly used measure of height and weight, was calculated for the participants shortly before diagnosis.
The researchers dissected the data according to groups: a reference group of BMI between 22.5 and 24.99; those under that level with a BMI between 18 and 22.49; BMI between 25 and 27.49 (often called “overweight”); BMI between 27.5 and 29.99 (often also called “overweight” or “severely overweight”); BMI in the range of 30 and 34.99 (obese) and BMI greater than 35 (severely obese).
Further, because of the large number of study participants, the researchers were able to evaluate the data with regard to many other factors, such as smoking habits and age (65 and over vs. under 65 at time of diagnosis).
The study results showed that 3,083 deaths occurred during a mean period of 15.8 years of follow-up.
Top-line results showed that those in the reference group (people with a BMI between 22.5 and 24.99, considered “normal” or “healthy”) had the lowest risk of death from any cause. For the groups aged under 65 and non-smokers, the risk of death rose in direct relation to BMI. For those in the overweight category, there was an increased risk of early death, although not considered statistically significant, meaning the trend was certainly in that direction as validated by increased risk in heavier participants. Obese participants had a 36-percent chance of premature death and severely obese patients stood a 56-percent greater chance of early death, compared to the reference group.
Being skinny isn’t necessarily the answer either, according to the research. Those with a BMI below 22.5 stood a 29-percent greater chance of earlier death than the reference group.
The results for smokers and those people over 65 years old were a little more cloudy, likely because of the wide number of diseases that smoking contributes to and the fact the elderly people typically have other health conditions that can skew the data.
“We observed a J-shaped association between BMI and mortality among all participants and among those who had ever smoked and a direct linear relationship among those who had never smoked. We found no evidence of lower mortality among patients with diabetes who were overweight or obese at diagnosis, as compared with their normal-weight counterparts, or of an obesity paradox,” the researchers stated in their conclusion.
Understand that not every bit of research that is used to support the obesity paradox directly contradicts that the findings of this study. For example, epidemiologist Katherine Flegal’s analysis in 2005 of data from the National Health and Nutritional Examination Survey showed that those at greatest risk of premature death were the extremely obese or the underweight. The contention comes in with Flegal’s determination of data from that study that people with the lowest mortality risk had a BMI in the range of 25 to 30 (overweight) and that obese people were at no greater risk of premature death than people in the normal range.
If nothing else, maybe the takeaway should be that being extremely heavy or very thin is not healthy.
In my opinion, most people are going to run with the idea that not smoking and trying to maintain a healthy body weight and fitness level is the best policy to try and avoid premature death, no matter how much data pundits professing the power of the obesity paradox can drum up. Hopefully, the researched published today by the NEJM puts the obesity paradox to rest, but I’m sure that it won’t.
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