Is the “obesity paradox” really a mystery?

bmi range and obesity paradoxIs there a relationship between an ideal range of body weight, body mass index, muscle mass, fat mass and health & longevity, or is it all a mystery resulting in an “obesity paradox”?

Much of the research looking at obesity and body weight via the body mass index (BMI) is simplistic and therefore prone to misinterpretation. The apparent relationship between BMI and mortality has lead some to conclude there is an “obesity paradox.” My Google+ post on whether the “obesity paradox” would be such a “paradox” if the researchers would look at body composition as opposed to BMI can be found here.
I can’t help but wonder if this “paradox” may lie in the simplistic design of the research investigating the nature of the relationship between BMI and mortality, if any.The research is simplistic in that it is quantitative in its design comparing two variables – BMI and year of death – with BMI being a variable with lots of variability. It simply factors height and weight.Are we not able to move beyond this association at this point? It reminds me of my frustration with many of the “breakfast studies” which simplistically ask, “Did you eat breakfast – yes or no.” And look for correlations with certain medical conditions.There was actually a breakfast study last year in which researchers looked at the food being consumed for breakfast by the type 2 diabetics involved in the study. The research investigating the relationship between BMI and mortality needs to move in this more qualitative direction.

I am not a researcher in the field, but in my opinion the so-called “obesity paradox” is another area of research that is in desperate need of more qualitative analysis. We can start by using a relatively simple body composition assesment. It need not be costly.

The study that came out this past week, spurring me to write this post, was a meta-analysis of 32 studies looking at adults over 65 years of age and their risk of mortality (death) based on their BMI. The researchers found people at the high end of a healthy BMI range 24 – 31 were at lower risk of mortality, and those below 23 were at highest risk. The magic number with the lowest risk for death was 27-28.

muscle mass legs and longevityThere may indeed be some benefit for older people to have a BMI higher than is currently recommended for a younger population. I believe we will have a better answer to that question in time, and I speculate it will show a higher BMI is advantageous when muscle mass is also factored into the equation. There was another recent study published last month suggesting this is the case.

In this study, researchers used a muscle mass index, which is the amount of muscle relative to height. Sure, it would have been nice to include non-lean mass in the equation, but it’s a start. They analyzed data from men 55 years of age and older, and women 65 and older. They found people with the highest levels of muscle mass had a significantly lower risk of death.

As I have written on the past, “People need to pay more attention to acquiring lean muscle mass and spend less time worrying about how many pounds of fat they have to lose. Pursue the growth and development of healthy muscle tissue, and the healthier metabolism that this engenders. The rest will likely fall in place, including reduced body fat.”  And longevity?

Although I am sensing a slight change, the importance of some resistance training for adults is not generally advised by health care professionals. I suspect this is in part due to the principle of primum non nocere – “first, do no harm.”

I dare say most health professionals have never engaged in weight training themselves, and it’s safer to tell a patient, “Walk for exercise.” Health professionals need to step up their game in this area, and learn how to safely encourage some forms of resistance exercise for the health of their patients.

It’s important to note the above studies merely point out correlation, not causation.

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About Robert Creighton

Dr. Creighton is a podiatrist and foot surgeon with over 26 years in podiatric practice treating thousands of patients afflicted with the physiological, physical, and psychological side effects and complications of diabetes and pre-diabetes metabolic syndrome. He believes these disorders present a pressing public health concern that need to be more actively addressed in a multidisciplinary way. Dr. Creighton graduated from what is now the Temple University School of Podiatric Medicine after receiving his undergraduate degree in Biology. He is certified by the American Board of Foot and Ankle Surgery, a member of the American Public Health Association, an American College of Sports Medicine certified personal trainer and a Member of the American Nutrition Association.


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