It’s Healthier to be Overweight? My Take on the Recent JAMA Obesity & Longevity/Quality of Life Study

This month, the Journal of the Amercian Medical Association (JAMA) published a meta-analysis (a unifying study of multiple studies) looking at the relationship between Body Mass Index (BMI) and long-term health outcomes.  Not surprisingly, the study demonstrated that those at the extremes of weight, i.e. the extremely thin or extremely obese, are most likely to have poorer qualities of life and die at an earlier-than-average age.  But interestingly, among those with normal weight and those who were slightly-moderately overweight, a surprising finding emerged.  The overweight group had better quality of life and longevity outcomes than those who were considered normal weight. As a result of these studies, many are concluding that our medical systems have been missing the boat with so-called obesity management, and that perhaps those of us who have normal weights could stand to gain 20-30 pounds if we want to live longer healthier lives.

In my opinion, it probably is not reasonable to conclude from this paper that being overweight is healthy. It is much more likely that the problem is in the way that we measure obesity.  The data collected in these studies relied on BMI as an estimate for body composition.  BMI is actually a very poor estimate of body composition/obesity, and is even worse as a proxy for future health. As Christian Nordqvist put it: “If BMI were the only calculation [available], the whole of the English national rugby team would be classed as very-overweight to obese and at high risk of cardiovascular disease.”

If the data collected is unreliable, then so is the conclusion.  It’s the old ‘garbage in garbage out’ cliche.  What this study has done best is to demonstrate, once and for all, that we should stop using BMI as an estimate of future health. Dr. Arya Sharma, founder and Scientific Director of the Canadian Obesity Network, very cogently makes this point here.

The bottom line: If you are sedentary, stressed and eating too many crappy foods, you are leading an unhealthy lifestyle and you may very well be headed for diabetes, heart disease, and a shorter, poorer quality of life.  If you are eating healthfully, exercising regularly, and managing stress effectively, chances are you are at a healthy weight (regardless of your BMI) and will have a longer and higher quality of life.  Unfortunately, this meta-analysis misses that point.