Thursday, January 3, 2013

Is obesity really a health issue?

I've long had concerns about how we measure and define overweight and obesity, and what it means for health. The entire reason to wage a "war" on the "epidemic" of obesity is because we want to improve the health of individuals and the population. Many studies have demonstrated previously that being overweight and (in some cases) obese is NOT a risk factor for mortality. Obesity only becomes an issue at levels of "Grade 2 Obesity". However, I've always found it difficult to reconcile the data with the message. These studies--and I've been involved in a few related to child obesity--are difficult to publish, precisely because they go against the paradigm, and when they are, they receive little attention.

Yesterday, a study was published that should have helped bring the matter to a close. In a meta-analysis of 97 studies, representing nearly 3 million people and 270,000 deaths, Flegal and her colleagues demonstrated that being in the overweight category (so, a BMI of 25-30, the lowest of the overweight groups) was associated with lower mortality than being "healthy weight". Grade 1 obesity (BMI 30-35) was associated with no difference in mortality.

This is not an inconsequential finding. Meta-analyses have their own set of critiques, but, at least in my opinion, this one addresses to the extent possible most of them. They appear to have a rigorous a clear protocol for selecting the included studies, and perform the analyses in several different ways (presenting all of the findings). Indeed, Dr. Flegal herself is a well-known obesity researcher at the National Center for Health Statistics and has played an important role in development of obesity-related research. If she has any subconscious bias, I would expect it to be in the direction of demonstrating overweight obesity are bigger problems.

The authors make very little comment on the meaning of these findings. They do, however, note that possible explanations include earlier presentation to health care for heavier patients (meaning more screening for risks), and higher metabolic reserves (a fancy way of saying that when you get cancer or other severe illness and lose a bunch of weight, heavier people can tolerate that better). An accompanying editorial (which, unfortunately, can not be accessed for free) extends the discussion a bit, but discuss whether BMI is a good measure of obesity (in terms of fat tissue) and that, of course, weight alone should not be the only factor a physician considers when estimating a patient's risk.

What no one is willing to come out and say is this: Maybe overweight and (moderate) obesity are just not a big deal? Maybe we defined these "diseases" all wrong, and maybe we're creating problems that don't really exist. Maybe we let social perceptions of what someone "should" look like effect these definitions? Maybe we have been unwilling to consider the possibility that overweight is not a health risk because we are so invested in the paradigm of obesity = really, really bad that we are unwilling, as a field, to step outside that paradigm.

1 comment:

  1. Thank you for bringing this up. I also read that study and would agree to say that overweight is not a big deal. I think that our society has a damaged relationship with fat that needs healing. I also think that it is within us to be disgusted by fat, and for this reason we attack obesity more than it deserves. I wonder why this is? Why do we struggle to find beauty in overweight people? What is it that has shaped that preference? What does obesity represent that causes it to be so abhorred?