Weighing in on the “obesity paradox”

Here’s an absurd little tidbit for you to chew on: According to a recent meta-analysis, being overweight might help you live longer.

(Yes, researchers actually came up with that. And yes, someone actually paid them to do it.)

These findings appeared in the January 2 edition of the Journal of the American Medical Association (JAMA). And just in time for people to give up their New Year’s resolutions, too.

But you might want to think twice before abandoning yours. Because a closer look at these brainiacs’ research reveals that this conclusion isn’t quite as straightforward as it seems.

The analysis was based on three basic body mass index (BMI) categories, with three extra subcategories for each “grade” of obesity. (As usual, that’s an awful lot of obesity.)

  • Underweight, BMI less than 18.5
  • Normal weight, BMI between 18.5 and 25
  • Overweight, BMI between 25 and 30
  • Obese (Grade 1), BMI between 30 and 35
  • Obese (Grade 2), BMI between 35 and 40
  • Obese (Grade 3), BMI over 40

The researchers reviewed close to 100 published studies of nearly 3 million subjects. All of them investigated the connection between BMI and all-cause mortality risk.

Results showed that obese subjects–in particular, those in grade 2 and grade 3 categories–suffered much higher mortality rates than “normal” BMI subjects. No surprise there.

But results also showed that those subjects who were only slightly obese (namely, those falling under the “grade 1” heading) weren’t at higher risk of all-cause mortality. And, in fact, regular overweight correlated with significantly lower all-cause mortality.

I think you’ll agree that these are interesting findings, indeed.

Of course, there may be some explanations for them that have nothing to do with the actual excess weight. For example, heavier patients might present sooner for medical care and receive more aggressive treatment when they do.

It’s also worth noting that BMI is just one generic way to assess health via weight. And it doesn’t tell you anything about your body composition.

In fact, athletes often have higher BMIs than non-athletic people of the same height. So taking factors like waist circumference and body fat into consideration–something that it seems these studies didn’t do–could very well affect results.

Parsing the “normal” weight range into categories, as the researchers did with obesity, might also yield different results.

Being underweight can be as risky as obesity. And it stands to reason that lumping borderline subjects together with people who have BMIs in the ideal range of 21 to 23 might skew the outcome.

Even so, researchers can’t ignore the protective effect that being overweight or “low-obese” seems to have on chronic conditions like heart disease and diabetes. (A phenomenon known as the so-called “obesity paradox.”)

Obviously, this is something that I rarely discuss. (And frankly, I’m not even sure it really exists.) But I’m certainly open to the idea.

It makes enough sense that a little extra fat could come in handy during times of acute illness. Or that it may have some protective benefits against traumatic injury. It could also convey other effects that we just don’t know about yet.

But does that give you carte blanche to start inhaling Oreos, sitting on the couch all day, and ignoring the numbers on the scale altogether?

No, no, and NO.

This “news” may sound new. But the take-home message is as old as Goldilocks herself. Yes, you can be too fat. And you can be too thin, as well. But being just right is well… just right.

Chances are good your body knows exactly where that sweet spot is. And when you eat the right foods, in the right amounts, and follow its lead, you can’t go wrong.

Lesser Degrees of Excess Weight Do Not Increase Mortality. Medscape.  Jan 01, 2013.