Research Round Up Part 3: Weight, Shape, and Mortality

So, you’re with me thus far: Diets don’t work to help people lose weight. “Healthy lifestyle change” doesn’t help people lose weight (nor is it clear that it helps people get healthy, actually, but more on that later). Your failure to feel better by changing your body shape or size may be beginning to make sense in context: You can’t do it, because apparently it can’t be done.

But what about your health? No less an authority than the Centers for Disease Control is standing ready to persuade you that obesity is a terrible public health epidemic. One would think that getting or staying thin must be a prerequisite to a long, healthy life.

Let’s look at that idea a bit more closely. To do that, we start with your BMI, your Body Mass Index. The BMI is a measure of body size that is less crude than a simple weight measurement in that it corrects for expected variation in weight due to height. (I said it was less crude. I did not say it was elegant.) Research done on obesity often uses BMI as its outcome measure.

Here, let’s calculate your BMI.

Mine comes out at about 27, which puts me in the “overweight” category. If you run the widget, you’ll see it places you into one of four categories.

  • underweight (BMI < 18.5)
  • normal weight (BMI 18.5-24.9)
  • overweight (BMI 25-29.9)
  • obese (BMI >= 30)

Researchers usually also distinguish between

  • mildly obese (BMI 30-34.9) and
  • moderately/extremely obese (BMI >= 35)

Click here to see if you can put these categories in order by risk of mortality. Which category has the highest mortality risk? Which has the lowest?

Are you surprised by the correct answers? All of the large, epidemiological studies of which I am aware on this topic have ALL come up with this same rank ordering of mortality risk.

So if “longevity “is a decent proxy for “better health,” then the fabulous “mildly obese” Kate Harding

is “healthier” and can expect to live longer than the apparently “normal-weight” Beyonce:

And the “moderately/extremely obese” fashion icon Lesley Kinzel

is in better health and can expect to outlive apparently”underweight” Angelina Jolie:

A quick note: In looking at these photos, I encourage you to check your body policing urges at the door. I am not claiming that any of these prominent women is or is not healthy, or does or does not lead a “healthy lifestyle” (whatever that means), as I don’t have any data to address those questions and am not inclined to police the private, personal behavior of individuals even if I did. I set these pictures side-by-side as vivid illustrations to encourage you to challenge your stereotypes about body shape and health and marvel about the inaccuracy of the messages you might have received about that. They’re not here so you can trade one set of unrealistic expectation about what is “healthy” for another.

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