Cross Fitness

Study Versus Headlines on Fatness and Fitness

The headlines say the benefits of exercise can outweigh the health effects of severe obesity. The study says no such thing. The study examined fitness, not exercise. It showed that fitness might benefit even people with severe obesity, not that it cancels out obesity’s risks. But what will most people remember? The headline.

A new study from the Wharton Medical Clinic in Canada lost to sensational headlines this week, thanks to a sloppy press release from York University.

Associations Between Fitness, BMI, and Health Risks

This was an interesting study, even though it was observational – not a real experiment to test the effects of exercise. Kathy Do and colleagues examined data from 853 patients at a single point in time. The patients completed a treadmill test to assess their fitness levels – high or low. Based on BMI, investigators sorted these obesity clinic patients into three groups: mild, moderate, or severe obesity.

What they found was that very fit people were healthier than people who weren’t as fit at every level of obesity. In fact, the differences were even stronger for people with severe obesity. But even so, it was the degree of obesity that determined most of the metabolic health risk of patients in this study. Not fitness.

And waist circumference did a better job of accounting for that fact than BMI did. At any given BMI, waist circumference tended to be smaller if fitness was higher.

No Exercise Behaviors, No Cause and Effect

This study was a snapshot of correlations, not a study of the effects of exercise. In fact, researchers didn’t collect any data on how much or how little people exercised. They only looked at metabolic health risks, fitness levels, and obesity.

It’s a good study, providing good insight on the potential for benefits from staying fit – even if a person has severe obesity. Too bad that a sloppy press release hides that insight.

Click here for the study and here for the press release. For a slightly more enlightened perspective from the LA Times, click here.

Cross Fitness, photograph © brisabarcelona / flickr

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February 14, 2018

3 Responses to “Study Versus Headlines on Fatness and Fitness”

  1. February 14, 2018 at 10:51 am, Angela Meadows said:

    While I loathe the appalling reporting of obesity science as much as the next person, I can’t help but notice the irony in that it usually goes the other way – “fat and fit is a myth” on every study on MHO that has studied neither fitness nor exercise.

  2. February 14, 2018 at 12:41 pm, Ted said:

    Thanks Angela! Your point is an important one.

    I trip over irony everywhere I turn.

  3. February 14, 2018 at 1:32 pm, John DiTraglia said:

    Fitness is to some extent genetic. Still it can be improved by exercise. Fitness is a very difficult to measure variable in the correlation of BMI with longevity and risk factors.
    It is most probably a good idea to exercise and though it won’t change your wt or shape much if any and though it is dangerous, painful and expensive it is way easier than losing weight. I recommend it.

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