Exercise and Weight: It’s Complicated

ResolutionsWhat is the first thing people do when they resolve to shed some excess weight? Often they head to the gym. Self-help articles are full of suggestions for the best way to exercise for weight loss. Unfortunately, that stuff is mostly misleading. The relationship between exercise and weight is complicated.

As we’ve written before, exercise is a lousy way to lose weight. So when people adopt a new regime of physical activity regime, if they expect to lose weight with it, discouragement is often the result. Commitment fades into a lost opportunity.

But a new study in Obesity Reviews reiterates the conventional wisdom about exercise and weight: “Increased physical activity was the most consistent positive correlate of weight loss maintenance.”

However, it’s important to pay attention to the word “correlate” in that conclusion. The reality of the relationship between weight and exercise is that it’s not so simple.

Weight Maintenance Cause and Effect

Here’s the rub. Long-term outcome studies for behavior change are devilishly hard. Keeping people engaged in the study is hard. Maintaining behavior change is hard. So it’s hard to show that an intervention makes a difference at a very granular level.

Thus we wind up with correlation studies for long-term outcomes like weight maintenance. And a correlation study, like the one in Obesity Reviews, can’t prove effectiveness. John Speakman recently explained:

It is pretty clear that losing weight leads to increases in physical activity levels. It isn’t so surprising then that those people who regain weight become less active again, while those keeping it off do not. We need to be careful in inferring directions of causality here.

Exercise is clearly beneficial for our health – for many reasons. It’s probably important for maintaining a healthier weight over the long term.

The larger truth is this. Obesity is a problem of physiology. And thus, behavior change – like better exercise habits – can be a help, but not a reliable cure. The physiology of obesity can make exercise more difficult. So if you don’t address the medical issue of obesity, you’re not going to cure it with exercise alone.

We must focus on the whole person and their health.

Click here for the study in Obesity Reviews and here for further perspective in the New York Times.

Resolutions, photograph © Mark Bonica / flickr

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February 29, 2020

3 Responses to “Exercise and Weight: It’s Complicated”

  1. February 29, 2020 at 3:43 pm, Mary-Jo said:

    Yes, the frustration of correlation conclusions leaving lasting impressions on HCPs so that they can emphasize to patients with wide grins: “Move more! Eat less!”. 🙄 Moreover, how about the research suggesting that people with obesity, even people with a reduced BMI need to exercise twice as long, if not more, twice as hard to get results and then must increase even more to sustain results. I’ve often questioned why this is the case and have never really been given a good answer. I know it’s physiological, but exactly what mechanism(s)?

  2. February 29, 2020 at 8:00 pm, Alyson Shirer said:

    Respectfully disagree. Losing weight leads to increased activity? It’s the other way around being less active may lead to weight gain. Weight gain does not cause people to be less active, though it can certainly make it more difficult. You don’t need to do a research study to see that. It is evident in life experience. While there are some who may be predisposed to weight gain, this does not change the fact that choosing to be sedentary or eat excess calories leads to weight gain. Don’t sell people short. People have choices and sometimes we make good ones and some we don’t. In my opinion, saying people can’t help it is a cop out. I do treat it as a chronic disease and I do see long term success in those who maintain healthy behavioral choices.

    • March 01, 2020 at 4:52 am, Ted said:

      In your response, Alyson, you note that weight gain hinders physical activity. So, on some level you understand the facts here, despite your desire to disagree. Regarding long-term success through behavioral choices, careful studies show that this is the exception, rather than the rule. Behavioral changes can help one cope with obesity. But they do not cure it in most cases.