Thinking You're Less Active Than You Are Could Be Killing You

A study found that people who said that they weren't exercising as much as their peers were much more likely to live shorter lives, even if they get plenty of exercise.

People who believe they are not exercising enough are more likely to suffer the consequences of inactivity whether or not they are sedentary, while those who believe they are active are more likely to be healthy even if they aren’t working out, according to new Stanford University research.

Published in the journal Health Psychology on Thursday, the findings suggest that mental states play a key role in healthfulness to the point that the placebo effect might improve fitness.

“Most people know that not exercising enough is bad for your health,” said study co-author Octavio Zahrt, a doctoral candidate in organizational behavior at the Stanford University Graduate School of Business. “But most people do not know that thinking you are not exercising enough can also harm your health.”

Drawing from United States government data that tracked perceptions among more than 61,000 adults starting as early as 1990, Zahrt and Stanford psychology professor Alia Crum deduced that people who said they were not as active as their peers were as much as 71 percent more likely to have died when the researchers followed up on their status in 2011.

The data also contained information about the respondents’ physical activity, including information from accelerometers that measured some participants’ movements over the course of a week.

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But respondents’ answers about their activity didn’t necessarily mesh with their behavior. In other words, some folks who claimed to be active were not while those who felt inactive got plenty of exercise.

The study was correlative, meaning the researchers can’t say for sure why more people said they didn’t exercise enough before they died. But Crum’s other research suggests that mindset can play a role in improving or harming one’s health.

The psychologist has shown that hotel maids’ health improved — they lost weight, for example — when they realized that their jobs afforded them the physical exercise they needed. She has also shown that tweaking milkshake labels to make them appear fattening or healthier can trick the body into producing more or less hormones that stimulate hunger.

For those who were healthier simply because they felt like they exercised plenty, they might be responding to the placebo effect. “Not only do placebo effects exist with medications — if you take a pill and believe it’s going to help you, it’s going to help you more — but the exact same could be happening with behavior,” said Zahrt.

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Zahrt and Crum are now conducting additional research to determine if they can measure health improvements among those who might believe they are sufficiently active.

On the other hand, people who don’t believe they are exercising enough might suffer from stress, anxiety and depression because of the invidious comparisons they are drawing between themselves and people around them. Whether or not they are active enough would be irrelevant to those people.

Zahrt has personal experience with that phenomenon. She proposed the study with Crum when she moved from Europe to Northern California a few years ago.

“I thought I was really fit even though I just cycled to work in the morning and went to the gym once a week,” she said. “I came here and I suddenly was surround by these crazily fit Californians. I was worried about my behavior. I just didn’t feel as healthy as I was before.”

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