People who perceived themselves to be less fit than others are at greater risk of death when compared to those who viewed themselves as being more fit than their peers—even after accounting for people's actual levels of fitness, according to a new study in Health Psychology.
Past studies have shown that self-perception of one's own health can have physiological consequences, according to NPR's "Shots." For instance, Alia Crum, study author and psychologist at Stanford University, in previous research assessed the physical health of hotel attendants before and after a presentation demonstrating that their everyday job activities—which included heavy lifting and lots of walking—were a good form of exercise.
Crum explained that many of the attendants before the presentation "didn't have the mindset that their work was good exercise." After the presentation, however, she tracked the women for a month and found that those "who started to look at their work as good exercise had improvements in blood pressure and body fat."
For the latest study, Crum and co-author Octavia Zahrt, a PhD. candidate in health psychology at Stanford's Graduate School of Business, looked at data on 61,141 people who participated in one of two national health surveys: the National Health Interview Survey or the National Health and Nutrition Examination Survey. Based on the data, researchers were able to track respondents' health and mortality over a 21-year follow-up period.
According to the Pacific Standard, people enrolled in either survey were asked to disclose demographic information, as well as whether they thought they were "physically more active, less active, or about as active as other persons your age." The surveys then assessed how active respondents actually were by providing them a list of physical activities and asking respondents to select which ones they had done in the last few weeks. If the respondents said they had done one or more of the activities, they were asked to provide more information detailing how frequently they had completed those activities and for how long.
In addition, a subset of around 9,000 people in the surveys agreed to wear accelerometers for seven days, which gave researchers an exact record of respondents' physical activity.
Overall, the researchers found that "the less active individuals perceived themselves to be, as compared with other people their age, the more likely they were to die in the [21-year] follow-up period" than those who believed they exercised more than others their age. In fact, in one sample, people who perceived themselves as less active than their peers were 71 percent more likely to die than those who felt they exercised more than their peers.
Crucially, according to the researchers, "this result held when controlling for actual amounts of activity, either as reported in the detailed questionnaires or through accelerometer data."
There are a couple of potential explanations for the results, Crum and Zahrt said.
First, according to the researchers, the placebo effect's "dark side" could come into play. Crum explained, "What placebo underpins is the effect of our mindset," such as how "the belief you're getting a pain medication can activate endogenous opiates in the brain." In this case, Crum suggested the reverse might be happening—someone's constant fear that he or she isn't exercising enough could lead to poorer health.
Other possible explanations could be that fears about being inactive could exacerbate stress or depression—which both affect health—or lead to a self-fulfilling prophecy, the researchers said. "People who think they are less active can be discouraged by that perception, and they might stop exercising and become less active over time," Zahrt said.
Angelina Sutin—a behavioral scientist at Florida State University College of Medicine, who was not involved in the study—said the study "adds a piece of this perception puzzle we're trying to work through."
However, she cautioned that it's difficult to pin down exactly what causes the effects this study found. "We don't have a real grasp on what the mechanism is yet," she said, noting the study found only correlation between self-perception and health outcomes, not causation.
Despite that Crum and Zahrt said the findings suggest using intimidating language to try to inspire people to work out could backfire. "If you tell people they need to get this really high level of activity or else they have all these healthy complications and die early, you might just be instilling this negative mindset," Zahrt said.
Crum added that messaging should find a balance between accurate information on health and exercise without veering into scare tactics. "Finding the right balance may be a challenge, but carefully crafted campaigns that promote behavior change while simultaneously instilling positive perceptions are likely to be the most effective," the researchers said.
Overall, as Crum put it, "The ultimate end goal is the sense of enoughness." She added, "It's all individual. If you're thinking, every day, that you haven't done enough, that is problematic" (Chen, "Shots," NPR, 7/20; Jacobs, Pacific Standard, 7/20).
Understand the wellness spectrum
Programs aimed at promoting healthy habits among employees are likely to lead to improved employee engagement and productivity—but they're unlikely to reduce the total cost of care. To do that, you'll need to take a population health approach.