Americans are a lot heftier than they were in 1988, but it's not because they're eating a lot more than they were a couple of decades ago; it's because they're sitting around a lot more, according to a new study. Researchers found that daily intake of calories changed little between 1988 and 2010, but the number of people who said they didn't do any physical activity in their spare time soared from 19% to 52% in women, and from 11% to 43% in men, the Los Angeles Times reports. "We wouldn't say that calories don't count, but the main takeaway is that we have to look very carefully at physical activity," says the lead researcher, a Stanford Medical School professor of gastroenterology. "The problem is not all in the intake of calories," he says, noting that "most people don't walk or bike to work, and most people are not in jobs that require physical activity."
The prevalence of obesity rose from 25% to 35% in women over the time period, and from 20% to 35% in men. But in an editorial accompanying the study, the managing editor of the American Journal of Medicine says the solution to obesity isn't as simple as telling people to get off the couch, CBS News reports. "If you are spending your time and energy just eking out a living for your family, it's not surprising that you're not exercising," she says. And food isn't off the hook completely, the director of policy at the World Obesity Federation tells the Guardian, explaining that eating habits need to change to match today's more sedentary lifestyles. "While it may be possible to raise your physical activity enough to match the amount of food you eat, it is not easy, so the message still has to be 'cut the calories' or perhaps 'cut your calories to match your physical activity level,'" he says. (Read more obesity stories.)