It’s easy—and tempting—to settle in for a marathon session with your favorite TV show, but that indulgence may come back to haunt you.
In a study of people at higher risk of developing diabetes, researchers say that every hour spent sitting can increase the risk of developing the metabolic disorder by 3.4%. For a day-long binge, that could be as much as a 30% higher risk. “With streaming TV, you can watch a program continuously; instead of watching just half an hour once day a week, you can watch a whole season in a day, so we expect to see increases in sitting to continue,” says Andrea Kriska, an epidemiologist at the University of Pittsburgh and senior author of the paper on the effects of TV on diabetes risk in the journal Diabetologia.
Kriska is part of the Diabetes Prevention Program Research Group, which found that people who spent more time sitting, whether in front of the TV or at work, were more likely to develop diabetes than those who sat less, regardless of how much they exercised.
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The group started with the population of people at higher risk of developing diabetes who were enrolled in the Diabetes Prevention Program. Some were assigned to exercise at least 150 minutes at a moderate level each week and change their diet with the goal of losing 7% of their body weight. Others were given the diabetes drug metformin, and another group was given a placebo. In 2002, after more than three years, those who adopted the lifestyle changes lowered their risk of developing diabetes by 58%, compared to 31% for those taking the drug.
More and more data suggest that to reduce disease, it's not just enough to exercise more; you have to sit, less too. The scientists wanted to see what role, if any, sitting played in this reduction. Did being more physically active lead to helping people be less sedentary? And did time spent sitting have any connection with the rate of diabetes?
“What we found was yes, and yes,” says Bonny Rockette-Wagner, from the department of epidemiology at Pittsburgh. “There is an independent effect of sitting behavior on diabetes incidence that does not have to do with physical activity. It’s an independent, additional effect.”
The researchers asked the 3,232 people in group how much time they spent sitting at work and how much time they spent watching TV, as a proxy for their total sedentary time. They also asked them about their leisure time physical activity and measured their blood glucose levels. After three years, the lifestyle group spent fewer hours sitting than the metformin and placebo groups, despite the fact that sitting less was not a specific goal of the program. And the more time they spent off their chairs, the lower their risk of going on to develop diabetes.
The results suggest that efforts to help high-risk people avoid diabetes should include a goal of sitting less. That’s what Kriska and Rockette-Wagner are starting to do in their community sessions in which they teach people about the Diabetes Prevention Program. Instead of focusing exclusively on the target of 150 minutes of exercise each week, they're asking people to think about sitting less, starting by spending a few minutes fewer on the couch each day and building up to becoming more active.
The researchers admit that simply sitting less won’t replace being physically active, but after so much focus on getting sedentary people to move, getting them to think about sitting less may be just as productive.