The average adult watches almost five hours of television per day, according to the article’s authors. Some efforts to prevent and reduce obesity have focused on modifying diet and physical activity, but newer strategies have involved reducing sedentary behaviors such as TV watching. Not only may reducing TV time allow time for more active endeavors, it may also help alleviate chronic sleep deprivation, potentially linked to obesity.
Jennifer J. Otten, Ph.D., R.D., a former UVM doctoral student now at Stanford University School of Medicine, and colleagues Jean Harvey-Berino, Ph.D., UVM professor and chair of nutrition, and Benjamin Littenberg, M.D., UVM professor of medicine, conducted a randomized controlled trial of 36 adults who had a body mass index between 25 and 50 and reported watching at least three hours of TV per day. Between January and July 2008, all participants underwent a three-week observation period during which their daily TV time was assessed. A group of 20 individuals was then randomly assigned to receive an electronic device that shut off the TV after they had reached a weekly limit of 50 percent of their previously measured TV viewing time. An additional 16 participants served as a control group.
As assessed by an armband measuring physical activity, those with the lock-out systems burned 119 more calories per day during the three-week period. In comparison, the control group burned 95 fewer calories per day during the intervention than during the observation period.
“I was surprised at the magnitude of the change — more than 100 calories expended daily — that was achieved with no real overt physical activity,” says Harvey-Berino. “We tried to recruit people who represented the average American television viewer, watching an average of three to five hours per day. But we have become so incredibly sedentary as a society, that a 50 percent reduction in viewing still made a huge difference.”
The authors report that this is the first study to measure the effects of a TV reduction intervention in adults. Previous research with children has found that screen time reductions reduce calories consumed but do not increase calories burned, producing a similar change in energy balance but through a different mechanism, the authors note.
“This research sends a strong message — to lose weight, turn off your TV,” says Littenberg.
This project was supported in part by USDA Hatch Act Funds and by grants from the National Institutes of Health. To link to recent news articles written about the study, visit U.S. News & World Report3 and New York Times4.
(This release was adapted from a December 14, 2009 news release produced by JAMA/Archives Media Relations.)