How does TV affect your activity?

What happens when people start watching less television? Do they eat less? Exercise more? Sleep better?
From an article at http://well.blogs.nytimes.com/

That is what researchers at the University of Vermont set out to learn in a fascinating six week study to monitor television viewing, physical activity and eating habits. As it turns out, watching less TV doesn’t necessarily lead to more exercise or better eating habits, but it does result in subtle but meaningful changes in overall activity levels, according to a new study in The Archives of Internal Medicine.

Using monitoring equipment attached to TVs, the researchers tracked the viewing habits of 36 men and women who were overweight or obese. Among the study subjects, the average amount of time spent watching television was five hours a day, similar to national trends.

For the next three weeks, 20 randomly selected study participants had their viewing cut in half. Based on their previous viewing habits, each person was given a weekly limit of TV time. Once the limit was reached, a monitor automatically shut the TV off and would not allow it to be turned on again until the next week. A control group of 16 people continued to watch the same amount as always. During both the first and second phase of the six week study, the participants also wore armbands for a week that measured their movements.

To the researchers’ surprise, cutting back television time didn’t have an effect on calorie consumption, nor did it change sleep habits. The group that watched less television did, however, move more, burning an average of 120 calories more a day than the control group.

Although some participants did report getting more exercise by walking their dogs more often or signing up for a yoga class, most of the people didn’t use their television-free time for scheduled physical exercise. One person used the extra time to organize photo albums, others reported reading more or playing board games with their children. Many said they spent the time doing more household chores or paying bills.

But even those minor changes in activity level counted a lot. While the group that reduced television viewing burned off an additional 120 calories a day compared with the previous three weeks, the control group became even more sedentary, moving about 100 calories less than before. The additional activity that resulted from less television time is the equivalent of walking about eight miles a week.

“A lot of people might say, ‘Of course people would move more with less television,’” said Jennifer J. Otten, now a postdoctorate research fellow at Stanford University School of Medicine. “What we were looking for was to see if there was a meaningful difference.”

Dr. Otten said the finding that eating habits weren’t changed by less television time was surprising. Earlier studies with children have found that reducing television time significantly reduced the number of calories a child consumed. The fact that a similar effect wasn’t found in adults may suggest that children are more easily influenced by food advertising on TV than adults.

Dr. Otten says the main lesson for adults is that reducing your television viewing time will result in a meaningful increase in activity even if you’re not using the time for strenuous exercise.

“Compared to watching television, you burn more calories reading, writing, doing desk work — pretty much any activity other than sleeping,” Dr. Otten said. “The main finding is that if you turn off the TV, you may burn more calories without really thinking too much about it.”