By Rob Stein, The Washington Post.
Prolonged TV viewing is the most prevalent and pervasive sedentary behavior in developed countries and increasingly widespread in developing countries. Although TV viewing has been associated with morbidity and mortality, systematic and quantitative assessment of published studies is not available.
Aders Grøntved of the University of Southern Denmark and Frank Hu of the Harvard School of Public Health conducted a systematic analysis of every study that was published between 1970 and 2011 linking TV viewing and an increased risk for type 2 diabetes, cardiovascular disease and premature death. Eight large studies from the United States, Europe and Australia were included in the so-called "meta-analysis." This study has just been published in The Journal of the American Medical Association.
More than two hours of TV watching each day increased the risk for type 2 diabetes and heart disease, while more than three hours of daily TV viewing boosted the risk for premature death, the researchers concluded. Every additional two hours of TV a day increased the risk for diabetes, heart disease and premature death by 20 percent, 15 percent and 13 percent respectively, the researchers found.
Based on the findings, the researchers estimated that every 100,000 people in the United States, every two-hour increment in TV viewing per day was associated with 176 new cases of type 2 diabetes, 38 new cases of fatal heart disease and 104 new cases of death from any reason per year.
Not surprisingly, the increased risk is apparently due at least in part to the increased risk for obesity, the researchers said.
"The message is simple. Cutting back on TV watching can significantly reduce risk of type 2 diabetes, heart disease and premature mortality," Hu said in a written statement released with the study. "We should not only promote increasing physical activity levels but also reduce sedentary behaviors, especially prolonged TV watching."