"The message is simple. Cutting back on TV watching can significantly reduce risk of type 2 diabetes, heart disease, and premature mortality," said senior author Frank Hu, professor of nutrition and epidemiology at HSPH.
"We should not only promote increasing physical activity levels but also reduce sedentary behaviour, especially prolonged TV watching," he added.
Hu and first author Anders Grontved, a doctoral student and visiting researcher in the HSPH Department of Nutrition, conducted a meta-analysis, a systematic assessment of all published studies from 1970 to 2011 that linked TV viewing with increased risk of type 2 diabetes, cardiovascular disease, and premature death.
Eight large prospective cohort studies from the United States, Europe, and Australia met the researchers'' criteria and were included in the meta-analysis.
The results showed that more than two hours of TV viewing per day increased risk of type 2 diabetes and cardiovascular disease, and more than three hours of daily viewing increased risk of premature death.
"Sedentary lifestyle, especially prolonged TV watching, is clearly an important and modifiable risk factor for type 2 diabetes and cardiovascular disease," Grontved added.
The study has been published in the Journal of the American Medical Association .
