Scientists have come up with proof that watching television can be bad for your health.
A team from the Harvard School of Public Health studied 50,000 women over a six year period to determine whether changes in their patterns of television watching or sitting around at work led to an increased likelihood of obesity or type 2 diabetes.
The researchers, led by Dr Frank Hu, an expert in nutrition, found that watching television for an extra two hours a day increased the rate of obesity by 25%, and diabetes by 14%.
"
I have a treadmill in front of a TV so that I can do some exercise while watching the news
"
Dr Frank Hu
This was even after factors such as smokingand diet had been taken into consideration.
There was also bad news for office workers. The risks of obesity and diabetes also increased with every additional two hours spent sitting down at work - though these were much smaller than the risks from watching the box for the same length of time.
Dr Hu said he was not surprised that watching television seemed to have such a powerful effect.
"Compared with other sedentary behaviours, TV watching is associated with lower resting metabolic rate.
"Also, people tend to eat junk foods while watching TV, due to constant exposure to food commercials."
Exercise
The researchers also found that basic exercise had a signficant positive effect on obesity and diabetes rates.
Every additional two hours per day spent walking or standing at home cuts the risk of obesity by 9%, and the risk of diabetes by 12%.
Brisk walking for an hour per day was enough to drop the risk of obesity 24%, and diabetes by 34%.
The researchers have calculated that adopting a relatively active lifestyle can prevent nearly a third of new cases of obesity and over 40% of new cases of diabetes.
They define this healthy lifestyle as no more than 10 hours television per week, and at least 30 minutes of brisk walking per day.
Dr Hu said: "We should not only promote increasing physical activity levels but also target a decrease in sedentary behaviours, especially prolonged TV watching.
"Personally, I have a treadmill in front of a TV so that I can do some exercise while watching the news."
On average Americans watch four to five hours of television per day, making it the most prevalent and pervasive sedentary behaviour in the US.
The research is published in the Journal of the American Medical Association.
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