Australian researchers examined data from the Australian Bureau of Statistics and from a lifestyle study involving 11,000 people. Crunching the data, their study suggests that every single hour of TV viewed after the age of 25 reduces the viewer's life expectancy by 21.8 minutes.

The researchers from the University of Queensland also found that people who watch six hours of TV a day can expect to live 4.8 hours less than those who do not watch TV.

The researchers are careful to point out that there isn't necessarily a direct link, only that prolonged TV watching tends to correspond to a less healthy lifestyle, including poor diet and not enough exercise, which increases the risk of developing obesity, diabetes and heart disease.

Although the study was conducted using Australian figures, the researchers said the numbers are likely to be comparable in other industrialized countries where TV-viewing patterns are the same.

The findings are published in the British Journal of Sports Medicine.