The New York Times reported a study, published last year in the journal Circulation that looked at nearly 9,000 Australians and found that for each additional hour of television a person sat and watched per day, the risk of dying rose by 11%. In that article, a doctor is quoted as saying that excessive sitting, which he defines as nine hours a day, is a lethal activity.

Ironically I was sitting with my iPad reading the latest HBR articles and found this article by Nilofer Merchant… She’s says

You might already know that the death rate associated with obesity in the US is now 35 million. But do you know what it is in relationship to Tobacco? Just 3.5 million.

Health studies conclude that people should sit less, and get up and move around. After 1 hour of sitting, the production of enzymes that burn fat declines by as much as 90%. Extended sitting slows the body’s metabolism affecting things like (good cholesterol) HDL levels in our bodies. Research shows that this lack of physical activity is directly tied to 6% of the impact for heart diseases, 7% for type 2 diabetes, and 10% for breast cancer, or colon cancer.

Follow this link for her full article.
http://blogs.hbr.org/cs/2013/01/sitting_is_the_smoking_of_our_generation.html