Sitting at your desk for long periods of time is, in technical terms, really, really bad for you.
Sit for much of the day and you won't just get fatter; as Jessica Stillman notes, it can also make you dumber. Sit for more than six hours a day and you are 18% more likely to die from diabetes, heart disease, and obesity than people who sit less than three hours a day.
And here's the kicker. Sit for more than 11 hours a day and you are 40% more likely to die in the next three years compared to those who sit for less than four hours.
Of course eleven hours may sound like a lot...but take a second and add up all the time you spend at your desk, in your car, and on your couch. Odds are you're pretty close to 11 hours.
Clearly whoever invented sitting did not have our best interests at heart.