Computer was where I gained my weight...went from a 155lb twiglet to 290lbs at the worst.
Just sitting there, with a 2 liter of soda, and a large bag of corn chips....enough of that, and anyone will swell up.
It's not the computer or the TV, it's just how lazy people are becoming...they want nothing but pampering 24/7....go out, get dirty, and get some excercise.