Scientists did a
calorimetric test to
determine energy consumption while watching
TV. What they found
surprised them. They found that on average people watching
TV consumed ten per cent
less energy than normal
resting energy consumption. That's right, you actually consume more energy sitting there doing nothing than when you are watching
TV.
There is a simple explanation. It seems that this is due to the concentration people exert while watching TV reducing the amount of fidgeting and random movement people do.