A study in Circulation showed that people who watch 4 hours of TV a day have an 80% higher risk of dying from heart disease than those who watch to hours or less. There was an associated increase in blood glucose and cholesterol. The findings were the same even if people exercised regularly. The message is to limit your TV watching and spend as much time on your feet during the day. Avoid sitting on a chair as much as you can.
See Circulation 2011.