What is impact of watching too much tv (more than 4 hours) on young children under 5 ?

Young children/TV: While some educational and safe entertainment value can be extracted from TV in moderation, children under the age of 5 who watch more than 4 hours/day of TV are more likely to be overweight, are more likely to be aggressive if they watch violent shows and are more likely to be fearful that something bad might happen to them; TV also reinforces gender role and racial stereotypes. More below...