Exercise and limited TV time may keep kids trim. This is the finding of a study by the The American Academy of Pediatric.
Talk about stating the obvious!... 
The report recommends that children
devote no more than two hours per day to watching TV and
playing video game.
Experts encourage children to exercise regularly. Some
groups, including the AAP, recommend that boys move enough to
take 13,000 steps each day, while girls should strive for
11,000. Another common recommendation is for children and
teenagers to get at least one hour of moderate exercise on
most, if not all, days of the week.
Full article from the Reuters website