The moral of the story is: It's a confusing world, kids.

The release of Shrek the Third on May 18 will bring the usual onslaught of promotional products, including candy, soda and sugary cereal. Grocery aisles will ring with "I wants" from the grade-school crowd.

At the same time, television is featuring Shrek public-service ads beseeching increasingly overweight youngsters to "get up and play an hour a day."

Talk about a mixed message.

Are kids supposed to exercise before or after downing a Shrek Pop Tart?

Harvard's Campaign for a Commercial-Free Childhood wants the U.S. Department of Health and Human Services and vaunted Ad Council to fire their latest spokesman.

But who better than a plump ogre to lure kids off the couch? They're more likely to listen to him than a scrawny marathoner like Road Runner. Shrek has more cred these days than Santa, Mickey Mouse and the Easter Bunny - combined.

The percentage of overweight young people has more than tripled since 1980, according to the Centers for Disease Control and Prevention. That's alarming. The extra pounds are translating into serious health risks, particularly the early onset of diabetes.

That's why the Institutes of Medicine last week recommended new standards for school snacks and foods that sharply limit calories, fat and sugar. The new guidelines would apply to foods sold outside cafeterias, as in vending machines or fund-raising sales. The state of New Jersey and Philadelphia School District led the nation in making such nutritional improvements.

The nation must help kids eat better and get more exercise. But campaigns can go overboard - as when Sesame Street nixed "C is for Cookie" from Cookie Monster's song book. Some Jersey schools are banning birthday cupcakes.

Children need to learn healthy moderation, not deprivation.

As for Shrek, aim the outrage at the junk food tie-ins. Let him lead calisthenics.