The comic Steven Wright once said that his mom made only two dishes for dinner: take it or leave it.

That's the same menu choices offered by researchers in San Diego when they told fourth-graders, "Hey, wanna grow a carrot?" (Take it). Or "Don't ever eat bad-for-you food." (Leave it.)

Guess what happened?

In a school-based nutrition program (Shaping Healthy Choices), fourth-graders become healthier when offered fun nutritional options such as gardening and choosing lunch from a cafeteria salad bar; had nutrition messages integrated into the curriculum; and got their parents involved with nutrition newsletters.

At the start of the school year, 56 percent of students were overweight. By the end, 38 percent. Their average Body Mass Index fell 9 points.

WHOA! That's a super change!

Schoolmates not in the program didn't lose weight or eat better, despite being told to avoid sweetened drinks and other unhealthy foods. Seems teaching good nutrition habits and growing your veggies inspire; negative messages misfire.

A free Shaping Healthy Choices program toolkit will be available online later this year. (In the meantime, other effective programs include Healthcorps.org for high-schoolers and the Cleveland Clinic's Food is Knowledge Program for K-2.)

To fund program components that take some cash, schools can run auctions, carwashes or sell a recipe book that the kids put together.

Old-school thinking was that vendors and marketers of fast food, candy and soda could put their products in schools to help raise cash. That's a case in which it's better to leave it than take it.

© 2014 Michael Roizen, M.D. and Mehmet Oz, M.D.
Distributed by King Features Syndicate, Inc.