BAKERSFIELD, Calif. -- With one-third of American children either overweight or obese, schools are searching for ways to help kids eat leaner, healthier meals.

The New York City Department of Education has found a simple solution that made a big impact on its students.

Between 2005 and 2006, the public schools phased out the use of whole milk and replaced it with low-fat or skim milk. Even flavored milks such as chocolate were only available in reduced-fat form.

Officials were somewhat concerned that students would stop drinking milk altogether, thereby lowering their intake of vital nutrients such as calcium and vitamin D.

But in a new study, researchers from the New York City Health department found milk drinking was actually up slightly in 2009. And the switch to low-fat and skim choices has saved each milk-drinking student nearly 6,000 calories and 600 grams of fat each year.

Citywide, this translates to a reduction in billions of calories -- a savings that will help keep kids' weight gain in check as they grow older.