(TIME.com) -- Got milk? It turns out that low-fat versions may not be the answer to helping kids maintain a healthy weight.

Long a staple of childhood nutrition, milk is a good source of calcium and vitamin D, which can help to build bone, and experts believed that lower-fat versions could help children to avoid the extra calories that came with the fat in whole milk.

But in a study published in the Archives of Disease in Childhood, scientists found that skim and low-fat milks may not be as useful for weight loss as experts had hoped.

Since 2005, both the American Academy of Pediatrics (AAP) and the American Heart Association (AHA) recommended that children drink skim or low-fat milk after age 2.

Because whole milk has more calories from fat than skim, 1% fat or 2% fat versions, the thinking was that the lighter varieties would help youngsters avoid weight gain and curb the growing problem of overweight and obesity in childhood.

Not all of the studies supported this idea, however; some found no relationship between the type of milk preschoolers drank and their body weight, while others found that skim milk drinkers were heavier than their whole milk-drinking counterparts.

So Dr. Mark Daniel DeBoer, an associate professor of pediatric endocrinology at the University of Virginia School of Medicine, and his colleagues turned to a large database of 10,700 children in the Early Childhood Longitudinal Survey, Birth Cohort to investigate the relationship between the type of milk children drank and their body mass index (BMI).

The survey tracked the long-term health of a population of American kids born in 2001, and the researchers interviewed the caregivers and parents of the kids when they were 2 and again when they were 4 about what kind of milk the kids drank: skim, 1% semi-skimmed milk, 2% milk, full fat milk or soy. When the children were 4 years old, the scientists also asked the parents about how often the children consumed other beverages, including fruit juices, sports drink and sugared sodas.