Whole milk may be healthier for children’s weight than low-fat milk, a review of studies suggests.

The American Academy of Pediatrics currently recommends switching to skim or low-fat (1 percent) milk at age 2.

Canadian researchers analyzed 14 prospective studies including 20,897 children up to 18 years old. The studies compared children who drank whole milk (3.25 percent fat) with those given milk containing less than 2 percent fat.

Combining the data from these studies, the scientists calculated that compared with children who drank low-fat milk or skim milk, those who drank whole milk were at a 39 percent reduced risk for overweight or obesity, and the risk for obesity declined steadily as whole milk consumption increased. The analysis is in the American Journal of Clinical Nutrition.

The authors speculate that are several possible mechanisms. It may be that children who drink whole milk consume fewer calories from other food. Some studies suggest that milk fat has properties that make people feel full. Reverse causality could also be at play: It’s possible that skinny children have parents who offer them whole milk to fatten them up.