Drinking whole-fat milk may make kids leaner

In the study, children who drank whole milk (containing 3.25 per cent fat content) had a body mass index (BMI) score of 0.72 units lower than those who drank one or two per cent low-fat milk.

That's comparable to the difference between having a healthy weight and being overweight, said lead author Jonathon Maguire, paediatrician at St. Michael's Hospital in Ontario, Canada.

It may be because children who drank full-fat milk were likely to end up less hungry, making them less likely to snack on high calorie foods, the researchers explained.

Further, children who drank one cup of whole milk each day had better vitamin D levels -- known to protects bones and immune system -- than those who drank nearly three times as much skimmed milk.

This could be because vitamin D is fat soluble, meaning it dissolves in fat rather than water. Milk with higher fat content therefore contains more vitamin D. 

"Children who drink lower fat milk don't have less body fat, and they also don't benefit from the higher vitamin D levels in whole milk," Maguire said, adding "it's a double negative with low fat milk."

For this study, published in the American Journal of Clinical Nutrition, researchers studied 2,745 children ages two to six years. 

The findings indicate a need to closely examine existing nutritional guidelines that recommend two servings of low fat (one per cent or two per cent) milk for children over the age of two to reduce the risk of childhood obesity, the researchers suggested.