The study, published in The American Journal of Clinical Nutrition, analysed 28 studies from seven countries that explored the relationship between children drinking cow's milk and the risk of being overweight or obese.
All studies together involved almost 21,000 children between age one and 18 and showed that children who drank reduced-fat milk have a lower risk of being overweight or obese.
Eighteen of the 28 studies suggested children who drank whole milk were less likely to be overweight or obese, the study said.
"All of the studies we examined were observational studies, meaning that we cannot be sure if whole milk caused the lower risk of overweight or obesity. Whole milk may have been related to other factors which lowered the risk of overweight or obesity," said study lead author Jonathon Maguire from St. Michael's Hospital in Canada.
The findings challenge Canadian and international guidelines that recommend children consume reduced-fat cow milk instead of whole milk starting at age two to reduce the risk of obesity.
"The majority of children in Canada and the United States consume cow's milk on a daily basis and it is a major contributor of dietary fat for many children," Maguire said.
"In our review, children following the current recommendation of switching to reduced-fat milk at age two were not leaner than those consuming whole milk," Maguire added.
( With inputs from IANS )