A new U.S. study finds that sixth-grade girls who drink two daily servings of milk cut their risks of obesity, and boys of the same age who played on a sports team were also at a healthier weight.

The study, published online in the journal Pediatrics, reveals some gender differences in how daily habits may influence obesity among young children.

Conducted by researchers at the University of Michigan Medical School, the study looked at data from 1,714 sixth-grade students living in the state.

Milk consumption seemed to protect girls from obesity, but made no difference for boys, the researchers said. Meanwhile, participation in a school sports team cut obesity risks for the boys, while the association wasn't as strong for the girls, the findings showed.

Also, 61 per cent of obese boys and 63 per cent of obese girls reported watching television for two or more hours a day. Obese girls were more likely than any other group to use a computer. Meanwhile, obese boys reported playing video games more often than normal-weight boys, although the association was not as strong as in other studies.

The evidence follows mounting research on the effects of habits such as playing video games, eating fast food, and watching television on the waistlines of children.

"Additional work is needed to help us understand the beneficial impact of improving school lunches and decreasing screen time," says cardiologist and senior study author Dr. Elizabeth Jackson, assistant professor of internal medicine. "Presumably playing video games or watching TV replaces physical activity."

The Mayo Clinic in the US recommends you start small when it comes to helping your child lose weight. Make small, gradual changes, such as turning off the television during dinner, switching from soda or sugary beverages to low-fat milk or water, and introducing activity into your child's life, such as taking a family walk or getting involved in a sports program.

Access the study: http://pediatrics.aappublications.org/content/early/2013/08/07/peds.2012-2994.abstract?sid=0092bf72-01b8-4586-a2b2-708e427dd080