The specially designed video games increased the players' consumption of fruits and vegetables by about two-thirds of a serving per day, but the children did not exercise more. (Paul Sakuma/Associated Press)

Children who played video games designed to encourage healthier eating and exercise consumed only slightly more fruits and vegetables, a U.S. study has found.

The games, Escape from Diab and Nanoswarm: Invasion from Inner Space, are designed to lower risk of obesity and Type 2 diabetes by changing the diet and physical activity behaviour of young people.

"Diab and Nanoswarm were designed as epic video game adventures, comparable to commercial quality video games," said the study's lead investigator, Tom Baranowski of Baylor College of Medicine in Houston and the U.S. Department of Agriculture's research service.

"These games incorporated a broad diversity of behaviour change procedures woven in and around engrossing stories," he added in a release.

The study in the January 2011 issue of the American Journal of Preventive Medicine looked at children aged 10 to 12.

Researchers randomly assigned 103 children to a treatment group that played Diab and Nanoswarm, and 50 to a control group that played diet and physical activity knowledge games on popular websites.

Children in the treatment group increased their consumption of fruits and vegetables by about two-thirds of a serving per day — still not enough to reach the minimum daily recommended amount of produce, the researchers found.

The Canada Food Guide recommends that girls and boys aged nine to 13 eat six servings of fruits and vegetables per day. Canada's Physical Activity Guide recommends at least 90 minutes a day of exercise for children and youth.

The participants also did not increase water consumption or moderate to vigorous physical activity, or improve body composition, based on measurements of their height, weight, waist size and triceps skin-fold thickness.

Physical activity was monitored for at least four days using accelerometers that attach to a belt around the waist and record movement. Dietitians evaluated the children's food consumption using 24-hour diet recalls.

The games were designed by Archimage, Inc., and funded by a Small Business Initiative Research Grant from the U.S. National Institute of Diabetes and Digestive and Kidney Diseases of the U.S. National Institutes of Health.