Many children love sending and receiving text messages through their cell phones -- sometimes to the great annoyance of their parents.

But now a new study from the UNC suggests this technology could be used to reduce children's chances of becoming overweight or obese later in life, by helping them monitor and modify their own behaviors now.

Recent studies show that approximately 19 percent of youths aged 6 to 11 are overweight, and that 80 percent of overweight adolescents become obese adults.

"Self-monitoring of calorie intake and expenditure and of body weight is extremely important for the long-term success of weight loss and weight control," said Jennifer R. Shapiro, Ph.D., assistant professor of psychiatry in the UNC School of Medicine and principal investigator of the new study, which is published in the November/December 2008 issue of the Journal of Nutrition Education and Behavior.

"Unfortunately, both children and adults who are trying to lose weight often do not adhere to self-monitoring," Shapiro said. "They tend to be good about self-monitoring at the start of a weight-loss effort, butthen their adherence drops off over time."

Traditionally, paper diaries are the tool most often used for self-monitoring. People trying to lose weight write down how many calories they consume, how many calories they burn in exercise and how much they weigh. While a paper diary can be very effective, Shapiro and her colleagues had a hunch that the same concept might work better in children if they could report their self-monitoring via cell phone text messaging -- and receive feedback messages in return.

"Cell phone text messaging is something that's very familiar to most children now, since they've grown up with it," Shapiro said. "By using this technology, we were hoping to make self-monitoring seem more like fun to them and less like work."

Fifty-eight children aged 5 to 13 and their parents participated in Shapiro's study, which was conducted at UNC Hospitals, and 31 families completed the study. The families took part in three group education sessions (one session weekly for three weeks) which aimed to encourage them to increase physical activity, decrease "screen time" (time spent watching television) and reduce consumption of sugar-sweetened beverages. All of the children were given pedometers to track the number of steps they took each day, as well as goals to meet for the number of steps taken, minutes of screen time and number of sugar-sweetened beverages consumed per day.

The participating families were randomized into three groups: one that reported self-monitoring via cell phone text messaging, another group that reported self-monitoring in a paper diary, and a no-monitoring control group. The text messaging and paper diary groups answered three questions each day: (1) what was the number on your pedometer today?; (2) how many sugar-sweetened beverages did you drink today?; and (3) how many minutes of screen time did you have today?

Each family in the text messaging group was given a cell phone to be used only for study-related messages. They were instructed to send two messages per day (one from the parent and one from the child) reporting their answers to the three questions. Each time a message was sent, the sender received an immediate, automated feedback message based on what the sender reported. The researchers generated hundreds of feedback messages for the study. One example was, "Wow, you met your step and screen time goals -- congratulations! What happened to beverages?"

The study results show that children in the text messaging group had a lower attrition rate from the study (28 percent) than both the paper diary (61 percent) and the control group (50 percent).

The study concludes that cell phone text messaging may be a useful tool for self-monitoring of healthy behaviors in children, and suggests more broadly that novel technologies may play a role in improving health.