A new study adds to the body of research linking TV-watching to increased consumption of junk food, finding that TV may have more of a negative effect on snacking than other screen time, such as playing video games. One suspected culprit: tempting commercials for unhealthy snacks.

The study, presented at the American College of Cardiology's 63rd Annual Scientific Session, examined 1,003 middle school-aged kids from 24 middle schools in Southeast Michigan communities participating in Project Healthy Schools. Questionnaires asked about type and frequency of screen time among other lifestyle habits, such as snacking and food and beverage choices. Blood pressure, cholesterol, height, weight and recovery period after exercise were also measured.

Students were subsequently divided into three groups: "low screen time", or less than 30 minutes per day, "high TV time," or two to six hours per day, and "high computer/video games," again for two to six hours each day. Physiologic markers and snacking habits were compared.

Researchers discovered kids who spent more time in front of a television or computer screen snacked more often, with such snacks of the unhealthy variety. Children in the "high" computer and television categories ate about 3.5 snacks each day, or "one full snack more" than those in the "low" group.

It was also found children in the "high" television group were more likely than the computer/video game group to consume fatty foods such as chips and French fries.

Researchers believe children who spend a lot of time in front of the television opt for less-healthy snacks because they are constantly subjected to commercials promoting snacks high in salt, sugar and bad fats. And unlike children playing video games or using the computer, these kids tend to have their hands free for "mindless snacking."

"The more we can change behavior early on to promote healthy weight and dietary habits, the more likely we will be able to reduce adult-related problems including heart disease, diabetes and high blood pressure," said study senior author Elizabeth Jackson, M.D., M.P.H., associate professor, Division of Cardiovascular Medicine, University of Michigan Systems, Ann Arbor, Michigan.