Kids Eat 30 More Calories After Commercials for 'Unhealthy' Foods, Study Finds Study found 80 percent of all food ads are for "unhealthy" snacks and foods.

 -- Children are more likely to chow down on extra calories immediately after watching a food ad for an "unhealthy" treat, according to an analysis of several studies published today in the medical journal Obesity Review.

Researchers from multiple institutions including The Hospital for Sick Children Research Institute, Toronto, Canada, look at 29 different studies to understand how children between the ages of 2 to 18 were affected by advertising for food. The studies looked at data from 5,814 children to understand how they reacted to food commercials on television. Researchers found children are bombarded by advertising, seeing an average of five food ads per hour with 80 percent of these ads marketing what the researchers termed "unhealthy" -- or high calories, low nutrient -- foods.

Additionally they found children were more likely to consume another 30 calories within 15 minutes of watching ads for unhealthy foods, possibly contributing to overall weight gain. There were some limitations to this analysis. The authors of this meta-analysis pointed out that half of the studies they reviewed, either the subjects or researchers had information about how the study was designed that could have lead to bias, which could then have affected the results of that particular study. They called for more research to bolster their findings.

"The evidence indicates that unhealthy food and beverage marketing increases dietary intake and preference for energy-dense, low nutrition products in children during or shortly after exposure to advertisements," the researchers noted in the study, explaining more research was still needed. “Overall, our analyses support the need for a review of public policy on child-targeted unhealthy food and beverage marketing."

Dr. Keith Ayoob, a pediatrician and director of the Nutrition Clinic at the Albert Einstein School of Medicine, said that parents should not feel their children are doomed if they consume media.

"Parents need to know that they can make changes in their kids’ diets or at least what’s available to their kids, irrespective of what’s advertised," Ayoob told ABC News. "Parents don’t have to feel victimized by it. There’s plenty that parents can do, whether or not their kids see food advertisements."

Ayoob advised keeping screen time to a minimum of two hours a day and creating a healthy eating environment in the home, where children have healthy food options.

"It’s great to have kids give suggestions, but give them healthy options so that their choices become what kinds of fruit we’re going to have or what kind of whole grain cereal we’re going to have or what kind of yogurt we’re going to have," Ayoob said. "Those are good healthy options where kids can have a good influence."

Dr. Mary Carr is a general surgery resident at the University of Colorado. She is a medical resident in the ABC News Medical Unit.