Want kids who are smarter and thinner? Keep them away from the television set as toddlers. A shocking study from child experts at the Université de Montréal, the Sainte-Justine University Hospital Research Center and the University of Michigan, published in the Archives of Pediatrics & Adolescent Medicine, has found that television exposure at age two forecasts negative consequences for kids, ranging from poor school adjustment to unhealthy habits.

"We found every additional hour of TV exposure among toddlers corresponded to a future decrease in classroom engagement and success at math, increased victimization by classmates, have a more sedentary lifestyle, higher consumption of junk food and, ultimately, higher body mass index," says lead author Dr. Linda S. Pagani, a psychosocial professor at the Université de Montréal and researcher at the Sainte-Justine University Hospital Research Center.

The goal of the study was to determine the impact of TV exposure at age 2 on future academic success, lifestyle choices and general well being among children. "Between the ages of two and four, even incremental exposure to television delayed development," says Dr. Pagani.

A total of 1,314 kids took part in the investigation, which was part of the Quebec Longitudinal Study of Child Development Main Exposure. Parents were asked to report how much TV their kids watched at 29 months and at 53 months in age. Teachers were asked to evaluate academic, psychosocial and health habits, while body mass index (BMI) was measured at 10 years old.

"Early childhood is a critical period for brain development and formation of behaviour," warns Dr. Pagani. "High levels of TV consumption during this period can lead to future unhealthy habits. Despite clear recommendations from the American Academy of Pediatrics suggesting less than two hours of TV per day -- beyond the age of two -- parents show poor factual knowledge and awareness of such existing guidelines."

According to the investigation, watching too much TV as toddlers later forecasted:

a seven percent decrease in classroom engagement;

a six percent decrease in math achievement (with no harmful effects on later reading);

a 10 percent increase in victimization by classmates (peer rejection, being teased, assaulted or insulted by other students);

a 13 percent decrease in weekend physical activity;

a nine percent decrease in general physical activity;

a none percent higher consumption of soft drinks;

a 10 percent peak in snacks intake;

a five percent increase in BMI.

"Although we expected the impact of early TV viewing to disappear after seven and a half years of childhood, the fact that negative outcomes remained is quite daunting," says Dr. Pagani. "Our findings make a compelling public health argument against excessive TV viewing in early childhood and for parents to heed guidelines on TV exposure from the American Academy of Pediatrics."

Since TV exposure encourages a sedentary lifestyle, Dr. Pagani says, television viewing must be curbed for toddlers to avoid the maintenance of passive mental and physical habits in later childhood: "Common sense would have it that TV exposure replaces time that could be spent engaging in other developmentally enriching activities and tasks which foster cognitive, behavioral, and motor development."

"What's special about this study is how it confirms suspicions that have been out there and shown by smaller projects on one outcome or another. This study takes a comprehensive approach and considers many parental, pediatric and societal factors simultaneously," she adds.

This research was funded by the Social Science and Humanities Research Council of Canada.

The article, published in the Archives of Pediatrics & Adolescent Medicine, was authored by Linda S. Pagani, Caroline Fitzpatrick and Tracie A. Barnett of the Université de Montréal and its affiliated Sainte-Justine University Hospital Research Center in Canada in collaboration with Eric Dubow of the University of Michigan in the United States.