Television, music, movies and other media appear to significantly increase obesity rates, tobacco use and other negative health issues among children and teenagers, according to a study published on Tuesday.

“The results clearly show that there is a strong correlation between media exposure and long-term negative health effects to children,” said Ezekiel Emanuel of the National Institutes of Health, lead researcher on the study.

The study led by researchers at the US National Institutes of Health, Yale University and the California Pacific Medical Centre analyzed 173 studies done since 1980 about the effects of media consumption on children. The researchers wanted to see how media exposure influenced children’s health in regarding tobacco use, sexual behavior, childhood obesity, attention deficit disorder with hyperactivity, academic performance, drug use and alcohol use.

Overall, 80 percent of the studies showed that greater media exposure led to negative health effects in children and adolescents. The greatest link was found between media and obesity with 96 percent of 73 studies finding a strong relationship between increased screen time and obesity. Next, 88 percent of 24 studies analyzing how media influenced tobacco use found a strong relationship between increased media exposure and an increase in smoking at an early age. Also, 93 percent of studies found that children with greater media exposure have sex earlier.

The situation is worse than this. In general, a modern child spends about 45 hours a week with TV, whereas he spends 30 hours at school and just 17 hours with his parents. “The average parent doesn’t understand that if you plop your kids down in front of the TV or the computer for five hours a day, it can change their brain development, it can make them fat, and it can lead them to get involved in risky sexual activity at a young age,” said Jim Steyer, the chief executive of Common Sense Media.

There are also studies that found a series of advantages for the use of the Internet among teenagers, but their number was very small, therefore insignificant to encourage the use of media in the case of children and teenagers.

“I think we were pretty surprised by how overwhelming the number of studies was that showed this negative health impact,” Dr. Emanuel said.

Therefore, the authors of the study recommended that patents place limits on the amount of media their children consume, ensure they watch programs appropriate to their age and encourage them to spend more time playing outside. Many studies have shown that outdoor activities are replaced in modern days by watching a movie or playing a video game. Earlier this year, a study led by Oliver Pergams, visiting research assistant professor of biological sciences at the University of Illinois at Chicago, noted a steady decline in per capita visits to US national parks since the late 1980s. The study found that during the decade from 1981 to 1991, per-capita nature recreation declined at rates from 1 percent to 1.3 percent per year, depending on the activity studied. The typical drop in nature use since then has been 18-25 percent.

The decline is correlated with the increase of the time spend to watch movies or playing game, in a shift defined by the researchers as “videophilia.”

“Videophilia has been shown to be a cause of obesity, lack of socialization, attention disorders and poor academic performance,” Pergams explained at the time.