(CBS NEWS) Drinking sugary beverages throughout childhood has been linked to childhood obesity before, but now researchers say they have found evidence of the risk in children who barely have reached kindergarten.
Childhood obesity rates have tripled over the past three decades in the United states. An estimated 17 percent of kids and adolescents aged 2 to 19 are obese.
Previous studies have suggested school-aged kidsand teens who drink sugary beverages daily are more likely to be overweight or obese than those who don't. The findings have been more mixed for younger children, according to the study's authors, led by Dr. Mark DeBoer, a pediatrician at the University of Virginia in Charlottesville.
"Even though sugar-sweetened beverages are relatively a small percentage of the calories that children take in, that additional amount of calories did contribute to more weight gain over time," DeBoer told Reuters.
For the study, published August 5 in Pediatrics, researchers tracked 9,600 kids between the ages of 2 and 5 years old who were involved in a study in which their parents were surveyed about their drinking and television watching habits. Sugary drinks included sodas, sports drinks and fruit drinks that were not 100 percent juice.
The children got body mass index (BMI) measurements, a number calculated from a child's weight and height.
Kids are considered overweight if their BMI is in the 85th to 95th percentile compared to other children of their gender and age, and are obese if their BMI is in the 95th percentile or greater. The American Academy of Pediatrics (AAP), the publisher of the journal this study is featured in, recommends BMI measurements for screening for overweight and obesity in kids beginning at 2 years old.
The study found the more sugary drinks a child consumed, the higher his or her BMI when measured at ages 4 and 5 years old. Specifically, 5-year-olds who drank sugary drinks daily were about 1.5 times more likely to be obese than those who didn't.
However, this effect was not yet seen in younger kids 2 years of age.
When the researchers conducted a prospective analysis of the 2-year-old children's sugary drink habits, they found sugary beverage consumption was linked to BMI increases over the following two years, suggesting this added weight over time could lead to obesity.
The researchers also found a greater proportion of kids who drank sugary drinks daily at ages 4 and 5 watched more than the pediatrician-recommended two hours of television per day.
"As a means of protecting against excess weight gain, parents and caregivers should be discouraged from providing their children with (sugar-sweetened beverages) and consuming instead calorie-free beverages and milk," wrote DeBoer and the researchers. "Such steps may help mitigate a small but important contribution to the current epidemic of childhood obesity."
They added that policy changes should be considered to further curb sugary drink consumption in kids. The American Medical Association has previously called for soda taxes, with the revenue used to fund obesity education, including a yearly curriculum for children
One expert not involved in the new study said the findings were not surprising.
"This is really just adding to the evidence we already know that (drinking) sugar-sweetened beverages in childhood is associated with weight gain," Dr. Y. Claire Wang, an assistant professor of healthy policy and management who studies childhood obesity at the Columbia University Mailman School of Public Health in New York City, said to Reuters. "It's definitely one of the major, if not the main, driver in childhood obesity," she said.
The American Beverage Association, an industry group, disputed the study, pointing out several limitations including that the researchers did not factor in kids' overall dietary habits or show a cause-and-effect relationship between sugary drink consumption and obesity.
"It is misleading to suggest that beverage consumption is uniquely responsible for weight gain among this group of children, especially at a time in their lives when they would normally gain weight and grow," said the ABA.