A common virus may be one of the causes of the troubling obesity epidemic in American children, a new study shows.
University of California, San Diego researchers found that obese children were far more likely to have antibodies to a specific strain of adenovirus than normal weight children, according to the report published early online in Pediatrics. Children who showed signs of infection with adenovirus 36 (AD36), a common cause of some colds and eye infections, were an average of 50 pounds heavier than those who had no antibodies to the virus.
“This shows that body weight regulation and the development of obesity are very complicated issues,” said the study’s senior author, Dr. Jeffrey Schwimmer, an associate professor of pediatrics at UC San Diego and director of Weight and Wellness at Rady Children’s Hospital in San Diego. “It’s not simply a case that some children eat too much and others don’t. There are children who eat all the wrong things in all the wrong quantities who are not obese.”
Outside experts cautioned that the new research doesn’t prove that the virus causes weight gain — it’s entirely possible that obese kids are just more likely to get the virus.
Virus may rewire fat cells
Still, earlier research with cells in petri dishes suggests that the virus may cause changes in the body that lead to weight gain. Some studies have shown that the virus can enter fat cell precursors, rewiring them to spew out more fat cells, while others have shown that the virus can modify fat cells themselves so that they store more fat.
Other experiments have shown that animals have significant weight gain after researchers infect them with AD36.
Many Americans have had experience with adenoviruses, though they may not have known that this specific type of virus was what led to their symptoms. The viruses cause a variety of illnesses ranging from sore throats to diarrhea. AD36 is one of two that have been linked to obesity.
Schwimmer and his colleagues tested 124 children, ages 8 to 18, for antibodies to AD36. Slightly more than half of the children, 67, were obese, while the other 57 were normal weight.
Antibodies to AD36 were found in 15 of the obese children and 4 of those with normal weight. The virus appeared to have a particularly pronounced effect among the heavy children: those who were positive for AD36 weighed an average of 35 pounds more than other obese kids who didn't have the antibodies.
Schwimmer isn’t blaming all childhood obesity on the virus. Some kids just eat too much and exercise too little, he said. “But, I’ve seen children who had very brisk weight gain in a given year for reasons that were very hard to pinpoint,” he said. “These may be the children who have obesity related to this infection.”
Dr. James Cherry, a specialist in pediatric infectious diseases, was intrigued by the new study and suggested that if further studies prove that AD36 leads to weight gain, it might make sense to develop a vaccine to the virus.
“More than 20 percent of the obese children in this study were positive for the antibody,” said Cherry, a professor of pediatrics at the David Geffen School of Medicine at the University of California at Los Angeles. “If we could prevent 20 percent of all obesity, that would be pretty impressive.”
Parents should focus on exercise, diet
For now, though, parents will have to focus on dieting and exercise for controlling their children’s weight. There is no test for AD36 currently available to the general public, Cherry said.
And even if parents found out that their children had had the virus, they wouldn’t be able to do anything about it, said Dr. Goutham Rao, clinical director of the Weight Management and Wellness Center at the Children’s Hospital of Pittsburgh of the University of Pittsburgh Medical Center.
“Instead of coming to the doctor and requesting a test for the virus, parents would do better to discuss key behaviors to combat obesity,” he added.