Can a virus cause childhood obesity? It just might, according to a new study. Researchers found that a virus that causes the common cold, adenovirus 36, is strongly linked to obesity in children. Adenoviruses usually lead to upper respiratory tract infections and enteritis (gastric upset).
The researchers followed 124 children between the ages of 8 and 18. Fifty-four percent of the kids were considered obese, based on their body mass indices (BMI). The researchers analyzed the antibodies in the children’s blood to see what kinds of viruses they’d been exposed to in their lives.
Because of the study’s design, it is impossible to tell whether AD36 causes obesity or whether there’s a different connection — for example, whether being obese makes kids more susceptible to the virus.
They found that 22% of the obese children had antibodies for adenovirus 36 (AD36) in their blood, while only 4% of the non-obese children did. Kids who had the antibodies had higher BMIs, and they weighed significantly more; they also had larger waists and higher waist-to-height ratios.
Though the mechanism is still somewhat unclear, Charles Gabbert and his team from Rady’s Children’s Hospital in San Francisco write that earlier animal studies have found the same connection between adenoviruses and obesity. There is some evidence that the metabolism of fatty acids is impaired after infection with the virus, and that the way that glucose and leptin function is altered (leptin is responsible for people feeling full after meals).
Because of the study’s design, it is impossible to tell whether AD36 causes obesity or whether there’s a different connection — for example, whether being obese in the first place makes kids more susceptible to the virus. The team writes that "[i]f causality is established, it would have considerable implications for the prevention and management of childhood obesity."
Since being obese has so many negative implications in a child’s life, the idea of a virus playing a role in obesity might help to change society’s perception of obesity per se: "The possibility that excess weight gain in some children may be attributable to a viral infection could alter the public debate and perceptions regarding childhood obesity". The next step will be to learn more about the connection (for instance, whether causality is at play), and to determine whether children who have been exposed to the virus respond to weight reduction treatments in the same way as those who have not.