Obesity News
Childhood Obesity Blamed on Virus
By Christopher Wanjek, LiveScience’s Bad Medicine Columnist
Doctors have found more evidence that a viral infection can trigger obesity. And no, the virus doesn’t live on cheese puffs and Twinkies.
Researchers at the University of California, San Diego, found traces of adenovirus 36 (AD36) in an alarming number of obese children and went so far as to claim that there is a positive association between the presence of the virus and obesity, as reported this week in the journal Pediatrics.
Excess calories and inactivity are clearly associated with obesity. And yet some children who have junk-food-filled diets and an exercise routine comprising entirely of walking back and forth from the refrigerator and sofa do manage to remain relatively thin. Why?
In my blood
Genetics, a popular rationale for all that’s right or wrong with any given person, can’t explain all cases of obesity, doctors say, particularly the sharp rise in childhood obesity. Bad habits among children have remained constant over the last two decades, but the child obesity rate has nearly tripled during this time.
AD36 is one of dozens of adenoviruses that are common causes of respiratory infections. Studies dating back to the 1990s have shown that lab animals deliberately infected with this human virus can get fat. In recent years, other studies have shown that upwards of 30 percent of obese adults have been infected by AD36, compared with only 10 percent of normal-weight individuals. The theory is that the virus targets immature fat cells and gets them to mature and proliferate rapidly.
This latest UC San Diego study, led by Jeffrey Schwimmer, examined 124 children; slightly over half were obese. Among all the children, only 19 (or about 22 percent) had been infected with AD36, a fact determined by the presence of AD36-specific antibodies in their blood. But among these infected kids, nearly 80 percent were obese.
More surprising to Schwimmer’s team, the infected obese children were much heavier than the non-infected obese children. The average BMI of the obese kids was about 33; but among the infected obese kids, the average BMI was over 36.
This translates to an average, extra bulk of 35.5 pounds (16 kilograms) for those with the AD36 virus antibodies. That’s a huge amount of extra weight for adults, let alone kids. Sadly, most obese kids will be obese adults and have a lifespan shortened by up to 20 years. A study out this year suggested obese men could die eight years earlier than other men.
Fat chance
Clearly you don’t need a virus to get fat; bad food and eight hours of daily TV-watching can work well for you in that regard. But as skeptical as you (and I) might remain, some doctors are becoming increasingly convinced that AD36 is playing some role in the obesity epidemic. Schwimmer’s team indeed has upped the ante by finding that those once infected have a high probability of being even heavier than other obese individuals.
What Schwimmer and others haven’t been able to establish, though, is cause and effect. Is AD36 a cause of the weight gain, or is the infection the result of having certain kinds of fat cells that the virus happens to like? Or, are obese people predisposed to persistent AD36-specific antibodies after infection? That is, maybe most people have been infected, but obese people maintain the presence of antibodies longer.
So many unknowns. Makes you want to do something crazy like eat better and exercise, just in case.
Cold Virus Linked to Childhood Obesity?
I just read a new study that was published in the online version of the journal Pediatrics on September 20th that links childhood obesity to adenovirus 36 – one of the viruses that cause the common cold. Sounds crazy, right? Perhaps, but it does raise some interesting questions.
Researchers studied 124 children between the ages of 8 and 18. Fifty four percent (67) of the children were considered obese based on their body mass measurements. On average, children who tested positive for adenovirus 36 weighed about 50 pounds more than those who tested negative. And even among the obese children, those who tested positive weighed about 35 pounds more than the obese children who tested negative.
However, only about 15 percent of all of the children tested positive for the virus at all – 22% percent of obese children and 7% of children who were not obese.
So what does all of this mean?
At this point, it’s hard to say. There certainly isn’t enough evidence to say the virus causes obesity and the researchers don’t seem to be suggesting that either. However, there may be more to childhood obesity than just a lack of exercise and poor diet.
We all seem to be so quick to judge parents when it comes to obese children, but like most health problems, it is probably a more complicated issue.
On the flip side, this was a very small study that did not cover an accurate cross-sample of the population (67% of the children were hispanic, 27% white and 11% black) and only 15% of those (18 children) studied had ever had this virus. So drawing a conclusion that there is a link between the virus and obesity at all seems like a stretch. It’s almost like saying a majority of the obese children had brown hair so brown hair must be related to obesity – which of course is ridiculous.
In reality, it could even mean that children who are obese are more likely to get adenovirus 36. To me, this actually makes more sense, because people who are obese typically have weaker immune systems and get sick more often.
What do you think? Share your thoughts on this new study and read more about it from Catherine Holecko, About.com’s Guide to Family Fitness.