New Theory on One Cause of Obesity

from Botton Line's Daily Health News

New Theory on Cause of Obesity

All is not fair in the obesity battle... some people gain weight easily and struggle to lose, while others who eat fairly freely and don't exercise much are able to maintain a trim figure. Though obesity is known to have multiple causes, researchers have tended to focus on the genetic and behavioral ones -- with good reason, as those usually are the culprits. But some scientists have set out in a new direction, thanks to research spanning 20 years that shows certain viruses may be associated with obesity. It's an intriguing story with some interesting twists and turns that pose an interesting question: What if catching a virus makes you more vulnerable to become obese?

ONCE UPON A TIME...

In 1988 Nikhil Dhurandhar, PhD, a biochemist and young physician in India, happened to be chatting with a fellow researcher about a virus that was killing chickens locally. Autopsies on the dead birds revealed, oddly, that the infected ones had excess abdominal fat. His curiosity piqued, Dr. Dhurandhar injected some healthy chickens with the virus, and they too grew chubby. On a hunch, Dr. Dhurandhar then examined human blood samples from a group of obese male and female patients for presence of the virus antibodies. Sure enough, he found that 20% of them had indeed been exposed to the virus. That percentage is not likely to be found by chance, so he hypothesized that there must be a connection. It was an important discovery for two reasons -- first, that the SMAM-1 avian virus was likely to have crossed over to humans, which had not been thought possible back then... and second, that there could be a viral connection to obesity.

MORE THAN ONE VILLAIN

Fast forward a few decades. Now an associate professor of infection and obesity at Pennington Biomedical Research Center in Louisiana, Dr. Dhurandhar has been fighting conventional wisdom in an attempt to pin down a pathogenic role in obesity -- with considerable success. While researchers have isolated 10 different pathogens that are linked to obesity in animals or humans, his research team is currently investigating one of them intensely.

But, he says, it's not the particular virus that is important, so much as the concept of what he calls "infectobesity." "It's the idea that obesity might be caused -- in some cases -- by an infectious origin. We're currently investigating only one of the obesity-causing viruses, but imagine how many might be out there awaiting discovery?" The virus Dr. Dhurandhar's team is working with is not an animal virus or pathogen, but a human adenovirus known as Adenovirus 36, or AD-36. In one study, the researchers have detected AD-36 antibodies in 30% of obese people -- and, interestingly, the antibodies were also present in 11% of non-obese people.

Conscious of, and careful about, our culture's inclination to seize on any newly discovered cause of obesity as "the general cause," Dr. Dhurandhar stresses that he's not suggesting a virus is at the root of all obesity. However, he notes, "an interesting fact is that the 11% exposed to the virus who are not obese are significantly heavier than the non-obese people who haven't been exposed. This 11% is not technically obese -- at least not yet -- but the fact that they're significantly heavier than those with no antibodies shows that exposure to the virus may be having an effect."

ALAS, NO MAGIC POTION

Dr. Dhurandhar warns that no one should be fooled into thinking a magic potion in the form of drugs or a pill to combat the problem will soon be available -- though he does hope to someday develop a vaccine to protect against this particular cause of obesity. "Some causes for obesity are genetic, some are absolutely due purely to overeating and inactivity -- and our research shows that there is a viral component that comes into play for at least a percentage of obese patients," he says.

Based on their studies, AD-36 increases the number of fat cells and the amount of fat stored in them, which possibly contributes to obesity. But, even as pathogens that contribute to obesity are identified and treatments become available to fight them, people will still need to take responsibility for eating right and exercising regularly. Because, regardless of the causes of obesity -- and it may turn out that there are far more than anyone ever suspected -- a poor diet and a sedentary lifestyle will only make things worse. "We're looking for more weapons to use in our fight against the obesity epidemic," said Dr. Dhurandhar. "But we still need to make use of the ones we already have -- and for now a good diet and exercise plan are among the best ways we know to not only maintain weight, but also to bolster the immune system to help fight viruses, even possibly the 'obesity one'.

Source(s):


Nikhil Dhurandhar, PhD, associate professor in the department of infection and obesity at Pennington Biomedical Research Center, Louisiana State University System. He and his research team have been at the forefront in the investigation of obesity of infectious origin.