The term "fat virus" represents the concept that people who are overweight have a virus that is responsible for their condition.
There are many well known causes for weight gain and obesity, such as overeating, genetics, a sedentary lifestyle, and psychiatric illness. The idea that weight gain and obesity are the result of an infectious agent, however, is relatively new and still hypothetical.
There are no published studies that show a definitive correlation between viruses, bacteria or other pathogens and increased body fat in humans. Several studies have shown, however, a correlation between particular viruses and increased body fat in animals. It is these studies with animals that lead scientists to believe that people who are overweight may have the fat virus.
Should a causal link be establish between a virus and human body fat, it has the potential to radically alter the entire weight loss industry, medical treatments, and public perceptions of people who are overweight. For one thing, it means that an "obesity vaccine" may be developed to help manage body weight.
Other terms commonly associated with weight gain of infectious origin include "obesity virus", "fat bug", and "infectobesity".
Human adenovirus 36 (AD-36) has been shown to cause weight gain in monkeys, mice and chickens.
AD-36 is one of 57 recognized adenoviruses, which are viruses in humans usually responsible for "common colds", pneumonia, bronchitis and other upper respiratory infections. They are also associated with gastrointestinal and eye infections.
Studies show that animals injected with AD-36 experience fat accumulation as a result. Scientists believe AD-36 may also be responsible for weight gain in humans.
Scientists do not test humans by infecting them with the virus because such testing would be contrary to ethical behavior. Therefore, humans are tested for anti-bodies to AD-36. The presence of anti-bodies is evidence that the virus exists—or once existed—in the body. Scientists also continue direct tests on animals with similar physiologies and anatomies to humans, such as mice and monkeys.
Research suggests that AD-36 anti-bodies are more commonly present in obese people than non-obese people. In a study of 502 individuals, researchers found that 30% from the obese group had the AD-36 anti-body versus 11% from the lean group.
AD-36 works by attacking the lungs and then spreading throughout the body. It spreads to the kidneys, liver, brain and even to fat tissue. When the virus comes in contact with fat cells, it is believed that it quickly replicates, creating new fat cells. The exact way AD-36 increases body fat in animals or humans has not been established.
Research has also shown that human adult stem cells, when exposed to the virus, develop into fat cells. Stem cells are essentially "blank canvass" cells, which can become any specialized cell in the body, such as blood cells, brain cells or fat cells. The virus seems to re-direct the stem cell from whatever specialized cell it was going to become, to a fat cell.
AD-36 has been known to transmit from animal to animal. How it transmits among humans is uncertain although many adenoviruses are transmitted through the air.
Junk Science Allegations
It is important to note that, despite the studies published on the subject, there remain serious questions and doubts about the existence of the fat virus.
Does the virus cause weight gain or are obese people just more likely to contract the virus? Do AD-36 anti-bodies linger in obese people for longer periods than in non-obese people? Since at least one study tested people at only one point in time, how do we know whether these people contracted the virus before or after they gained weight?
At best, research has shown an association between particular viruses and fat accumulation. A causal link, however, has not been established.
Listed below are a few of her many indictments:
The AD-36 virus was selected randomly from a catalog.
The scientists credited with the "discovery" of the fat virus, Nikhil Dhurandhar, Ph.D. and Dr. Richard Atkinson, M.D., were looking for a human virus that would simulate the animal virus (SMAM-1) that had been proven to increase body fat in chickens. According to her report:
...they turned to a laboratory-supply company catalog and randomly chose one of the more than fifty human adenoviruses in the American Type Culture Collection virus bank. They ordered Ad-36.This virus proved to also increase body fat in chickens.
AD-36 is not unique.
Ms. Szwarc points out that AD-36 is not the only human adenovirus to cause weight gain in animals. She refers to a Dhurandar/Atkinson study where they admit that other human adenoviruses may have effects similar to AD-36 in animals. She quotes from their report:
...effects of the other 49 human adenoviruses on adiposity and serum lipids in vivo and on adipogenic potential in vitro have not been assessed.. Since the AD-36/animal fat correlation was established, other scientists have found that AD-37 and AD-5 also increases body fat in animals.
The original study suggesting the existence of the fat virus in humans has never been replicated.
Ms. Szwarc says in her report:
The only published study to date linking the "fat virus," AD-36, to people was first described and presented as an abstract to IASO members in 1998, entitled "Evidence for an association of an obesity virus with human obesity at three sites in the United States."
This study remains the only study of AD-36 in humans and is the study being used to support the entire promotion of the human "obesity virus" and the antibody tests for it. This study wasn't published until March, 2005.
Beyond this one study, there have been no other published studies suggesting a link between AD-36 and human body fat. No other scientists have replicated the findings.Ms. Szwarc adds:
It's impossible not to notice that all of the articles about infectious obesity and an Ad-36 "obesity virus" have originated from Dhurandhar and Atkinson.
There continues to be no clinical trials registered at clinicaltrials.gov involving [Atkinson's AD-36 testing company] Obetech, Atkinson or Dhurandhar, Ad-36 or an obesity assay screening test.
Adenoviruses are common in Asian countries, which have low rates of obesity.
In her report, Ms. Szwarc quotes doctors at the University of Pittsburg:
Adenoviral infections are endemic in Japan, China and Korea, they wrote. These countries are not hotbeds of obesity, either, with China's rate at 3% and Japan's at 3.4%.
To read Ms. Szwarc's full report visit Obesity virus – a new risk factor?.
- Infectobesity: Obesity of Infectious Origin, Nikhil V. Dhurandhar, Ph.D., Published in The Journal of Nutrition
- Adenovirus 36 and Obesity in Children and Adolescents, Charles Gabbert, M.D., Michael Donohue, Ph.D., John Arnold, M.D., Jeffrey B. Schwimmer, M.D., Published in The Journal of American Academy of Pediatrics
- Fat Factors, New York Times Magazine
- Virus 'link' to childhood obesity, BBC News
- Can a common virus make you fat?, BBC News
- Obesity Virus, Fat Chickens and Life's Mysteries, Miller-McCune
- Too fat? Common virus may be to blame: study, Reuters