08 September 2008

Obesity may be caused by a virus

Could obesity be caused by a virus? And, if so, could researchers find an obesity cure based on a vaccine? DietDoc investigates.

Could obesity be caused by a virus? And, if so, could researchers find an obesity cure based on a vaccine?

These are not flights of fancy or pipe dreams, but relevant questions based on the findings of an American study (2005) which showed that up to 30% of obese test subjects were infected with Adenovirus-36 (Ad-36).

“Infectobesity” is the new term researchers have coined to describe the type of obesity that's linked to Ad-36 infection.

According to Dr Richard Atkinson, the Director of the Obetech Obesity Research Centre in Virginia, USA, it's important that the public and the medical profession should be aware of the fact that not all cases of obesity or overweight are due to "lack of willpower or overeating".

Now that Ad-36 has been identified and its link to obesity has been established, obese people should be tested. The reason, as Dr Atkinson states, is that “it's much easier to prevent obesity than it is to treat it”.

The expert goes on to explain that when fat cells grow and reach a specific size, they start producing chemicals that stimulate the formation of new fat cells, which then starts the vicious cycle of ever-increasing obesity (Obetech, 2008).

He is of the opinion that if an individual knows that he or she has been infected with Ad-36, they can take precautions not to gain weight in the first place and thereby prevent the development of obesity.

Dr Atkinson also advises that any person who suddenly starts to gain weight for no good reason can benefit by being tested for Ad-36 antibodies before his or her weight gain spirals out of control. Considering that there is a 60% to 100% risk of developing obesity if you have been infected with Ad-36, testing is also important for people who are not yet obese.

Public testing now possible
In 1997, Dr Atkinson and Dr Nikhil Dhurandhar founded the Obetech Obesity Research Centre in Virginia to study Ad-36 and to try and develop the necessary technology to combat this virus.

This Research Centre offers the American public testing to determine if individuals have been exposed to Ad-36. Visit their Website at to read more about Ad-36 tests.

Although these tests appear to only be available to the American public, it's possible that the Research Centre may also offer such tests to people in other countries.

Positive test - now what?
Dr Atkinson recommends that anyone who has tested positive for Ad-36 should contact their medical doctor (and dietician) for assistance in losing weight if they're already on their way to becoming obese.

An energy-restricted diet rich in fruit and vegetables and increased levels of physical activity – that's 30-90 minutes of vigorous activity (brisk walking, swimming, cycling, skipping or doing an aerobic gym workout) for five or more days a week – is generally recommended.

People who are already morbidly obese, can benefit from medications like Xenical. In extreme cases, bariatric surgery is indicated.

AD-36 suppresses leptin
The latest scientific publications in this field include a study conducted at the Department of Human Nutrition & Food Science at Wayne State University in the USA.

A team led by Dr Vangipuram (2007) used ‘young’ fat cells and infected them with a variety of adenoviruses. They found that Ad-36 suppressed the production of leptin by up to 51% in fat cells infected with this virus, while fat accumulation in these cells was significantly higher than in cells that had not been infected. In addition, the fat cells also had an increased uptake of glucose which would also simulate fat production.

Another study, this one with human stem cells obtained from body fat, was performed by Dr Pasarica and coworkers (2008) at Pennington Biomedical Research Centre in Louisiana. The researchers found that stem cells are stimulated by Ad-36 to develop into adipose (fat) cells, thus contributing to the tendency of humans to develop obesity.

Where to from here?
Dr Atkinson and his team are doing research “to determine if certain types of drugs may be used to produce weight loss in overweight and obese people who test positive, and to prevent weight gain in all Ad-36-positive individuals”.

A vaccine to prevent obesity may also be in the pipeline, but such a new product would need to be extensively tested and this will take time.

(Dr I.V. van Heerden, DietDoc, updated September 2008)

(Atkinson, R, Dhurandhar, NV (2008). Obetech, LLC. Answering questions about obesity. ; Pasarica M et al (2008). Adipogenic human adenovirus Ad-36 induces commitment, differentiation, and lipid accumulation in human adipose-derived stem cells. Stem Cells, 26(4):969-78; Vangipuram SD et al (2007). Adipogenic human adenovirus-36 reduces leptin expression and secretion and increases glucose uptake by fat cells. Int J Obes (Lond), 31(1):87-96.)

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