Is Obesity Catching?

In the modern, appearance-obsessed world, being fat is associated with gluttony and laziness, even though many overweight people protest that diets don’t work for them. A new field of study contends that there may indeed be a viral component in some cases of obesity.

In 1994, Nikhil Dhurandhar was hired by Richard Atkinson, whose 30-plus years in the field of clinical research earned him a reputation as an expert on obesity, to investigate the effects of a common virus in humans.

A decade later, from his lab at Pennington Biomedical Research in Louisiana, Dhurandhar launched the theory of “infectobesity” – that the cause of obesity may be linked to one of the million microbes in the human body. By 2006, scientists all over the world were hard at work trying to find a connection between obesity and viral components.

Let’s get the bare basics on the theory, and the medical community’s less than welcoming reaction to it.

Infectobesity

… is a term coined by Dhurandhar while he was researching the relationship between obesity and viruses. In the 1970s, millions of commercially raised chickens in India died from a virus called SMAM-1. In 1988, Dhurandhar, then doing his doctorate at the University of Bombay, conducted a small experiment involving 100 chickens. He discovered that injecting the chickens with SMAM-1 caused enlargement of their livers and kidneys. He also found excess fat in the abdominal area.

Thus his new theory was born: Any ordinary virus inside the intestines of a living organism may cause weight gain and excess fat storage.

SMAM-1

… is a poultry virus known to cause obesity in chickens, which leads to an alarming death rate. Dhurandhar wanted to determine if the same virus could affect humans. In the early 1990s, he tested the blood samples of 52 overweight patients. Twenty percent of the patients who had been infected with the virus had gained 33 extra pounds, albeit with a lower level of cholesterol and triglyceride, compared with those who were not exposed to the virus – a similar result to that found in chickens.

“The findings violated conventional wisdom,” Dhurandhar was quoted as saying in a 2006 New York Times article titled “Fat Factors”. “The first is that viruses don’t cause obesity. The second is that obesity leads to high cholesterol and triglycerides. The third is that avian viruses don’t infect humans.”

In 1994, Atkinson and Dhurandhar wanted to do further research using samples of SMAM-1, which had to be imported from India. Unable to bring the virus samples across the border, they found a virus with similar traits to SMAM-1: human adenovirus.

Adenovirus (Ad-36)

… is a common virus that exists in the human body and may cause problems so mild we usually don’t realize we’ve been infected. Atkinson’s and Dhurandhar’s research team managed to gather 502 volunteers from all over the continent. Atkinson’s approach was to screen the amount of the adenovirus’ antibody in each volunteer’s body (an antibody is usually developed once the body has been infected by a certain virus).

Atkinson and Dhurandhar discovered 11 percent of the leaner patients had been previously infected by Ad-36, while 30 percent of the obese patients had been infected at some point in their lives. Not a coincidence, according to Atkinson, if we look at the gap between those statistics.

“The cause of obesity is not a secret – if you consume more calories than you burn in daily activity, you gain weight. What is interesting is that much of the obesity epidemic cannot be explained just by (our tendency) to eat more and exercise less,” Atkinson told Medical News Today. “There are other factors at play, and viruses causing obesity may be one of them.”

The X Factor

… was, is, and – probably for quite some time – will be that we are eating too much and exercising too little. Atkinson and Dhurandhar face public health officials and medical experts in the field who denounce infectobesity as something coincidental or, worse, imaginary. Stephen Bloom, a scientist based in London, is particularly scathing about the theory. In an interview with the Journal of Medical Association, he openly joked that he preferred to call the X Factor the “lazy, greedy gene” as opposed to microflora or adenovirus. “I don’t think we need that [infectobesity] explanation,” he was quoted as saying by The New York Times. “Since we have a perfectly good other explanation.”

It’s a Long Road Home

… for Atkinson and Dhurandhar, with the scientific community not convinced, despite the efforts the two have made to try to find the causes of obesity. Atkinson says that it may take at least five years for anyone to come up with a vaccine if adenovirus is, indeed, proved to cause the epidemic. But that’s no reason for him or Dhurandhar to back down.

“It may or may not be the thing we’re looking for,” Atkinson has been quoted as saying. “But, at least, we’ll know that we’ve tried our best.”

+ Maggie Tiojakin

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