Controversial Health Topic: Obesity Is Caused by a Virus

One of six medical theories on the verge of going mainstream.

Inspiration first struck obesity researcher Nik Dhurandhar at a dinner party in Mumbai, India, 25 years ago. “I was speaking with a veterinarian who was an old family friend when he mentioned that thousands of chickens that had died from a virus had gotten very fat,” recalls Dhurandhar. “I said, Wait a minute. You’d think a dying chicken would waste away, not the opposite. My mind began to spin. Was it possible somehow that both conditions were related?”

Dhurandhar continued studying the phenomenon. He soon realized that animals infected with the common cold virus AD-36 gained weight. When he tested his theory on more than 500 people, he found that 30 percent of the obese subjects tested had been exposed to the AD-36 virus compared with only 11 percent of lean individuals. Since then, follow-up studies by other researchers have produced similar findings.

“We think the virus infects fat cells, causing them to divide and grow faster than normal,” explains Dhurandhar. The silver lining: The virus appears to improve blood-cholesterol and blood-sugar levels. “Your body may produce more fat cells, but that means there’s less fat left to travel to your liver and blood,” says Dhurandhar. This may help explain why some overweight people are less likely to have heart disease or diabetes than their thinner counterparts. While Dhurandhar acknowledges that the virus isn’t the sole cause of obesity, it may explain why some people struggle to lose pounds. “If you do have the obesity virus, it doesn’t mean you’re incapable of losing weight—it just means you’ll have to work a lot harder,” he explains.

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Over the next decade, researchers hope an obesity vaccine will become available to inoculate people against AD-36. (Researchers are also working to identify other viruses tied to obesity in humans.) There’s no reason to get tested to determine if you have been exposed to the virus; since about half of obese people haven’t, it’s clear that other factors, such as lifestyle and genetics, play a bigger role.

Adam Voorhes

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Originally Published in Reader's Digest