ADV36: Yes, a Virus Can Cause Obesity

A good friend once told us, “Obesity is not a disease. You can’t catch it.” We won’t deny that his comment reflects the feelings of many people. But on the facts, he was simply wrong. A new systematic review in the International Journal of Obesity tells us that, indeed, it is possible to catch obesity. Specifically, ADV36 (short for adenovirus 36) can cause obesity.

Adenoviruses spread through contact with droplets from the nose and throat of an infected person. Sound familiar?

Infected Animals Develop Obesity, Most Humans with Obesity Have the Virus

How can we be sure that ADV36 is responsible for obesity in humans? Of course, we cannot. And clearly, it is not responsible for all of the obesity that people experience. Many factors contribute to obesity. ADV36 is merely one of them. But it’s not trivial.

The study in IJO integrates the findings from 37 studies, with 10,300 adults and 4,585 young persons. Of those studies, 31 of them found an association between ADV36 infection and obesity. Four found no association and one did not describe the relationship. One study found an inverse relationship. The authors conclude:

“Although experimental infection of animals has facilitated the understanding of the adipogenic effects of Adv36, intentional human exposure to the virus is not possible due to ethical restraints. Therefore, the evidence for Adv36 as an etiology of human obesity depends basically on observational studies.

“Given the multifactorial condition of human obesity, it is hard to control bias when measuring the impact of each Adenovirus 36 prevalence and association with human obesity: a systematic review factor. In the reviewed studies, there was a high prevalence of Adv36 in all age groups, which exceeded 64% among adults and 73% among children and adolescents with obesity and/or metabolic disorders.”

In other words, this is likely as close to a smoking gun as we’ll ever get.

One of Many Causes

This research is a reminder that obesity has many causes. While it is certainly true that every one of us makes bad choices that affect our health, bad behavior is not obesity’s primary cause. Genetic susceptibility, combined with environmental triggers, explains most of it. ADV36 can be one of those triggers. Behaviors can make it better or worse.

The sooner everyone comes to grips with this basic fact, the sooner we can get past the bias and stigma that prevents progress in dealing with obesity.

Click here for the systematic review in the IJO. For an excellent perspective on challenging common assumptions about obesity and its causes, click here.

Nose It All, photograph © Gary Millar / flickr

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April 3, 2021