Can Viruses Cause Obesity?

Is it possible that viruses can cause obesity? I'm not talking here about what we consider common viruses like the cold virus or HIV virus that attack humans directly, but bacteriophages, which attack bacteria and can kill them.

In fact, some people are using bacteriophages, often called just phages, to treat antibiotic-resistant bacterial infections. Phages were discovered in 1915 by FW Twort in England and then in 1917 by the Canadian Félix d’Herelle but haven't been studied a lot since then in terms of human disease.

Now there is some evidence that phages in the gut can contribute to obesity.

The idea that the gut microbiome can contribute to obesity is not new. Numerous studies have shown that transferring a sample of gut bacteria from fat animals into the guts of animals raised in sterile environments will produce fat animals, and transferring bacteria from thin animals will produce thin animals.

So it was not a surprise when University of Iowa scientists showed that the weight gain that often results from use of the drug risperidone, used for psychiatric disorders, was related to the gut microbiome of mice. What is interesting is that the researchers were able to cause the weight gain not just by transferring samples of the gut microbiota, but also by transferring the gut phages alone. When they gave the mice samples of isolated phages, the mice had decreased energy expenditure and a significant increase in weight, just as they had with the drug risperidone.

The usual caveat applies. Humans don't always react like mice. For one thing, humans don't set up  housekeeping in my walls. But our physiology is also somewhat different.

Nevertheless, the idea that bacteriophages could be affecting our weight is intriguing, and further research could lead to new approaches to keeping us all thin.