A new study in mice shows that obesity might just be an infectious disease according to a study by researcher Richard Flavell, a professor of immunobiology at Yale School of Medicine.
In the study, mice engineered to have a particular immune deficiency developed fatty liver disease and got fatter when fed a Western-style diet. Fatty liver can cause inflammation and scarring. (Some fatty livers are also caused by excessive alcohol intake.) But strikingly, when these immune-deficient mice were put in the same cage as healthy mice, the healthy mice started to come down with symptoms of liver disease, and also got fatter.
We normally live in symbiosis with the bacteria in our guts, but in the study, the number of “bad,” disease-associated bacteria increased 1,000-fold in mice with immune problems, Flavell said. And it’s these bad bacteria that were transmitted from mouse to mouse, causing the healthy mice to also experience changes in their gut microbes and making them fat. It is more likely to be contagious in mice because they eat each others poop.
Fatty liver disease is very common among obese people, affecting 75%-100% of the obese population, the researchers say. In about 20 percent of these individuals, the disease progresses and becomes severe.
Previously, if two family members living in the same household both developed liver disease or became obese, people would have blamed genetics. Or could it also be the lifestyle of that household? Unhealthy food, fatty foods and lack of exercise could also be blamed. But the new study suggests the environment may play a role in this too. Perhaps antibiotics or probiotics could play an important role in the reduction of obesity.
Do you think you can “catch” obesity from a friend or family member?
The study was published online Feb. 1 in the Journal Nature.