Can behavior such as Couch’s spread from one person to another? There’s some evidence that it can: A 2010 study found that the level of self-control demonstrated by people around you can influence your self-control in one direction or another. If you see people acting with little self-control, you’re less likely to exercise self-control, and vice versa, according to the study authors.

“The take-home message of this study is that picking social influences that are positive can improve your self-control,” said lead author Michelle vanDellen, a psychology professor at the University of Georgia. “And by exhibiting self-control, you’re helping others around you do the same.”

And an earlier study, published in 2007, found that obesity is “socially contagious” — people with friends who become obese over time are 57 percent more likely to become obese themselves.