Jonathan Zimmerman is a Narberth resident and a professor of history at New York University. He is teaching a course at NYU's Abu Dhabi campus. E-mail: jlzimm@aol.com.

...In Washington, stricter regulation of video games has become a post-Sandy Hook cause du jour. Last week, Vice President Biden convened a high-profile meeting with video-game executives. Some have called for warning labels and other precautions.

But we still don't know if playing video games makes users more likely to behave aggressively. Research on the subject is spotty and mixed, and millions of Americans clearly play violent games without becoming violent.

For the most part, they also play them in a stationary position. So we shouldn't be surprised that video games are very strongly associated with obesity, especially among the young. In 2011, the World Health Organization named video games the single biggest cause of child obesity.

Why would playing video games lead to more weight gain than, say, watching television? Nobody knows, although one recent study suggested an intriguing possibility: Video games make you hungry. Boys who played them were found to consume four times as many calories as they burned off....