Watch who you hang out with -- your friends might determine your weight.

Photo: freeparking, Flickr

That's according to studies from Duke University, which found that college students ate significantly less when they dined with someone overweight. Conversely, if they ate with someone thin, they tended to consume the same amount as their dining companion.

I'm not saying you should trade your current friends in for some chubby ones -- rather, just make sure you're always aware of your portion sizes and you're putting down your fork when you feel full.