If the people you associate with are obese, chances are, there's a good likelihood you will be too, if you aren't already, according to a study (PDF) by a team of economists.

Why is that? According to the researchers, because of "imitative obesity." In other words, one gets fat in the presence of other fat people because it makes one feel good looking just like the other people.

The solution? Yes, exercise, but in order to change the mindset, associate with skinnier people.