Blame Your Friends For Making You Fat

Fat is contagious!

New research has come out that shows that the people you associate with have a big impact on your own body weight and fitness levels, as much as 40-70% percent.

This isn’t a case of people just associating with people who are similar to themselves – the study focused on Air Force academy undergrads who are randomly assigned to live with a group of 30 other people.

Interestingly the study found:

…that the peer effects work largely through exposure to the least fit peers, and the students most affected are those at the lower end of the fitness distribution. This asymmetry in the nature of the peer effects suggests that individuals appear to either compare their own fitness to the least fit among them, or adopt the diet and exercise of the least fit.

So, if you want to have the greatest effect on improving a group’s overall fitness levels, focus on improving the least fit first.

Is Poor Fitness Contagious? Evidence from Randomly Assigned Friends [The National Bureau of Economic Research]
Your Friends Are Making You Fat and Lazy [Economix]