Think again before you dive into a plate of French fries with your friends or go on a reality TV binge with your buddies. Researchers from Arizona State University's School of Human Evolution and Social Change have found that having fat friends normalizes being overweight and overeating and can make one more prone to being obese and inactive. Here, a brief instant guide:

What did the study find?
In short, the fatter a woman's friends, the more likely she was to be overweight or obese. (The study looked specifically at women and their closest friends and family members of unspecified gender.) On a subliminal level, having portly friends can make unhealthy eating patterns seem "normal" and subject you to pressure to work out less. Additionally, social activities with obese friends is more likely to center around eating or sedentary activities like television-watching, which can lead to weight gain. "You may form an idea of appropriate body size by simply observing your friends' bodies, which in turn changes your eating and exercise habits," says lead author Daniel Hruschka.

How was the study conducted?
Researchers interviewed 101 Phoenix, Ariz. women and 812 of their close friends and relatives. They looked at the Body Mass Index (BMI) of the women and those in their social network.

Have there been studies like this before?
Yes, a 2007 study out of Harvard Medical School also found that a tendency towards obesity could be transmitted, in a sense, among friends.

What are the implications of the findings?
The study's authors say it offers "important clues," for fighting obesity. "If we can figure out exactly why obesity spreads among friends and family members, that can tell us where to focus resources in curbing rates of obesity," says Hruschka.

Sources: Telegraph, New York Times, Third Age, News Medical