"Fat talk" is the discussion about body size, shape and weight, valuing the thin ideal.  It includes disparaging comments about one's own body and/or the bodies of others.  Some examples:

• "I look so huge in these pants."
• "My thighs are disgusting."
• "I need to lose 10 pounds." 
• "Did you notice how much weight she's gained?"
• "I can't wear that because I look fat in it." 
• "Look at how big [insert celebrity] has gotten."

Sadly, it has become a way that women relate to each other.  Sit in on any gathering of females and you're bound to hear fat talk.  You're also likely to hear which diets everyone is trying.  Frankly, what a boring topic of conversation.  Why can't women support each other around things that matter more than the size and shape of our bodies?  Because we have placed so much of our self worth on our size.   

A study recently published in the International Journal of Eating Disorders looked at the consequences of fat talk in friendship groups.  They paired up women randomly in groups where the friend expressed either fat talk, positive body talk or neutral talk.  The fat talk group experienced elevated levels of disordered eating.  Disordered eating is a known risk factor for eating disorders.  

Every time you participate in fat talk you are spreading the thin ideal like a virus.  You are also increasing the likelihood of disordered eating in both yourself and your friends.  Not cool.  Let's stop fat talk and find more interesting things to talk about. 

Source:

Cruwys et al. An Experimental Investigation of the Consequences and Social Functions of Fat Talk in Friendship Groups. Int J of ED. 2016;49:84-91.