On one web site, fat was defined as, “A natural oily or greasy substance occurring in animal bodies, esp. when deposited as a layer under the skin or around certain organs.” Okay, not so bad.
On dictionary.com, it reads, “having too much flabby tissue; corpulent; obese: a fat person.” Well, this one may upset some people.
So, the bottom line to me, it is how the term fat is used. I guess sometimes used in scientific descriptions, it is okay to use the word fat. In describing a person, it may not be the best word to use, as it could be derogatory. When it comes to children, the media has to be real careful with their wording!
What is your opinion?