This was prompted by my niece asking for advice about a workshop she was going to give. At first the workshop was supposed to be on fat acceptance, but then they changed it to be on body acceptance.
The thing is, these are two very different subjects. Body acceptance has to do with your own perception of your body and whether or not that perception is realistic.
Fat acceptance, on one level is body acceptance, except you are (most often) also dealing with society’s perception of your body.
Changing your own perception of your body can be a lot of work, but it is something you have control over and you can change. Changing the perception of society is something you can work on, but it is, on the whole, beyond your ability to change. Yes, you can work on changing your personal environment and the people you deal with and try to educate them about fat acceptance. But for the most part, this is something that is beyond your control — all you can control is how you, personally, deal with it.
Body acceptance may or may not have anything to do with other people. Fat acceptance has a lot to do with other people.
Both are important issues, but they are not interchangeable; and I think that people need to realize the difference.