Setbacks and Stumbling Blocks:

Slip: A slip is a thought- but not an action- related to the eating disorder.

Lapse: A lapse is more serious than a slip in that it moves beyond obsessive thoughts and back into the eating disorder behavior, but in a limited way. Although a lapse means the eating disorder behavior has become active again, the experience is brief.

Relapse: Far more serious, a relapse involves recycling the same eating disorder behavior that brought the person into treatment. A relapse means the behavior has returned on a regular basis, not just as an episode. It may even return to full intensity.  

Collapse: A collapse is the full-blow return of the original eating disorder behavior. An untreated relapse can turn into a collapse, and an untreated collapse can turn into an even more intense form of illness, to the point that intervention and possible hospitalization become necessary.