Obvious example: Monks practice self mutilation (flagellation) to rid themselves of "spiritual impurity", whereas an ED sufferer could practice purging or restriction among other things to achieve the same goal of "purity". Depending on context, the same behaviour, with the same goal, can be defined as 'devout' or 'crazy.' (I won't add my personal opinion on whether or not those terms should be divorced from each other ;)
I'd appreciate any input/personal experiences with this concept.
(Posted to http://community.livejournal.com/ed_philosophy/