I think that CR shares a lot with orthorexia, the difference between "being obsessed with being healthy" and "having a disorder consisting in being obsessed with being healthy" is, in my opinion, in the results: is the social life of this person damaged by his/her diet? Does he/she avoid friends to avoid eating with them? Is he/she going trhough a divorce caused by his/her low libido? Is the physical health of this person damaged by this strict diet? Is the mood of this person too low or irrationally high? Does he/she have other interests than CR? Can he/she take pleasure in other activities?
I also think we should ask ourselves "Why am I doing this?", "Am I using my diet as a substitute for something?", "What does it gives me that I feel lacking in my life?"
Almost everything can be done in a healthy way and for healthy reasons or in an unhealthy way and for unhealthy reasons.