I don't know what "DANDR" is, but according to Atkin's second edition, your friend needs stay on the Fat Fast only two days to determine whether he goes into ketosis. Atkins says that you do it after Induction, but I think you could do it anytime.

Can your friend stomach cream cheese and macadamias for two days? Or any of the other things he doesn't like?

I am going to try this Fat Fast next week when everybody's gone on vacation and I don't have to try to cook double or eat out. I have never seen the Ketostix turn a nice purple, and I want to see that!