My wild ass guess is one month.

I base this number on marijuana testing supposedly useless after a month. It does work very well for two weeks though because some byproduct is fat soluble and is absorbed by your fat cells where it takes them up to a month to completely rinse out. So, for example if you were eating a lot of high hormone ranch animal meat there may well be junk in there that takes your system a month to completely purge it out after you stop eating the high hormone ranch animal meat and you would not be able to see the effects undiluted for a month. Also this is the time granule I use for my own diet self-experiments which I seem to never get to the end of. My diets are for fitness and health purposes only as I have never been much over- or underweight.