I have done 5 Liver Flushes on adrenal fatigue. I DON'T drink tons of juice before flushing, but I do drink the apple juice with the Epsom Salts as it is the only way I can tolerate the taste. And of course I drink the grapefruit juice with the olive oil. I haven't had any problems. In the end, the benefits of the Liver Flush outweigh risk of drinking the juice.
I definitely would NOT fast at all with adrenal fatigue.