GlutenDude

I've done several 24 hour fasts with water only...they get much easier as you do them. And I've done one three day fast, but had the occasional carrot juice. I'm sure you can go longer, but I maxed out at three days.

My reaction time is 48 hours so I always go back two days to see what I ate. Sometimes I find the culprit...sometimes I don't.

Exhaustion is my biggest symptom by far. I have days where I take three naps. Have you gone dairy free? It took me years to feel better and it really started to kick in when I dropped dairy as well.