A long time ago I did a fast. I was 11 stone I got down to 9.2 stone (sorry I don't know the US mesurements).

It's a mistake to fast while there's mercury in the body. Mercury attaches itself to muscles and if you have less muscle you'll feel the mercury poisoning more.

However, I did this to see what foods affected me. I found that tap water (mineral was fine) affected me the most. To such an extent I ached so much and my brain was so dead I just had to lie in bed. I couldn't do anything. Even brita water filtered affected me as it's filtered with a tiny WHO-safe amount of mercury (I'm sure it's fine for most people but when you've hardly got any muscle and there's already a lot of mercury in your body it does).

I also found that the raw fish I was eating affected me. Actually, somedays it was fine, others it was not. This I eventually accounted to the occasional mercury that fish contain due to pollution.

Realising these two things convinced me about the mercury poisoning.