True Hunger question

I am on day 18 of my water fast. I'm not sure I have any fat left.

I had a terrible time until a couple of days ago with nausea, dry retching, feeling bad, weakness and having to stop work in the afternoon.

I *guess* I got rid of the horrible toxins in my body and this is why I started to feel better.

Yesterday, slowly I developed a hunger which seems to be in the top of my chest. Since this morning (6 hours), it became constant.

I don't know how much of what is described for Water Fasting varies by individual. So I wonder if this is "true hunger."

I am a lot more mentally alert today than I have been during the fast. My tongue is far more clear.

What is the actual evidence that true hunger takes place when toxins are gone vs this is something that you experience when your fat is burned up?