Increasing digestive fire

I probably have the opposite problem of most people on here. But I thought I'd ask everyone anyhow.

My problem is this: I never get hungry.

Some of the reasons are that I was a raw vegan for 2 years which dampens digestive ability. Also, I have always been a little underweight and perhaps genetics plays a part in my weak constitution.

I can literally go for 3 or 4 days eating very little or nothing - and not get hungry. I know I have a seriously weakened liver and am already doing things to help that, like occasional liver flushes.

Anyhow, my question is whether anyone has any advanced or unusual tips for increasing digestive fire?

I am already doing a lot of the recommended things: eating ginger, avoiding bad food combining, eating small meals, not eating late, eating whole foods, taking liver herbs, etc.

Now when I say I don't get hungry I don't mean that I don't have an appetite. The opposite really. I have to hold back and not eat too much food or my digestion will come to a standstill.

The only thing that I have found to work is that if I eat certain types of fish or salads for each meal, that then I will get actual hunger before the next meal.

I used to do fasting, and I don't think it works for me. It just weakens me. It puts my fire out completely so to speak. Where as I need to gently stoke it.

Anyhow, any tips?