> It can be good advice with additional conditions. For example I now eat whenever I feel hungry but only for the half of the time that I'm alive. For the other half I just don't eat at all. The only exception I make is for tea and occasional coffee with milk.

You're effectively saying "It's good advice if I ignore it half the time", with your positive outcome stemming from the time spent ignoring it and not eating altogether.

It's silly and harmful advice. Feelings are inherently irrational, we shouldn't advise people to act on them.

When it comes to diet, what you eat largely governs how it makes you feel. The "feeling hungry" part is emergent, root cause largely being the diet.