My dietician gave me a leaflet on this. Here is how it defines both:
Emotional hunger (head hunger):
1) is sudden
2) is for a specific food
3) is above the neck (in the mouth and mind)
4) is urgent
5) is paired with an upsetting emotion
6) involves automatic or absent-minded eating
7) does not notice or stop eating in response to fullness
8) feels guilty about eating
Physical hunger (true hunger):
1) is gradual
2) is open to different foods
3) is based in the stomach
4) is patient
5) occurs out of physical need
6) involves deliberate choices and awareness of the eating
7) stops when full
8) realizes eating is necessary
So basically, true hunger comes on over a period of time and you will have growling and feelings in your stomach area. Head hunger is more immediate!
Hope that helps

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