Well, through dieting (and presumably ignoring hunger), you can certainly lose touch with your hunger signals. That makes it difficult to know when you are eating out of physical hunger or emotional hunger. You didn’t say whether or not you were a dieter, so for the purposes of this post, I’ll assume you have a history of dieting. If you have never known what hunger felt like, then it might be more complex and need to be addressed by a doctor.
Digestive issues, if you have them, can make it even worse. Now, I can’t tell you how you feel hunger, but it is physical. Sometimes, it’s a nagging feeling in the gut. You may be irritable or feel weak. Myself, I define the time to stop eating in a few ways. Lack of the hungry feeling, disinterest in the food (maybe I’ve slacked off from shoveling it into my face), or it could also be a more logical decision based on, say, “If I eat more, the heat will make me feel sick.”
If you are terrified (which you didn’t say you were) of gaining weight, it will be difficult, if not impossible for you to get in touch with your hunger signals. Because if you are coming off of dieting, you do need to let your body do some of the directing and not let your psyche interfere. And sometimes, you need to guess, but fine-tuning does come.
I would recommend that you start thinking about this with the book “Intuitive Eating” by Evelyn Tribole & Elyse Resch. This book does address intuitive eating from the perspective of coming off a dieting history, so it may not be for you.
Good luck! I will be interested to hear what others have to say in regard to the signals, especially those who have always been able to feel hunger/satiety.