I think one reasonable solution to this is simply to offer her food on a reasonably regular basis, and allow her to eat however much she wishes at each meal (including none). Offer her breakfast, lunch, dinner, plus a snack in between each, say at 08:00 (breakfast), 10:00 (snack), 12:00 (lunch), 3:00 (snack), 5:00 (dinner). She'll be getting food often enough that she'll have the blood sugar and the necessary energy to get through the day, and she will have several opportunities to eat enough for her other needs.
As long as you're not pressuring her to eat a particular amount, this should work fairly well. It's important not to pressure her to eat though - not even the 'finish your plate, there are kids in China starving' or whatnot from our parents' era. Be accepting if she eats nothing at a meal or snack.
You can also separately work with her to understand her feelings. I work with my three year old to help realize when he's misbehaving because he's hungry or low blood sugar; I point it out to him that he is probably hungry based on his behavior, and he often agrees. Kids often need to be taught what certain feelings mean - just like they often need to be taught what it feels like when you need to urinate. When she seems to be hungry based on her mood, behavior, etc., plus a reasonably long time since last meal, point out to her that she is probably hungry. Over time she will learn to recognize it.