You need to listen to your body, yes. But you also need to feed your body. Your body will give you signals when you are truly hungry. But if you ignore these signals THEY WILL GO AWAY. Your body is a calorie burning machine. If you only eat 500 calories, your body will adjust to burn less energy. Instead of burning 3000 calories, your body will conserve energy and burn only 1500 calories. 

I’m currently facing the same problem as you right now since I’ve switched my diet. It’s really hard for me to get even 1200 calories in most days if I’m just eating intuitively. I’m the girl who has always preached that no one should eat so little as 1200 calories, and here I am barely being able to do it myself recently. So honestly, I don’t know.

But the explanation above is the best advice someone else has given me when I asked about this problem. Yes you should only eat when you’re hungry, if your hunger signals are working properly. But you should also set yourself on a consistent eating cycle. And you still need to fuel your body. Your body cannot survive on 500 calories. So although you may not FEEL hungry (because perhaps your body told you you were hungry and you ignored the urge, or you’re psychologically suppressing your hunger, or other hormones are suppressing your hunger), it doesn’t mean you SHOULDN’T eat. Especially when you’ve eaten so little. Establishing a regular eating pattern will help regulate your hunger signals as well. It doesn’t mean you need to eat 5 meals a day. Just remember to feed yourself if you’ve gone a long time without food.

So is 500 calories a day healthy? No. Try your best to eat more. Because remember, “if thou eat less thou will burn even less!” — I’ve always liked that quote. 

I hope this helps :) I’m definitely getting into the habit of adding more calories to my meals (like extra butter or olive oil) because I’m only eating like twice a day now. So it helps without the bulk.