I have to straddle the fence on this issue. I know that you should eat only when you are physically hungry but a lot of people who overate (especially for years) have ruined that sensitivity to be able to gauge. Not to mention that some of us overate so much we stretch our stomachs out so it feels like we are more hungry for a reason----our stomachs can hold a lot more food. Again, this is the basic principle behind stomach reduction surgery. The doctors have known this for years. Or has been said, "Nature abhors a vacuum". It just aches to want to fill it.
So, what I do is a combination of both. I keep one eye on weighing and measuring my foods while also gauging my fullness level. If you aren't, I really recommend that you do even for a couple of meals. I think, a lot of people really think they are eating little when in reality they are eating a lot ----a lot of calories that is. When I mean weighing and measuring, I mean everything-----from the condiments on the sandwich to the salad dressing to the size of that chicken breast. Depending on how you "doctor up" a chicken breast it can become very calorie-dense if you aren't careful.
As for being concerned about the future, if you train your body meal by meal you will arrive at your desired goal:" to be able to know when to stop". However, this is a caveat: sometimes, we know when to stop, we just don't. I do not want to stop eating pizza when I am full. Sorry, but I don't. Neither do I with my homemade fudge. I want to eat and eat and eat. That is how you get and stay fat. Eating the foods that you can't or won't stop overeating. Quite honestly, if you gave me unlimited pizza from my favorite pizza place vs unlimited sex, I would say bring on the sausage!!
The choice is simple.
Eat to be thin or eat to be fat. Calories are just one marker of what your choice will be. Undereating is not virtuous in of itself. You aren't going to get a gold star because you underate one day. In fact, over the long run you could actually bring on some serious nutritional issues with your body.
Eat to live not live to eat. says Geneen Roth.
Your body needs good healthy food. The reason why I eat more than you is because I have found that in order for me to get all the necessary servings of grains, lean protein, fruits and especially vegetables, I need to eat more than 1300 calories. I never realized that I was undereating protein especially for my weight and body size. My hair was lacklustre and so terribly thin. My metabolism was slower than a centipede on a 5K run. My skin was gray and sallow.
When I stepped up my protein so did my metabolism. My body need for 10 grams of protein is almost 1000 calories right there and you know that I want a little something to go with that. Just by making that one change this past winter I have noticed some great results. The benefits??? Weight lose for one but more importantly. My skin glows. My hair is coming in thicker. My menopause symptoms like hot flashes are almost non-existent. I say my body is getting the amount of food it needs. I hope you will do the same. Your body will thank you in the long run.