One of the things about having a messed up body from growing up overweight which happens is that you experience hunger differently. Your body tells you more often that you need to eat and you find it more uncomfortable to wait until your stomach is empty to eat. This has to do with psychology, of course, but it also has to do with biology. If you think hunger is only a matter of your brain's desire, then you need to learn about blood sugar ups and downs, insulin, and other aspects of endocrinology.
As I've been trying to lose weight (and succeeding, at least to some extent), I've been going through the uncomfortable process of fighting both my biological and psychological discomfort at not eating. My body isn't the same as a healthy, average weight or thin person's. Getting to the point of an empty stomach and then forcing myself to stay there is acutely uncomfortable. I get headaches and stomachaches. I feel very tense. My body is shouting for me to eat something because all of its systems are saying, "feed me!" It is used to being fed on a more regular and voluminous basis.
All of our bodies follow inertia. We have a point called "homeostasis" which is essentially a comfortable resting point. Bodies don't like to lose or gain weight. They don't like to be active when our normal state is to be at rest and they don't like to be at rest when we're usually active. The body likes its routines. Breaking the routines, from a physiological viewpoint, is very stressful for the body so it's going to fight you all the way.
If you don't believe me, consider the fact that it's common to catch a cold or get sick after losing a little weight. This happens because your body has been stressed by the changes you have forced upon it and your immune system is not as efficient. Your body has all sorts of changes to make and it's being overtaxed by them. It doesn't care that you may be healthier in the long run. It's just looking after its routines.
If you're fat, and you've been fat all of your life, you have a lot more inertia to overcome on the body changing front. Your body's systems have grown up being overfed and are very comfortable with that state. In fact, I don't know the biology, but I wouldn't be surprised if your bodily systems never fully adjusted to a state where you are comfortable being fed at an appropriate level. It's my hope that they will, but I'm pretty sure that my pancreas isn't open to logic and reason. It's just going to want to do what it has always done.
So, one of the things I've been doing as I struggle to lose weight is practice being hungry. It's very hard though because it's physically difficult and painful. I've been telling myself that the feeling that I'm starving and need to eat is an illusion my body is sending to me because it's afraid of change. I also am trying to form a connection between that feeling and a sense of accomplishment. That physical aching for food needs to be associated with success and accomplishment. If I endure it long enough and often enough, with any luck, I will train my body so that it reaches a new homeostatic point and it won't be so hard in the future to not eat.