When I first started counting calories, I had a horrible time because my body would nag and gnaw at me for more food. At that time, I wondered whether or not my body was permanently conditioned to desire more energy and if the struggle I was having with reducing calories was going to last a lifetime. In other words, I wondered if I'd always have to fight my body so hard or if my organs would adjust eventually and I'd slowly transmute my body into one which didn't rebel so hard against reduced food consumption. Frankly, I was pessimistic at the time.
Here's the thing; most people believe that "memory" is something that you only have in your brain. The truth is that every cell in your body has a memory. It isn't the memory of sights, sounds, smells, or feelings. It's the memory of how fluid, energy, damage, healing, etc. have occurred during the life of the cell. The cell is "used to" what it has had and it will fight to maintain normality. Just as a person may have difficulty adjusting to an income which is 1/3 what they were accustomed to as a reduction in lifestyle is harder than an increase, the cells in your body are going to cry foul when you chop out their accustomed feeding of energy.
Because our cells have their own memory, and they want more than anything not to change because change results in a disruption of your body's homeostasis, losing weight is hard. It's not only psychology or a lack of the much touted "willpower" that stops people from losing weight, it's each and every cell's desire to keep things as they were. During the initial phases of a food reduction plan, it is extremely hard to fight the impulses your body is sending and your brain is translating into giving you strong urges to eat. You're being compelled by potent biological forces.
The nice thing about cellular memory is that it will eventually "forget" its old state of normalcy and adapt to a new one. After you clamber over the initial mountain of difficulty of eating less, it gets easier. I've found that, despite my fear that my body was built to overeat, it does seem to have adapted and the road, while never exactly easy, has gotten far less rough. If you can do it for a month (without retraining your body to a higher intake of energy by cheating or slipping), you can do it for a year. It's that first month that's the hardest part.