People don't have infinite willpower. There is no magical distinction between minds and bodies. We are just animals and we are
genetically programmed to strongly desire to eat food. The
vast majority of people who attempt to diet fail.
When diets work, they require pushing the body to the point of starvation and keeping it there, which is just not sustainable. The body goes into starvation mode and tells the brain to do everything it can to sustain food. No amount of willpower can overcome that.
http://www.nytimes.com/2007/05/08/health/08fat.html?pagewant...
> fat people who lost large amounts of weight might look like someone who was never fat, but they were very different. In fact, by every metabolic measurement, they seemed like people who were starving.
>The Rockefeller subjects also had a psychiatric syndrome, called semi-starvation neurosis, which had been noticed before in people of normal weight who had been starved. They dreamed of food, they fantasized about food or about breaking their diet. They were anxious and depressed; some had thoughts of suicide. They secreted food in their rooms. And they binged.
>Eventually, more than 50 people lived at the hospital and lost weight, and every one had physical and psychological signs of starvation. There were a very few who did not get fat again, but they made staying thin their life’s work, becoming Weight Watchers lecturers, for example, and, always, counting calories and maintaining themselves in a permanent state of starvation.