Mike, I hope you dont mind, but I did a bit of research for you in relation to this and your confusion of why you cant overcome it.
thought this info might be of interest(Im a concerned person by nature).....
"A great deal of research in recent years has indicated that there may be genetic factors that contribute to the onset of an Eating Disorder. This is not to say that emotional, behavioral and environmental reasons do not play significant roles, but that for some, there may be a genetic predisposition to the development of Anorexia, Bulimia or Compulsive Overeating.
Serotonin (ser-oh-TOH-nin) is a neurotransmitter, a group of chemical messengers, that carry out communication in the brain and body. The messengers travel from one neuron (or nerve cell) to others that act as receivers, where they attach to a specific area called a receptor site. This union, like a key fitting into a lock, triggers signals that either allow or prevent a message to be passed on to other cells. Since the discovery of serotonin in the 1950s, researches are finding evidence that one of its roles is to mediate emotions and judgement. (Serotonin and Judgement; Society for Neuroscience)
Serotonin is involved in many behaviors such as hunger, sleep, sexual response, impulse control, aggressive behavior and anger, depression, anxiety and perception. Abnormally low levels of serotonin might be found in someone who is suicidal, who is particularly agressive towards others, or a person who is extremely depressed. High levels of serotonin may be found in a person who is in a constant state of anxiety, has a tendency to be over-exacting in completely tasks, who suffers insomnia, or who has a tendency to feel overly stimulated by their surroundings (overwhelmed).
So how might this translate for someone with an Eating Disorder?
Low levels of serotonin, which could contribute to a person's sense of depression, are in theory, increased during episodes of binging, making the person actually feel better. As theorized, binging on sweets, starches or carbohydrates would increase serotonin and produce a sense of well-being.
In other words, those with low or high levels of serotonin may feel "driven" towards eating or not eating as they consciously or subconsciously realize it actually makes them feel better emotionally, because of a physical response in their brain.
It is very important to note that the act of restricting, and binging (with or without purging) can also lead to a disruption in serotonin levels, thus contributing to an already existing problem, or creating a completely new one to deal with. This can lead to depression and anxiety, which are known side effects of malnutrition and vitamin deficiencies, both for undereaters and overeaters.
What Do We Do With This Information?
Keeping the big picture in mind it may be useful to be aware of how serotonin levels effect each particular person when it comes to their course of treatment. Medications such as SSRIs (selective serotonin reuptake inhibitors) can help to control levels of serotonin and assist patients in responding more positively to therapy and treatment... but there is no "magic pill." Each individual will ultimately respond best when they can find a therapist and treatment team that can address all issues. "