In response to some questions I asked Dr. Lerner regarding an article on the brain of bulimics http://www.eurekalert.org/pub_releases/2011-07/uocd-nbr071111.php , he wrote:
"I wouldn't overanalyze it but here's what the research suggests:
1. Both Cocaine, and related stimulant drugs [Adderall, speed, diet pills, etc.] flood the synapses with dopamine making us feel high and great, at least until the crash. Binge eating, loading on high glycemic foods [sugar, flour, fat] also flood the synapses with dopamine, albeit, it's a much more subtle effect for the food addict / bulimic.
2. This has been documented by PET scans and radiographic tomography showing the receptors lighting up like a Christmas Tree for both bulimics and stimulant addicts - Likewise, both substances [certain foods or volume of food and stimulants] will then cause not only the dopamine to rebound [creating a deficit of available dopamine]
3. It also DAMAGES the actual dopamine receptors in the brain. This damage to the structural part of the brain [dopamine receptors] is what we now know accounts for the protracted withdrawal and lingering craving that food addicts and cocaine addicts experience long after the substance(s) leave the system. It also accounts for the phenomenon of TOLERANCE. Less receptors = need for more and more dopamine to get high or even "normal" [sound familiar]
So...it can take some time for the receptors to regenerate [which they do]. Their destruction is a function of frequency and amount of substance [food or drug abused] and accounts in part for TOLERANCE [needing more of the substance(s) for the same effect]. Problem is, when you stop and they regenerate over time, tolerance dissipates and...wha la - you can OD if it's a drug and certainly get TRIGGERED big time if it's a binge food. Same happens with purging or compulsive exercising, or any addiction I suspect.
The relationship between food addiction - aka eating disorders - and stimulant abuse / dependency is what has been documented in the research for the past couple of years. WHAT'S NEW is the actual destruction of dopamine receptors. A similar process exists with a combination of difference receptors for other addictions [e.g. destruction of opiate receptors for opiate addicts, and so on].
As for ruminating thoughts [obsessive thinking], that may have to do with the above or be a product of both our personality type [someone OCD] and suffering with what most of us have, which I like to refer to as "monkey mind"...Monkey mind is our tendency to jump from one thought to another and another and another. Meditation is about noticing how our mind jumps around as if it were playing on monkey bars-hence "monkey mind"...we all suffer with it. Reining it in as we notice it jumping around is part of the work we do in recovery by "getting out of our own heads" as well as developing a spiritual connection to focus our attention away from the mind's playground.
Not sure if that answers your question. Feel free to see the article(s) and research regarding the above dopamine stuff at the "News" section of the Milestones website or FB pages. Hope it helps.