Overeaters Anonymous (OA) is a twelve-step program offering a program of recovery from compulsive overeating and other eating disorders using the twelve steps and twelve traditions as interpreted by OA. Participants need not be overweight — in fact, some OA members are bulimic or anorexic. Like other twelve-step groups, OA groups typically meet weekly. More women than men participate in this program in most locations; but all OA groups welcome anyone who has a desire to stop eating compulsively.
Like members of Alcoholics Anonymous, members of OA generally hold that they have an illness of the body — an abnormal reaction to certain foods and/or eating behaviors which creates uncontrollable cravings, similar to the alcoholic's cravings — and an illness of the mind — an obsession of the mind which continues to find reasons for returning to those foods and eating behaviors (reasons ranging from severe emotional upsets to rationalizations like "I've been good in the last hour/week/year"). But also like AA, OA is clear that the solution offered is a spiritual one — the practice of the Twelve Steps.
OA members do not all have a specific or a common substance or attribute which causes binge or compulsive eating. Experience in OA has shown that different members develop cravings from different kinds of foods or eating behaviors, and therefore each member has to develop her or his own plan of eating. Since people must eat to live, OA uses the concept of "abstinence from compulsive eating" rather than "sobriety"; a plan of eating would ideally, therefore, eliminate those foods and/or eating behaviors which cause cravings.
However, it is a common misconception in OA that each OA member must (or may) come up with her or his own definition of abstinence. According to OA Conference Approved Literature, specifically a number of OA pamphlets, "in Overeaters Anonymous, abstinence is the act of refraining from complusive eating." Some members have suggested that this definition is less than helpful, leaving open, as it does, the definition of "compulsive eating." But the OA Conference Approved pamphlet entitled "Questions and Answers about Compulsive Overeating" states that "a dictionary definition of compulsion is a feeling of being irresistibly driven to the performance of an irrational act." So a simple synthesis of these two definitions can clearly provide the Overeaters Anonymous definition of "abstinence" as follows: "In Overeaters Anonymous, abstinence means the act of refraining from irrational eating which is driven by a feeling which seems irresistible." Otherwise, OA functions just like any other twelve-step program.
OA was founded on January 19, 1960, in Los Angeles, by two individuals, one of whom, Rozanne S., has remained in the program (despite personal struggles with abstinence) since its inception and is considered the co-founder of OA. Its headquarters are currently in Albuquerque, New Mexico. There are approximately 6500 meetings in 60 countries, and its estimated membership is around 70,000.
There is extensive OA literature available. OA members also use AA literature.
While many OA members have experienced dramatic weight losses, sometimes of hundreds of pounds, publicity as to the effectiveness of this program may be hampered by OA's tradition of anonymity. OA has adopted and adapted AA's Twelve Traditions; accordingly members do not identify themselves as OA members at the level of the press using their real names or faces.
An important point of the OA program is spiritual faith. The program is non-denominational and not specific to any deity, but faith in a Higher Power is central to the program.
Overeaters Anonymous does not endorse any particular plan of eating. Some members of OA use the following elements in their recovery.
Eliminating addictive substances from the diet completely. This varies from person to person, and Some people eliminate alcohol, caffeine, sugar, white flour, all flour, and wheat, along with other items that are personal addictions, or triggers for binging.
Not eating between meals AT ALL (3-0-1 Plan of Eating: 3 Meals a day, 0 snacks, One Day at a Time)
Developing, with support, a food plan that is well planned and balanced, weighed and measured, and sticking to it absolutely - Not one bite more, not one bite less.
Eating your planned meals at regular times each day
A. Writing down a food plan each day, for the following day, so that no time is needed to think about what is to be eaten today. B. This planning is best done after all that day's food has been consumed. C. Once written, not changed.

More info, help links & Source:
http://en.wikipedia.org/wiki/Overeaters_Anonymous