Deerhound welcome. I hope one of the more experienced posters will explain this more.
There is a 55p leaflet on Abstinence at Abstinence
My understanding is that you commit to avoiding overeating, and some people do commit to avoiding certain trigger foods.
According to dear Auntie Wickepdia...
"Abstinence in OA
“Abstinence in Overeaters Anonymous is the action of refraining from compulsive eating and compulsive food behaviors while working towards or maintaining a healthy body weight.” [10] This concept of abstinence has been criticized for its lack of specificity. While in AA abstinence means not drinking alcohol, some argue that it is not possible to set out specific foods, because OA's experience is that different people have different food triggers (i.e. foods and food behaviors that cause them to eat compulsively). While it is often said that alcoholics don't have to drink, but compulsive eaters still have to eat, Overeaters Anonymous responds by pointing out that alcoholics do have to drink, but cannot drink alcohol, just as compulsive eaters do have to eat, but cannot eat foods which cause compulsive eating.[11]
OA literature specifically defines "compulsion" as follows: "By definition, 'compulsion' means 'an impulse or feeling of being irresistibly driven toward the performance of some irrational action.'"[12] Therefore, "compulsive eating" and "compulsive food behaviors" (as those terms are used in OA's definition of abstinence) means irrational eating, or irrational food behaviors, taken as a result of an impulse or feeling that feels irresistible. So, according to Overeaters Anonymous, "abstinence" is the act of refraining from "compulsive eating" and "compulsive food behaviors," while working towards or maintaining a healthy body weight. While this definition can fairly be described as nuanced and subject to personal interpretation (e.g., the definition of a "healthy body weight"), or requiring self-searching analysis (e.g., to determine the drivers of certain behaviors), it is not unspecific.
The objective of OA's definition of abstinence is that the compulsive eater refrain not from eating, but rather, from compulsive eating and compulsive food behaviors, and work towards or maintain a healthy body weight. Thus, OA calls for the compulsive eater to define his or her own plan of eating which enables the compulsive eater to abstain from compulsive eating and compulsive food behaviors, while working towards or maintaining a healthy body weight.
The program suggests that members identify the foods that "trigger" overeating. Since individuals are responsible to define their own plan of eating, they are able to change their plan of eating if their needs and understanding of their compulsions change, without that change constituting a breach of abstinence. Members are encouraged to seek counsel with other individuals, generally including a member or members of the OA fellowship, and, most importantly, with their "higher power," before making such changes, to validate that the reasons are sound and not unwittingly a decision based on underlying compulsion.[11]"
wikipedia