Ostensibly, there is only one way to achieve food sobriety - stop eating compulsively - and the end goal of this sort of sobriety is to work toward a healthy body and weight using the same spiritual tools used in all twelve step programs. When in OA, you create a meal plan and you stick to it and that constancy is a step to recovery. Your meal plan is what you make it - there is no one "OA-approved" method of eating, which means you can have vegans, low carb, high carb, intermittent fasters and every variety of eating style in one meeting and the focus should be on how they dealt with their meal plan, not what you think of the validity of their food choice.
What do you think happens when people face a Chantal in meetings, rolling her eyes at your snack of turkey pepperoni on whole wheat crackers because some quack site says pepperoni is a major carcinogen? Or when you discuss a major victory at a family gathering wherein you ate a tossed salad and grilled chicken and avoided the cake and potato salad you knew would trigger a desire to binge and you have potato head over there snorting about how she just doesn't understand how anyone could consider it a victory to eat a poor defenseless animal.
OA demands that you engage in a spiritual recovery and in spiritual matters you turn inward and face what you know is weak about your character. Many compulsive and binge eaters are already full of self-loathing and hyper-self-criticism fuels destructive eating behaviors in a lot of super-obese people. So you get this person who hates herself, who is taking positive steps, working the program, trying hard to find why she eats so much, and she faces a cabal of Chantals who snidely and cruelly demean her success because she didn't eat organic, because bloodmouths are Satan, because she should eat locally, because she should have cooked the meal herself, because eating differently from those around her made her probably made her family nervous and on and on and on. The focus stops being on helpful self-contemplation and becomes devoted to a cult-like examination of every single morsel the person ate and why it was wrong of them to have eaten it. You will see behemoths like Chantal rigorously looking for any weak spot to expose in someone else's recovery because it gives them the easy thrill of subjective moral correctness while avoiding actual personal improvement.
Even more appalling is the number of Fit Vegan Ginger types who began as maybe 20 pounds overweight, if they were overweight at all, but started attending OA meetings because they were obsessed about their wickedness where food consumption was concerned and needed OA to bolster their restrictive and disordered eating while pretending they were trying to get better. They can manage to turn OA meetings into an anorexic Jim Jones in North Korea shit fest of confessing sins or wrong think regarding all food choices. You misjudged what you needed to eat one day and ate a banana not planned for? You have a character defect and must analyze all your many failings that make you so weak and if you continue this behavior of out of control eating then others may need to avoid you in order to save themselves from your moral chaos. Chantal might not have the charisma to launch such a clique but she'd take to the nastiness and mentally ill woo-think like a duck to water.
In groups that go south, moderators fight to keep meetings on track but people who want to do the work never get the chance or they are made to feel so bad about themselves they drop out and continue the self-destructive cycles.
