My experience, in my opinion.
Heres what I know about OA history. Way before 1970 when I first went to meeting, OA had a food plan called the grey sheet. It was very restrictive and didn't meet everyones health needs. As time went by, suggeted foods plans were introduced in a pamplet. Abstinence was defind as "refraining from compulsive eating" and no plan endorsed. Later on a new faction in OA emerged calling their meetings OA HOW, and returned to a the grey sheet as a means to abstinence. If you were not doing the grey sheet, you were not abstinence unless a doctor told you not to use that plan. I personally, found it humiliating to be told I was a failure if I didn't choose that plan. And, at that time, you weren't allowed to speak at meetings if you weren't abstinant.
I am not familiar with the OA 90.
Anyway, I finally designed a plan that was healthy and worked for me and I lose weight. I personally find that 5 smaller meals makes me feel less crazy than 3 larger meals a day. I don't feel crazy most of the time.
My advice, get a healthy plan from your doctor.
About me: I am 62 years young. I started my weight loss journey in January 2011 at my top weight of 350. I made a decision at that time not to diet, but to make a lifestyle change.
And today, I am renewing the journey.