I'm less than a month into Dx and I've read and learned a tremendous amount of information, I've changed my diet, and if I'm not fully OMS diet compliant it's not for lack of trying, but to inattention to detail, failing to check every ingredient on every item in the pantry!
I'm not sure how much the little bits and pieces of harm those ingredients will have on my body, but if it's a little or a lot, cutting it out can't harm me.
Though not a total westanivore, I didn't eat every meal with meat or cheese, but probably 8 or 9 out of 10, the biggest want has been cheese, so I've found that can be part of the struggle, (and I've survived the change so far). there are a couple of places tat we used to eat out at, meat on the menu, and an abundance of cheese, it's probably going to go on the "don't eat at" list, because there's not a single thing I can think of on the menu, that is vegan or vegetarian friendly, let alone dairy free.
There are a number of vegan, vegetarian and dairy free restaurants in the city, and I've already got a list of 5 or 6, well recommended ones, that I wouldn't mind taking folks to. I have determined not to fall off the oms diet wagon if at all possible, but mostly that means taking care to fill up when you can, carry some food in a "eiggod bag", (that's the reverse of a doggie bag, something that you take to the restaurant to eat if your plate is not full enough).
Good chefs should be willing to work with you, to make your visit to their restaurant, as good as it can be, if you go prepared, it shouldn't faze your experience, (but you have to be prepared), if you choose to go "on spec", you are risking breaking the OMS diet, and kicking your own ass.
The idea of a "special night of fun and debauchery", with all the forbidden foods on one plate, and then a week, a month or 6, trying to get back to an even keel, appears more than a little silly, and self destructive in the worst of ways.
Proper Preparation Prevents Piss Poor Performance, either research the menu or the restaurant that will work with the diet, or risk up to 6 months having to catch back up to where your control of the disease has you at today.
We are all grown ups here though, so if we choose to go off the diet, for a single meal, a single day / week / month, and things don't work out well, we have no one to blame but ourselves, but if we stick with the diet, and live as well as we can, for 10, 20 or 34 years there will time enough to pat ourselves on the back, for such good choices that we made over those years, later on down the road!