Boy oh boy, you women are just awesome! I love the ideas presented here and the way you have all stepped in to offer your ingenious coping strategies to each other. This kind of sharing is SO important.
I fully agree with Tia that just stating matter of factly, something along the lines of, "I have digestion problems and they result in multiple food intolerances.", is the most detail you need to get into. If you take firm responsibility for what you can and can't eat and do not act apologetically or embarassed, they will more quickly develop respect and acceptance around your decisions about what is right for your health. If they press you can clearly state that you will feel ill if you eat foods other than the ones you tolerate well and leave it at that. If necessary, again, you can affirm that you choose only to eat foods that make you feel good. Getting into the details with anyone other than close friends just exposes you to uninformed judgements from the folks who don't understand.
Then all you have to do is resist the temptation to eat foods that will make you feel ill! Lao Tzu, a famous Taoist teacher says, "I can resist anything except temptation."
Take good care guys and keep up the great work!