Weekends used to be tough for me, too, but with time--and effort-- I figured out strategies that work for me. Make a list of the foods that you will regret eating-- this is usually very predictable. Then a basic list of those you can enjoy without a problem. I know what drinks I can have, what appetizers, main dishes, etc, at most of the popular places in my area. Nowadays most have webpages with their menus so you can figure out 5-6 options, which takes the worry away, and gives no excuse for cheating. If you go to peoples house, make/take some primal goodies (mine usually get eaten pretty snappy). Or my last resort is to say I'm having health issues and can't eat x-y-z, and most people will respect your needs.
This time, like all times, is a very good one, if we but know what to do with it. Ralph Waldo Emerson
Any given day you are surrounded by 10,000 idiots. Lao Tsu, founder of Taoism