Totally avoid the chips and the Margarita's at all costs! Tons of empty delicious calories there!
At our nearest Mexican restaurant they have a grilled chicken and pepper dish. I skip the tortilla shells and sour cream and load it with the lettuce and tomato, avocado and salsa. It's really good and I estimate it to be around 500 calories...give or take on how big the chicken piece is. The scale is usually kind afterwards.
Don't be afraid to ask a lot
of questions and special order
your food....If you embarrass your family enough with all your questions/demands of the restaurant, then maybe they won't force you to go to such "UNdiet-friendly places anymore.
(This has worked for me!)