If you must have your sour cream and guacamole, order it on the side. Avoid fried foods. These foods include tacos, chimichangas, etc. You can substitute for soft tacos, and baked quesadillas. Avoid food with ground beef in it.
Mexican food tends to have big portions.
You might like to cut the portions in half and put in a to go box. Mexican desserts tend to be fried and topped with honey. Avoid these desserts. Try to find an alternative, instead of fried desserts get fruits. You don't have to sacrifice to enjoy Mexican food.