As it is a holiday weekend, I know we are all thinking about BBQs and pool parties. My advice? ENJOY it! Eat what you want, just don't go overboard. Anticipate that you are going to eat unhealthy and maybe squeeze in a workout beforehand. Rather than going into it thinking, "I can't have..." go into in thinking, "I can have..." Give yourself the freedom to indulge. It's a holiday! As long as you don't eat like this all the time, you won't have to worry about becoming unhealthy or gaining weight.
I do not agree with diets that tell you to bring your own food to the holiday dinner. Unless your doctor tells you it's a health risk to eat something, what is the harm of indulging on the holidays? If you deprive yourself all the time, without an occasional treat, you may develop an unhealthy relationship with food.
So enjoy this weekend, eat some BBQ and don't feel guilty! Then on Tuesday, stay away from the scale--because it probably won't be the number you want it to be--and get back on track with your diet and exercise.