Fast food does exist in Paris; they love their ‘McDo’ but hate to admit it. And you’ll see people taking their lunch break in the Tuileries or Luxembourg Gardens eating emporter (to go) sandwiches. The French version of fast food is a far cry from McDonald’s–it’s actually very good. If you are on the run, what with all the things one must do here in a short period of time, I suggest you head to any one of Eric Kayser boulangeries sprinkled about the city for yumminess that gets you in and out in a hurry.
I do believe you’d be safe bringing them here for lunch as well. They serve delicious sandwiches and savory tarts that people will stand in line outside the door for. If tables are hard to come by at lunch time, why don’t you treat yourself to dining al fresco with your family or whoever you’re traveling with. Get your meal to go (emporter) and create an impromptu picnic in the Tuileries. Speaking from experience, lunch in the gardens is pretty darn magnificent.