I am not a fan of fast food, but if I have to choose then french sandwich is the best meal for me!
I have read a lots of studies about the fast food and listening some sport professionals what they think about that food and I realize one thing. If you never have a physical activity during your day, then every food will be unhealthy for your system.
I mean, I don't want to say that fast food is a healthy choice if you training something, no! But, you will never have good results if you don't training something. Even if you eat a hamburger ones in the week, you will not have any problems with the fast food.
Keep in mind, that fast food is also a GMO product!