If you must eat fast food, don't buy an entire meal. Just buy the sandwich or whatever it is you want. It's more than enough calories...I mean, you can check on their websites ahead of time if you're not sure, but come on, we all know they are.
So skip the fries and soda, get a cup of water instead. And steal fries from your husband's meal (who cannot possibly be convinced to give them up...but then again, I don't try THAT hard) like I do. Think of it this way, you're helping HIM to stay slim too, even without giving them up altogether!