Struggling!

So I have been eating low carb/low sugar for two weeks this Thursday, and tonight I LOST it!! I went crazy like a kid in a candy store and ate TWO!!! cheeseburgers from McDonald's plus a medium fry. I have been tracking my calories on the MyFitness Pal App (which I love!!), and according to it I ate 980 calories just for dinner! It's kind of disgusting really! Why do we do this!? I don't know if I am the only one, but surely there are others? We do so good for such a long time and then all of a sudden we lose it. It's so hard! I have to keep my focus! I need to get healthy. I need to live longer. I need to be around for my Princess.