Put something in fast food?

Do you think they add something to fast food to make it addicting? I went a year without fast food, never thought about it never craved it. But one day I was super hung over, and my friends stopped and got me a mcdouble and fries. 4 months later im still eating it and I'm eating it all the time. I literally crave it! I never experience this with any other food but fast food. 
This is still happening. Il go a week or 2 without it, but that one time I stop, I just stay craving it every day. And it's hard to overcome it again! I feel it's weird this only happens with fast food. Do you think they add something to make it addictive? Any one else can relate?  
😩😩 umm rude, I have self control lol but that doesn't mean I don't crave the food about a week after eating it. I didn't ask why I keep eating it... I asked why do I get that addictive craving feeling