I could have sworn I heard something once about how fast food chains put addictive chemicals in their food. For me, I don't have an addictive personality. There's nothing in my life I feel addicted to other than fast food. It's weird. I know the food is dogshit and I can make tastier stuff at home. But I also think about getting fast food all the time and have to stop myself from ordering it a lot. It does kind feel like a dopamine hit when I open up a bag of fast food and start digging in.
Yes, it's called sugar(carbs), fat and salt. Pick one or two of those, and your brain will eventually get overwhelmed and you'll feel like washing your mouth out.
Pick all three, and the food never stops tasting good, and you'll eat until you physically have no room left.