Why Is Junkfood So Good??

So I wanted to go to the cub to buy some flaming hot Cheetos cause I ran out so me and Olivia walked to the cub. when we got there I found the Cheetos and grabbed a bag. As we were walking around we saw this bag of GIANT marshmallows it was so weird we both looked at each other and got this insane idea to see how many we could fit into our mouth. We walked down the isle and also grabbed a tub of double bubble and a 2.5 pound bag of gummi worms. When we got home we set all of the stuff down sat down and tried to stuff as many marshmallows as we could into our mouths. Sadly the most we could fit was 2 but we both ate 25 pieces of gum each. My stomach is still a little queezy around junk food but the one question that kept running through my mind was "why in the world does junk food taste so darn good!?"