Why is food that is bad for you so addictive/good? I need some advice.

Sugar. because it has sugar, salt and fat. which makes the pleasure centers of the brain really happy. http://www.amazon.com/End-Overeating-control-insatiable-appetite-ebook/dp/B0025VKJNA/ref=sr_1_7?ie=UTF8&qid=1408074077&sr=8-7&keywords=sugar+salt+fat.