Its not food, just fat, salt, preservatives & sugar that will make you fat & kill you.
A lot of them are high in calories and low in beneficial nutritional value but they're cheap and fast so people buy more and more
Fats, fats, fats, and grease. Lots of refined sugars. Practically no nutritive value. You want more?
Excessive amounts of fat and salt, and usually more calories than a person needs - unless they have a very small portion. Fast foods are also addictive, making people want more and more of them and less healthy food.
chemicals + processed food
Too much is bad.