The meat in burgers is fried, and it is inevitable that it contains carcinogens when it is fried repeatedly in one pot of oil.

While those fast-food restaurants may claim that they use good oil and change it often, in reality the new oil has already produced toxic substances after frying something once and should be discarded. But obviously, fast-food restaurants can't fry a piece of meat and change the oil in a pot.

Also burgers are loaded with tons of salad dressing, something that's high in cholesterol and calories and not advisable to eat much of.