Taxes have been an effective approach to curbing the consumption of tobacco, alcohol, and soda in America. Why wouldn’t a tax on junk food work as well? A junk food tax—on “non-essential” foods like candy and potato chips—has been shown to work in Hungary and Mexico. In fact, people in Mexico are buying 7 percent less junk food than they would have if the tax hadn’t been imposed. It’s time the US considers such a tax if it wants to fight obesity.