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Governments around the world are grappling with how to tackle obesity epidemic. Central to this are attempts to reduce consumption of junk food -- foods high in calories, salt, sugar, fat, fiber, protein and vitamins. Junk food markets, such as those for confectionery, soda, and potato chips, share a number of common features; They tend to be dominated by a small number of firms that sell multiple brands and heavily advertise their products. A number of organizations have called for restrictions on advertising of junk food as a means to reduce consumption.

The effects of such an intervention are complex and will depend on whether advertising predominantly acts to expand the market size, or steal rival market share, what products consumers who substitute out of the market switch to instead and how the firms in the market adapt their behavior in response to a ban.