State bans on buying soda with food stamps are working, which is good for public health but bad for Coca-Cola, PepsiCo and the rest of big food.

• Soda purchases fell 13% in the 10 states that barred sugary drinks from food stamps this year.
• Even families with their own cash to spend cut back — the ban acted as a signal that soda is not real food.
• Food stamps send over $100 billion a year to 42 million families, so a large share of soda sales is at stake.
• Twenty-three states now have waivers, the first the USDA has ever granted, with more set to start this fall.
• Food and drink lobbyists are fighting the rules because losing food-stamp dollars hits their sales directly.

Outlook: More states are lining up to restrict soda and candy, so beverage makers should expect the sales hit to widen.