Soda Taxes Show Little Impact At Fast Food Drive-Throughs

Soda Taxes Work at Supermarkets, Research Suggests Fast Food Is a Different Story

Sugary drink taxes have become one of public health’s favorite tools for fighting obesity. Cities from Philadelphia to Seattle have passed them, betting that nudging up the price of a Coke or Mountain Dew will steer people toward healthier choices. At the grocery store, that logic has some teeth. At the fast food drive-through, according to a sweeping new study, it appears to have little effect.

Researchers at New York University analyzed six years of sales data from 120 Taco Bell locations, selected from a nationwide dataset of thousands of restaurants, across five U.S. cities and counties that enacted sugary drink taxes between 2015 and 2020. Despite the taxes, customers did not meaningfully reduce the calories they bought from beverages. Prior research has linked soda taxes in grocery stores to roughly a 15% drop in sugary drink sales, but fast food restaurants appear to be a different animal.

About one-third of Americans eat fast food on any given day, sugary drinks make up more than 80% of beverages listed on fast food menus, and roughly 16% of all sugary drinks consumed in the United States are purchased at fast food counters and drive-throughs. A tax that doesn’t change behavior in the drive-through lane leaves a sizable chunk of sugary drink consumption untouched by one of public health policy’s most talked-about interventions.

Six Years of Drive-Through Data, One Surprising Answer

Led by Pasquale E. Rummo and Brian Elbel at NYU’s Grossman School of Medicine, the research team drew on transaction-level data from 7,341 Taco Bell locations nationwide, representing nearly 6.86 billion purchases from 2015 to 2020. Taco Bell, the third most popular fast food chain in America, is a place where half the U.S. population eats at least once a month. From that nationwide dataset, researchers zeroed in on 60 restaurants in five jurisdictions with sugary drink taxes: Albany, California; Cook County, Illinois; Oakland, California; Philadelphia, Pennsylvania; and Seattle, Washington. Tax rates ranged from one to just under two cents per ounce.

To build a fair comparison, the team used statistical matching to identify 60 similar restaurants in areas where no soda tax ever existed, essentially constructing a “twin” for each taxed location. Researchers then tracked how beverage calories per transaction changed over time in both groups, separately for individually purchased drinks and combo meal beverages.

Because only drive-through orders allowed more consistent calorie estimates (employees pour those drinks, so the size is known), the analysis covered drive-through purchases exclusively. Those accounted for about 70% of all transactions. Self-serve fountain drinks ordered inside couldn’t be reliably measured. Findings were published in PLOS Medicine.

What the Soda Tax Numbers Showed

Across all five locations, the taxes produced no meaningful change in beverage calories. During the three-to-24-month follow-up period after taxes took effect, individually purchased drinks showed a difference of just minus 0.3 calories between taxed and untaxed restaurants, a number statistically indistinguishable from zero. Combo meal beverages showed a difference of minus 4.3 calories, also not statistically significant.

Breaking results down by city told a mostly similar story. In Philadelphia, Cook County, Seattle, and Albany, the taxes showed no meaningful impact on beverage calories. Oakland was the one apparent exception: customers there bought an average of 16.8 fewer beverage calories per combo meal transaction compared to the control group, roughly a 14% reduction. When researchers dug deeper, though, that effect vanished once they accounted for whether customers had actually ordered a drink with their meal, suggesting some customers skipped the drink altogether rather than choosing a lower-calorie option.

Both Oakland and Philadelphia did show reductions in total calories per transaction (45.7 fewer in Oakland, 28.2 fewer in Philadelphia), even though beverage calories didn’t budge. Researchers suggest customers in those cities may have shifted which food items they ordered after taxes went into effect, rather than changing their drink choices.

Why Soda Taxes May Struggle at the Drive-Through

Part of the explanation comes down to behavior. At a grocery store, a shopper facing higher soda prices can leave it on the shelf, drive to a neighboring town, or swap it for water. None of those options make much practical sense at a drive-through window. A customer pulling in for a quick lunch isn’t going to cross a city line to save a quarter on a soft drink. When a drink is bundled into a combo meal at a single price, the tax may barely register.

A companion analysis by the same team, using the same data, found that how much restaurants actually raised prices varied sharply by location. In Philadelphia and Cook County, where taxes covered both sugary and diet beverages, restaurants passed the full tax on to customers for individual drinks. In Oakland, Seattle, and Albany, prices didn’t move at all. Even in cities where the price went up, customers kept ordering the same drinks.

At one to two cents per ounce, a 20-ounce soda costs roughly 20 to 35 cents more. On an $8 or $9 meal, that’s easy to overlook.

Researchers also raised the idea of a “signaling effect,” where public conversation around a new tax nudges people toward healthier choices regardless of price changes. That could help explain why total calories dropped in Oakland and Philadelphia even when beverage calories held steady, a kind of indirect awareness effect rather than a straightforward price response.

One wrinkle in the data: 47 of the 60 taxed restaurants, nearly 80%, were located in Cook County, Illinois, where the tax was repealed after just four months. Researchers ran multiple checks to account for Cook County’s outsized presence in the sample, and the overall conclusions held.

A Reality Check for Soda Tax Supporters

None of this makes soda taxes useless. Evidence remains solid that they cut purchases in grocery stores and pharmacies. And the total-calorie reductions seen in Oakland and Philadelphia hint that taxes may produce broader, less obvious shifts in eating behavior worth exploring further. But for the roughly one in six sugary drinks Americans buy at fast food restaurants, the current penny-per-ounce approach doesn’t appear to be moving the needle in fast food drive-through settings.

As the study’s authors concluded, the sizes of sugary drink taxes currently in place in the United States appear to be “too small to change beverage calories purchased in fast food restaurants.” Whether larger taxes, different structures, or redesigned beverage menus could succeed where current policy has not remains an open question.

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