Episode 101: Sugar taxes

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It’s been a while. Thank you for sticking with us while we’ve been gone.

Dozens of countries have started taxing sugary drinks over the last couple of decades. You can see the reasoning: if they cost companies more to make, then companies will pass that cost on to consumers, who will buy less, and hopefully get less fat and then die less often of diabetes and heart disease.

But does that actually work? We had a look at the studies behind it.

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• Germany’s planned tiered sugar levy — the announcement (and a bit more detail on the €0.26/€0.32-per-litre thresholds)

• The WHO’s Global report on the use of sugar-sweetened beverage taxes, 2025

  • The World Bank’s Global SSB Tax Database, the source for the “100+ jurisdictions” figure

• Chris Snowdon / IEA’s case against sugar taxes: the classic Sugar Taxes: A Briefing and, more recently, The bitter truth about the sugar tax in The Critic

• Andreyeva et al.’s 2022 meta-analysis in JAMA Network Open.

• Scarborough et al.’s 2020 PLOS Medicine paper on UK reformulation.

  • The UK Government’s November 2025 Strengthening the Soft Drinks Industry Levy consultation

• The substitution question:

  • 2021 Seattle study (difference-in-difference vs Portland; drinks sugar down, sweets up a bit)

  • 2025 Chinese modelling paper (the +2.57% total-calorie result in low-income families)

  • The IZA discussion paper on the UK levy (no substitution to other sweet drinks)

• The modelling studies:

  • 2017 Mexico paper (86–134k diabetes cases “prevented” by 2030)

  • Scarborough et al.’s 2024 PLOS Medicine PRIMEtime model

  • Sánchez-Romero et al.’s 2016 PLOS Medicine Markov cohort simulation

• The direct, empirical outcome studies:

  • The 2024 Philadelphia BMI study (the one that found only six prior studies; null panel sample)

  • The 2025 California study (small effects, wide error bars)

  • The Mauritius study (no significant BMI association)

• The big one — Rogers et al.’s 2023 PLOS Medicine interrupted time series on English schoolchildren (the 8% relative reduction in year 6 girls; 5,234 cases “prevented”)

  • Chris Snowdon’s demolition of it, including the 2013–2018 counterfactual buried in the supplementary material

• Gallup on the recent US obesity decline coinciding with GLP-1 drugs

The Science Fictions podcast is produced by Julian Mayers at Yada Yada Productions.