City-Level Sugar-Sweetened Beverage Taxes and Changes in Adult Body Mass Index
Authors' conclusion
In this cohort study, SSB excise taxes were associated with reduced mean BMI among adults in demographic subgroups, including in young adults who consumed the most SSBs, and in Berkeley. Future research should examine the mechanisms of these associations to inform how SSB taxes could be more equitable for weight-related outcomes.
Study context
- Population
- Kaiser Permanente members aged 20 to 65 years with ≥1 pretax and ≥1 posttax body mass index (BMI) measurement, California cities, January 2009 through December 2020
- Participants
- 178,931 vs 865,343
- Exposure
- Cities with sugar-sweetened beverage (SSB) excise taxes vs matched cities without SSB excise taxes
- SSB tax citiesn = 178,931
- Control citiesn = 865,343reference
- Outcome
- Mean BMI and proportion of adults with overweight or obesity (differences-in-differences (DID))
- Follow-up
- 6 years before to 4 to 6 years after the tax
Methodological detailsdifference-in-differences analysis, demographically matched control cities, electronic health record data
- Difference-in-differences analysis
- Demographically matched control cities
- Electronic health record data
Main finding
As reported in the abstract
Mean BMI and proportion with overweight or obesity, overall
- No overall differences in BMI or proportion with overweight or obesity
Observational data: associations, not effects.
Further findings
| Outcome | Estimate |
|---|---|
| Mean BMI by subgroup (DID estimates)SSB tax cities vs Control cities | DID estimate, age 20-25 years −0.30 (95% CI −0.51 to −0.08) |
| Mean BMI by subgroup (DID estimates)Between SSB tax cities and Control cities | DID estimate, age 26-39 years −0.19 (95% CI −0.37 to −0.20) |
| Mean BMI by subgroup (DID estimates)SSB tax cities vs Control cities | DID estimate, female −0.19 (95% CI −0.26 to −0.11) |
| Mean BMI by subgroup (DID estimates)SSB tax cities vs Control cities | DID estimate, White −0.19 (95% CI −0.35 to −0.04) |
| Mean BMI, BerkeleyBerkeley vs Control cities · statistically significant reduction | DID estimate −0.16 (95% CI −0.27 to −0.04) |
Parts of this Brief are withheld: the automatic checks could not confirm them against the abstract.
Original publication
City-Level Sugar-Sweetened Beverage Taxes and Changes in Adult Body Mass Index. JAMA Netw Open. Published 2 January 2025. doi:10.
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