Department of Research & Evaluation News

After 4 California cities began taxing sugar-sweetened beverages, young people in those cities had lower body mass index (BMI) compared to young people living in cities without the tax, a new study shows.

“The findings of our study demonstrate that SSB (sugar-sweetened beverage) excise taxes may be associated with lower BMI percentile among youth,” said the study’s lead author Deborah Young, PhD, MBA, director of the Division of Behavioral Research at the Kaiser Permanente Southern California Department of Research & Evaluation. “While these findings show us there is a way to have a positive impact on children’s health, additional research is needed to determine if the tax resulted in reduced purchases and consumption by youth or the additional programs from the increased revenue was responsible for the results we found.”

The study was published in JAMA Network Open. It was conducted between 2009 and 2020 and included over 390,000 Kaiser Permanente members between the ages of 2 and 19 years old. The researchers compared 4 cities with sugar-sweetened beverage SSB excise taxes — the California Bay Area cities of Albany, Berkeley, Oakland, and San Francisco — to 40 California cities without SSB excise taxes.

Findings of the study showed benefit varied by age

Findings show:

• Youth below the age of 12 had significantly lower BMI percentile, lower proportion of overweight/obesity, and lower proportion with obesity compared with similarly aged youth living in control cities.
• These results suggest that effects of the taxes on youth weight status may be greater among younger children.
• Males in cities with the taxes had a lower BMI percentile compared with males in control cities.
• Asian and white youth in cities with SSB taxes saw a significantly lower BMI percentile compared with control cities.

Prevalence of obesity among youth is high

About 16% of U.S. youth were overweight and 19.3% were obese in 2017 and 2018. This excess weight increases their risk of current and future chronic diseases. Although there are many contributors to the prevalence of obesity, researchers say it is clear that sugar-sweetened beverage consumption has been associated with obesity in numerous studies.

In 2019 the American Academy of Pediatrics recommended fiscal policies like SSB excise taxes to reduce obesity. Berkeley was the first U.S. city to levy an SSB excise tax in 2015. The 4 Bay Area cities in this study levied a $0.01/ounce excise tax onto sugar-sweetened beverage distributors. The excise taxes were passed onto consumers. Sugar-sweetened beverage purchases and consumption declined in these cities and revenues from the tax largely funded public health and equity programs.

Annual revenues ranged from $273,000 in Albany to $16,098,000 in San Francisco, with most of the revenues supporting health-related programs (100% in Albany, 92% in Berkeley, 79% in San Francisco, and 51% in Oakland.)

Benefits not seen among Black youth

Despite the positive findings, researchers did not observe weight-related benefits among low-income or Black youth. Living in poorer environments may outweigh the possible beneficial effects of SSB taxes, suggested Monique M. Hedderson, PhD, MPH, of the Kaiser Permanente Northern California Division of Research.

“We need further studies to clarify who benefits most from these SSB taxes and why. It is especially important to understand why we did not see benefits among low-income and Black youth, Dr. Hedderson said. “It is possible that it may take a longer time to see the benefits of the health-related programs funded by these taxes.”

Study authors in addition to Dr. Young and Dr. Hedderson include Margo A. Sidell, ScD; Deborah A. Cohen, MD, MPH; Lee J. Barton, MS; Galina Inzhakova, MPH; Allison C. Voorhees, MPH; and senior author Bing Han, PhD, all of the Department of Research & Evaluation; Catherine Lee, PhD; Emily F. Liu, MPH; and Sneha Sridhar, MPH; of the Division of Research, Kaiser Permanente Northern California, and Jennifer Falbe, ScD, MPH, of the Department of Human Ecology, University of California, Davis.