Can Soda Taxes Curb Child Obesity?

New research shows children living in Seattle experienced a larger decrease in a body mass index measurement following the implementation of a so-called soda tax in the city compared with kids living in nearby nontaxed areas.

The analysis – published Wednesday in JAMA Network Open and thought to be among the first to indicate a tangible health benefit linked to such policies – evaluated changes in body mass index among more than 6,300 children between 2 and 18 years old. The children lived in urban areas of Seattle, surrounding King County or nearby Snohomish and Pierce counties, and had at least one weight measurement before and after Seattle’s excise tax on sugary beverages of 1.75 cents per ounce took effect in 2018.

Researchers found children in Seattle had a greater decrease in BMIp95 after the tax compared with children in neighboring areas. BMIp95 is a percentage that shows how a child’s body mass index value compares with the value of the 95th percentile – a threshold at which a child is classified as obese – for a reference group of children of the same age and sex.

The metric is “currently recommended for assessing changes in children’s BMI over time,” says lead study author Jesse Jones-Smith, a professor in the Department of Health Systems and Population Health at the University of Washington School of Public Health.

The study shows BMIp95 declined from 84% on average prior to the tax to 82% after its implementation among children living in Seattle, compared with a decline from 86% to 85% for children living in non-taxed areas.

Children in Seattle also saw larger BMIp95 reductions than those in the comparison area from before to after the tax’s implementation across many demographic groups, including boys and girls, Black and white children, and those in both high- and low-poverty neighborhoods, along with those who had either commercial or another type of insurance.