A CHOICES study analyzed changes in childhood obesity prevalence among children participating in WIC both before and after food package changes were enacted in 2009, and found that obesity prevalence among children participating in WIC has been decreasing since the 2009 changes.
Daepp MIG, Gortmaker SL, Wang YC, Long MW, Kenney EL. WIC Food Package Changes: Trends in Childhood Obesity Prevalence. Pediatrics. 2019;143(5):e20182841.
The aim of this study was to evaluate if the changes made to the foods that could be purchased through the U.S. Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) in 2009 had an impact on childhood obesity.
In 2009, the lists of foods that could be purchased with WIC vouchers (known as the WIC food packages), which includes basic food categories, were updated to better align with the Dietary Guidelines for Americans. The new package, still in use today, provided extra cash allowances for fruits and vegetables, cut the previous juice allowance in half, required low-fat or skim milk for 2-4 year olds, reduces cheese, and required whole-grain instead of refined-grain products (among other changes).
Earlier studies showed that this shift had resulted in significant changes in WIC participants’ diets and in lowering the amount of calories they consumed. The Centers for Disease Control showed that there had been some declines in childhood obesity prevalence among WIC participants in recent years.1 However, there had not yet been a direct test of whether the WIC package change may have catalyzed a turn-around in childhood obesity rates among WIC participants.
Using state-specific obesity prevalence data for 2-4 year olds participating in WIC from 2000 to 2014, the researchers estimated the annual trend in obesity prevalence across states, and then tested whether that trend significantly changed after the WIC package revision in 2009, adjusting for changes in demographics.
The researchers found that, before the 2009 WIC food package change, the prevalence of obesity across states among 2-4 year olds participating in WIC was growing 0.23 percentage points annually. However, after 2009, this alarming trend switched direction. Instead, the prevalence of obesity across states among 2-4 year olds participating in WIC started decreasing by 0.34 percentage points annually.
“Our study suggests that, in addition to its critical role in reducing the burden of food insecurity and improving nutrition among young children in low-income families, WIC also can help promote healthy weight,” says co-author Erica Kenney, CHOICES Co-Investigator and Professor of Public Health Policy in the Department of Health Policy and Management at the Harvard T.H. Chan School of Public Health. “This is especially encouraging given that over half of all infants born in the U.S. are eligible for the program – there is a real opportunity here to have a positive impact on childhood obesity.”
These results suggest that the 2009 WIC food package change likely helped to reverse the rapid increase in obesity prevalence among WIC participants observed before the food package change, helping set the millions of young children who benefit from WIC on a path toward a healthier weight.
References
- Pan L, Freedman DS, Sharma AJ, Castellanos-Brown K, Park S, Smith RB, Blanck HM. Trends in Obesity Among Participants Aged 2-4 Years in the Special Supplemental Nutrition Program for Women, Infants, and Children – United States, 2000-2014. MMWR Morb Mortal Wkly Rep. 2016 Nov 18;65(45):1256-1260. doi: 10.15585/mmwr.mm6545a2


Since the cost of a sugary drink excise tax is incorporated directly into the beverage’s sticker price, an excise tax will likely influence consumer purchasing decisions more than a comparable sales tax that is added onto the item at the register. We assume 100% pass-through of the tax over 10 years and assume the tax rate would be adjusted annually for inflation. Our pass-through rate estimate is supported by empirical studies of excise taxes in Mexico and France that demonstrate near-complete pass through rates to consumers.24 Short term studies for the local tax in Berkeley indicate imperfect, or less than 100%, pass-through.3,25,26 The expected change in sugary drink price was estimated using an average of $0.06/ounce based on national sugary drink prices.27 The price per ounce in this study was based on a weighted average of sugary drink consumption across stores, restaurants and other sources according to the estimates from the National Health and Nutrition Examination Survey (NHANES) 2009-2010. The price per ounce of sugary drinks purchased in stores was calculated using weighted averages of two-liter bottles, 12-can cases, and single-serve containers based on 2010 Nielsen Homescan data.27 For example, a $0.02/ounce tax would raise the price of a 12-ounce can of soda from $0.72 to $0.96/can post-tax.
How does an excise tax on distributors affect the price paid by consumers?










Sugary drinks include all beverages with added caloric sweeteners. The modeled excise tax does not apply to 100% juice, milk products, or artificially-sweetened beverages. Although sugary drinks consumption has declined in recent years, adolescents and young adults in the United States consume more sugar than the Dietary Guidelines for Americans recommend, with persistent racial/ethnic disparities.5-8 Randomized trials and longitudinal studies have linked sugary drinks consumption to excess weight gain, diabetes, and cardiovascular disease. Consumption of sugary drinks increases the risk of chronic diseases through its impact on weight and other mechanisms.9,10 The Dietary Guidelines for Americans, 2015-202011 recommend that individuals reduce sugary drink intake in order to manage their body weight. Drawing on the success of tobacco taxation and decades of economic research, public health experts have studied taxes on sugary drinks and documented their likely impact.12-15 In 2009, the IOM recommended that local governments implement tax strategies to reduce consumption of “calorie-dense, nutrient-poor foods,” emphasizing sugary drinks as an appropriate target for taxation.16





SSBs include all beverages with added caloric sweeteners. The modeled excise tax does not apply to 100% juice, milk products, or artificially-sweetened beverages. Although sugary drinks consumption has declined in recent years, adolescents and young adults in the United States consume more sugary drinks than the Dietary Guidelines for Americans recommends, with persistent racial/ethnic disparities.5-8 Randomized trials and longitudinal studies have linked SSB consumption to excess weight gain, diabetes, and cardiovascular disease. Consumption of SSBs increases the risk of chronic diseases through its impact on BMI and other mechanisms.9,10 The Dietary Guidelines for Americans, 201511 recommends that individuals reduce SSB intake in order to manage their body weight. Drawing on the success of tobacco taxation and decades of economic research, public health experts have called for higher taxes on SSBs and documented their likely impact.12-15 In 2009, the IOM recommended that local governments implement tax strategies to reduce consumption of “calorie-dense, nutrient-poor foods,” emphasizing SSBs as an apt target for taxation.16








Impact of Tax on Price to Consumers
