Estimating the effect on obesity of delaying tax-based interventions in Mexico: A modeling study

Background: The World Health Organization (WHO) launched the Acceleration Plan to STOP Obesity, highlighting the urgent need for timely implementation of proven interventions. Fiscal policies, including taxes on sugar-sweetened beverages (SSB) and non-essential energy-dense foods (NEDF), are among the most cost-effective strategies to reduce obesity rates. Delays in adopting or strengthening these measures can undermine their impact, and the consequences of postponing such policies remain unmeasured. We aimed to estimate the expected impact of delaying doubling the SSB and NEDF tax in Mexico. Methods and findings: We simulated a closed cohort of Mexican adults aged 20 years and over from 2021 to 2040. The simulated sample corresponded to the combination of the 2020−22 Health and Nutrition Surveys, which contained anthropometric and demographic information representative at a national level. We projected annual average Body Mass Index (BMI), obesity prevalence, deaths averted, and years lived without obesity (YLWO) under four scenarios: status quo and doubling the current tax on SSB and NEDF in 2025, 2030, and 2035. BMI was projected from 2021 to 2040 using Hall’s microsimulation weight change model, and a Mexican projection of total energy intake. To simulate deaths, we estimated the probability of all-cause mortality by BMI category from the National Population Council projections of the Mexican population by age and year. By 2040, doubling the taxes in 2025 resulted in an obesity prevalence of 41.6% (95% Uncertainty Interval [40.2,43.1]) in contrast to the status quo scenario (44.5%, 95% Uncertainty Interval [43.2,45.8]), and 170,600 deaths averted (95% Uncertainty Interval [130,900, 210,200]) and 25,031,900 (95% Uncertainty Interval [19,048,500, 31,015,300]) YLWO gained. A delayed intervention in 2035 resulted in an obesity prevalence of 41.7% (95% Uncertainty Interval [40.4,43.1]), 38,900 deaths averted (95% Uncertainty Interval [29,600, 48,200]), and 4,473,700 (95% Uncertainty Interval [3,378,900, 5,568,500]) YLWO gained. Our results apply only to individuals aged 20 years or older in 2021, excluding cohorts reaching age 20 between 2022 and 2040. Conclusions: Our results emphasize the urgency of advancing WHO’s Acceleration Plan to STOP Obesity. Postponing evidence-based interventions is estimated to exacerbate the burden of obesity, mortality, and suffering. Why was this study done?: What did the researchers do and find?: What do these findings mean?: In a modelling study, Martha Carnalla and colleagues investigate the effects doubling the current tax on sugar-sweetened beverages and non-essential energy-dense foods would have on obesity levels, by simulating a closed cohort of Mexican adults.