Predicting obesity reduction after implementing warning labels in Mexico: A modeling study.

Background In October 2019, Mexico approved a law to establish that nonalcoholic beverages and packaged foods that exceed a threshold for added calories, sugars, fats, trans fat, or sodium should have an "excess of" warning label. We aimed to estimate the expected reduction in the obesity prevalence and obesity costs in Mexico by introducing warning labels, over 5 years, among adults under 60 years of age. Methods and findings Baseline intakes of beverages and snacks were obtained from the 2016 Mexican National Health and Nutrition Survey. The expected impact of labels on caloric intake was obtained from an experimental study, with a 10.5% caloric reduction for beverages and 3.0% caloric reduction for snacks. The caloric reduction was introduced into a dynamic model to estimate weight change. The model output was then used to estimate the expected changes in the prevalence of obesity and overweight. To predict obesity costs, we used the Health Ministry report of the impact of overweight and obesity in Mexico 1999-2023. We estimated a mean caloric reduction of 36.8 kcal/day/person (23.2 kcal/day from beverages and 13.6 kcal/day from snacks). Five years after implementation, this caloric reduction could reduce 1.68 kg and 4.98 percentage points (pp) in obesity (14.7%, with respect to baseline), which translates into a reduction of 1.3 million cases of obesity and a reduction of US$1.8 billion in direct and indirect costs. Our estimate is based on experimental evidence derived from warning labels as proposed in Canada, which include a single label and less restrictive limits to sugar, sodium, and saturated fats. Our estimates depend on various assumptions, such as the transportability of effect estimates from the experimental study to the Mexican population and that other factors that could influence weight and food and beverage consumption remain unchanged. Our results will need to be corroborated by future observational studies through the analysis of changes in sales, consumption, and body weight. Conclusions In this study, we estimated that warning labels may effectively reduce obesity and obesity-related costs. Mexico is following Chile, Peru, and Uruguay in implementing warning labels to processed foods, but other countries could benefit from this intervention. Author summaryWhy was this study done? In October 2019, the Mexican government approved new warning labels for packaged food and nonalcoholic beverages. Products that exceed a certain limit of calories, sugars, fats, trans fats, or sodium will now have a black octagon with an "excess of" label. Estimating the impact of these labels is necessary to translate this effort into expected reductions in intake and potential changes in body weight, obesity prevalence, and healthcare cost reductions. What did the researchers do and found? Adults in Mexico consume approximately 31% of their total energy intake from beverages and snacks. This study found that warning labels could reduce on average 36.8 kcal/person/day (23.2 kcal from beverages and 13.6 kcal from snacks). Using a mathematical model, we translated the expected caloric change into expected changes in body weight and obesity prevalence. Five years after the warning label implementation, obesity prevalence could be reduced by 14.7%, with respect to baseline, translating into 1.30 million cases of obesity reduced. Larger effects will be expected among males, young adults, and the middle and high socioeconomic status (SES) group. After five years, warning labels could save an estimated US$1.8 billion on obesity costs. Our model has some important limitations, such as using a Canadian estimate of the effect of warning labels. To capture a wider scope of effects, we used studies from Chile and Uruguay, which produced larger effects than the Canadian-based scenario. What do these findings mean? Warning labels have the potential to reduce the intake of nonessential high caloric food, reduce obesity, and lead to healthcare cost savings in Mexico. Warning labels could be considered by other countries with similar conditions, as part of their obesity control packages. These projections will need to be confirmed by future studies analyzing the change in food and beverage consumption and body weight after the implementation of the new warning labels.