Food labels, ad ban combo led to lower child obesity

Clinical takeaway: Comprehensive food environment policies, not just single measures, may meaningfully shift childhood weight at the population level, though benefits remain concentrated among families with more advantages.

Childhood obesity trends have been resistant to effective intervention. A 2016 food law in Chile bundled multiple, staged approaches, gaving researchers a national-scale natural experiment. This is the first national-level data to show that bundling related measures may outperform single-policy approaches like soda taxes.

Chile ranks among the world's highest countries for childhood excess weight. More than half of the schoolchildren were overweight or obese. In response, the country rolled out its Food Labelling and Advertising Law in phases starting in 2016, requiring black octagonal "high in" warnings on products heavy in sugar, saturated fat, sodium, or calories, barring their sale in schools, and curbing marketing aimed at children. Thresholds tightened in later phases in 2018 and 2019 with further limits on sugar, saturated fat, salt, and calories, but that fell outside the study window.

Among more than 320,000 children aged four to six, those exposed to the law's initial phase were less likely to carry excess weight than peers in the same grades before it was implemented. After 18 months of exposure, boys had a 2.4% lower probability of overweight or obesity and girls a 2.85% lower probability. Shorter exposure of about six months showed similar reductions, 2.24% in boys and 1.91% in girls.

The estimates for boys rested on firmer ground. Pre-policy weight trends ran parallel between exposed and unexposed groups, supporting the causal read. For girls, that check was less reassuring, and the authors caution that the female estimates should be interpreted more tentatively.

Benefits were uneven. Reductions concentrated among children in subsidized and urban schools and those whose mothers had at least a high school education. Effects weren't significant in rural areas, in public schools, or among children whose mothers had not finished high school.

Researchers used a cohort difference-in-differences design, comparing children who entered prekindergarten before the law (2012 and 2013) with cohorts exposed during early school years (2014 and 2015). Weight and height came from Chile's national school nutrition records, linked to a vulnerability survey for maternal and birth data. Only phase 1 of the law was captured; stricter thresholds added in 2018 and 2019 fell outside the window.

Initial results are likely a floor, not a ceiling. The stricter thresholds added in 2018 and 2019 and the longer exposure they allow fell outside this analysis, and the authors expect larger effects as those take hold. Whether the early weight reductions persist into adolescence, and whether the gap between advantaged and underserved families narrows or widens as the policy matures, remains to be seen.

“Although individual national measures like sugar taxes on soft drinks have been associated with improved health outcomes, this is the first study to plausibly demonstrate that a package of policies can reduce early childhood overweight/obesity risk at the national level," said Guillermo Paraje, DPhil, professor of economics at the Universidad Adolfo Ibáñez Business School in Chile.

Source: Paraje G. Lancet. 2026 Jun 11. The impact of Chile's multipronged food labelling and advertising law on early childhood excess weight: a cohort difference-in-differences study