Landmark study in Chile shows food policies can reduce childhood obesity - here’s what it means for the world
A major new study published in The Lancet provides the strongest evidence yet that a package of legally mandated food environment policies can, together, measurably reduce rates of childhood overweight and obesity.
The findings have significant implications for governments worldwide.
What the research found
Researchers analysed data from more than 300,000 Chilean schoolchildren aged four to six, comparing weight outcomes before and after Chile's Food Labelling and Advertising Law (FLAL) came into force in 2016.
The FLAL is one of the most comprehensive food environment laws ever implemented. It introduced three interlocking measures targeting foods and drinks high in sugar, saturated fat, salt or calories:
- Mandatory front-of-package warning labels in the form of bold black octagonal symbols
- Restrictions on the sale of those products in schools
- Limits on food marketing directed at children
Using a quasi-experimental design - tracking cohorts of children through school grades before and after the policy - the study found that children exposed to the law for 18 months were less likely to be living with overweight or obesity than children of the same age before the law was introduced. Girls saw a 2.85% reduction in the probability of excess weight; boys saw a 2.40% reduction.
Even after just six months of exposure, significant reductions were observed.
This is the first study to provide plausible causal evidence, at national scale, that a combined package of food policies - not a single measure in isolation - reduces childhood excess weight.
Why this matters
For years, advocates and researchers have argued that tackling childhood obesity requires action across the whole food environment, not just one lever pulled at a time. Sugar taxes, school food standards, advertising restrictions and front-of-pack labelling have each been studied individually, but until now there has been no real-world national evidence that they work together to shift population-level weight outcomes in children.
The lead author, Prof Guillermo Paraje of Universidad Adolfo Ibáñez, Chile, said the results "offer strong evidence for policymakers around the world," adding that they "support mandatory front-of-pack nutrition warning labels, restrictions on unhealthy food in schools, and marketing bans as effective, practical ways to tackle the childhood obesity epidemic."
Commentators writing in The Lancet alongside the paper noted that the findings "strengthen the case for governments to move beyond incremental, single-policy approaches and to instead implement comprehensive, integrated strategies to improve food environments."
READ THE STUDY
Johanna Ralston, CEO of the World Obesity Federation, said: "This study provides some of the clearest evidence to date that comprehensive food policies can make a meaningful difference to children's health. Too often, policy discussions focus on individual measures in isolation, but Chile's experience shows that coordinated action across labelling, marketing and school food environments can help create healthier conditions for children and families.
There is no single cause of obesity, and no single solution. Governments need comprehensive policy packages that address the environments shaping health while also ensuring access to prevention, treatment and long-term care. This study offers an important example of what can be achieved when evidence-based policies work together."
Putting the numbers in context
A 2.40-2.85% lower probability of excess weight might appear modest at first glance. But context matters.
These reductions represent a meaningful shift in risk across the entire population. Children living with obesity face substantially elevated risks of obesity in adulthood, as well as type 2 diabetes, hypertension and cardiovascular disease. Even modest reductions in childhood excess weight, if sustained, translate into significant population-level health gains over decades.
Crucially, the study only captures Phase 1 of the FLAL, using data up to 2017. Phases 2 and 3, introduced in 2018 and 2019, tightened thresholds further and have been associated with even larger reductions in purchases of regulated foods. The full impact of the law is almost certainly greater than what this study could measure.
Equity considerations
The benefits of the policy were not felt equally across all groups. Effects were stronger among children attending subsidised (rather than state) schools, those in urban areas, and those whose mothers had completed at least secondary education. Children whose mothers had not completed secondary school, and those in rural settings, showed smaller or non-significant effects.
This underscores the importance of complementary action: targeted communication for households with lower health literacy, stronger integration of food policy with school meal programmes in state schools, and specific attention to rural food environments.
The findings also showed a particularly strong protective effect for girls born with low birthweight - a biologically vulnerable group - suggesting that food environment policies may offer important benefits for those at greatest nutritional risk.
read the study
What this means for policymakers worldwide
Dozens of countries have now adopted front-of-package warning labels, and many more are actively considering marketing restrictions and school food standards, as part of the WHO Acceleration Plan This new evidence from Chile helps advocates strengthen the case to policymakers worldwide.
Writing in a linked comment in The Lancet, researchers from the George Institute for Global Health noted that the findings "strengthen the case for governments to move beyond incremental, single-policy approaches and to instead implement comprehensive, integrated strategies to improve food environments."
The study's authors are equally direct: the results "provide crucial evidence-based support for policy makers worldwide who are considering food environment policies as a scalable, impactful strategy to combat the childhood obesity epidemic."
For governments at any stage of food policy development - whether considering a first front-of-pack label, strengthening existing school food rules, or designing a comprehensive package - the Chilean experience offers a clear template: the measures reinforce one another, and the combination is what drives population-level change.
About the study
The study - "The impact of Chile's multipronged food labelling and advertising law on early childhood excess weight: a cohort difference-in-differences study" - was conducted by researchers at Universidad Adolfo Ibáñez, the University of Chile and the University of North Carolina. It is published in The Lancet and was funded by Bloomberg Philanthropies.
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