A package of food policies introduced in Chile was linked to a modest decline in the likelihood that young children would have overweight or obesity, according to a large observational study published in The Lancet.
The study does not prove that the law caused the change. However, researchers found evidence suggesting that the coordinated policies may have made a measurable difference at the population level. The findings are notable because the law did not rely on a single approach. It combined front-of-package warning labels, restrictions on certain foods sold in schools and limits on marketing directed at children.
Chile introduced the first phase of its Food Labelling and Advertising Law in 2016. Foods and drinks high in sugars, saturated fats, sodium or calories were required to display black octagonal warning labels on the front of the package. Products that met those criteria were also restricted in schools and subject to limits on child-directed marketing.
Researchers analyzed national data from more than 300,000 children ages 4 to 6. They compared children in the same school grades before and after the first phase of the law took effect.
After 18 months, girls exposed to the law had a 2.9% lower relative risk of overweight or obesity than girls in the same grades before the policy was introduced. For boys, the relative risk was 2.4% lower.
In absolute terms, the changes were smaller but still measurable. Among girls, the prevalence of overweight or obesity declined by 1.4 percentage points from a pre-policy rate of 47.7%. Among boys, it declined by 1.2 percentage points from a pre-policy rate of 52%.
Researchers also identified changes after only six months. Girls had a 1.9% lower relative risk of overweight or obesity, representing a reduction of 0.9 percentage points. Boys had a 2.2% lower relative risk, representing a reduction of 1.2 percentage points.
The results may sound modest, particularly when viewed at the individual level. Across an entire population, however, even a small shift can affect a meaningful number of children.
“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 Prof. Guillermo Paraje of Universidad Adolfo Ibáñez Business School in Chile.
The study is especially relevant because families do not make food choices in isolation. Children encounter food marketing, packaging, school meals, vending options, store displays and other influences throughout the day. The Chilean law sought to change several parts of that environment at once.
The findings do not reveal which part of the policy package mattered most. Researchers could not determine whether the changes were primarily connected to warning labels, school food rules, advertising restrictions or the combined effect of all three.
The study also cannot rule out every possible explanation for the shift. Researchers used a difference-in-differences design, a method commonly used to evaluate policies when randomized trials are not practical. The analysis relies on the assumption that children’s weight trends would have continued along similar paths if the law had not been introduced. The researchers examined trends before the policy took effect to support that assumption, but it cannot be tested with certainty.
Another limitation is that children’s height and weight were recorded by trained school staff rather than measured in health care settings, which may have introduced some imprecision.
The study evaluated only the first phase of the law. Chile introduced stricter thresholds for sugars, saturated fats, sodium, and calories in 2018 and 2019. Those later phases were not included in the analysis.
The researchers noted that earlier studies have found changes in purchases of foods and drinks affected by the law. The latest findings take the research a step further by examining whether the coordinated policies may also be linked to a measurable health outcome among children.
The study does not suggest that food labels alone can solve childhood obesity, a complex issue influenced by many factors. It does offer evidence that policies designed to make the food environment easier to navigate may contribute to meaningful changes over time.
“Although the reduction in obesity and overweight risk among young school children may seem modest, it is likely that the further tightening of the law in later years will have increased the impact,” said Dr. Nieves Valdes of Universidad Adolfo Ibáñez Business School.
The study was funded by a Bloomberg Philanthropies grant.