Chile’s groundbreaking nutrition regulations, which prohibit food companies from marketing unhealthy foods to kids and require stop-sign-shaped labels on sugary, salty, and fatty foods, did not reduce obesity rates among elementary and high school students in a lasting way, according to a new study.
The researchers, who described these findings as “disheartening,” reported that obesity rates for younger children, in prekindergarten to first grade, did show an initial drop of 1 to 3 percentage points one year after the regulations took effect in 2016. But by 2018, those rates had rebounded to pre-reform levels.
The picture for teenagers was even worse. Among ninth graders, the prevalence of obesity and overweight continued to rise in the three years after the regulations took effect, according to the study, which was published in the Pan-American Journal of Public Health earlier this month.
The researchers compared the results to the yo-yo effect that almost anyone who’s ever dieted knows well — one may lose weight at first, only to see that progress stall or reverse. “What’s shocking here is to see that happen to a whole country’s children,” said Paul von Hippel, a coauthor of the paper and a professor at the University of Texas, Austin’s Lyndon B. Johnson School of Public Affairs. “Either children’s metabolisms slowed to match their new diets, or children and parents figured out a way to eat as many calories as before, despite changes in food content and advertising,” he said in a news release.
Chile’s laws, passed despite staunch industry opposition, have served as a model for other countries looking to curb obesity rates, including Peru, Uruguay, Argentina, Mexico, and Israel.
Previous research suggests that Chile’s reforms have had a number of positive effects, the researchers noted. One study found that the energy, sugar, sodium, and saturated fat content of foods and drinks served at schools, advertised on TV, and bought in grocery stores declined substantially after the regulations took effect. Another reported that consumers bought fewer products labeled with stop signs once the front-of-package labels became law. The regulations also prompted some food processors to stop using toys and advertising with cartoon characters; others reformulated their products to squeak under the thresholds that would have required them to label their products.
The researchers offered a few theories for why obesity rates did not decline. Children and adolescents may have increased portion sizes of junk foods, started eating more often, begun adding sugar to foods, or started bringing more food from home to school, the researchers wrote.
They also offered ideas for how Chile’s campaign, and others like it, might be made more effective. Campaigns could better target their messaging to teenagers, they wrote. And instead of focusing on fat, salt, sugar, and calories, the regulations could take a broader approach by encouraging the consumption of whole fiber and discouraging the consumption of refined carbohydrates overall, or by steering consumers away from processed foods altogether and promoting whole foods.