“The world has failed to protect its children,” laments Alexandre Hohl, MD, endocrinologist and director of the Brazilian Association for the Study of Obesity and Metabolic Syndrome (ABESO). The data from the World Obesity Atlas 2026, prepared by the World Obesity Federation (WOF), show that the rise in cases has moved from a trend to an established reality.

Atlas Findings 2026

“Today, more than 1 in 5 young people (20.7%) live with overweight or obesity, and in Brazil, there are already about 17 million children and adolescents in this condition,” said the expert.

Projections indicate that, by 2040, that number will reach 507 million worldwide. Of that total, at least 120 million children and adolescents are estimated to show early signs of chronic disease before adulthood.

The figures released by WOF on World Obesity Day indicate that the 2025 global target to halt the rise of obesity in children and adolescents was not met and that most countries remain off track even with the deadline extended to 2030.

“The rise in childhood obesity around the world shows we failed to take seriously a disease that affects 1 in 5 children,” Johanna Ralston, CEO of WOF, said in a public statement.

Brazil’s Burden Now

In Brazil, the picture follows the global trend. The country ranks among the 10 countries with the largest absolute number of children and adolescents living with elevated BMI, with millions already showing established obesity. National estimates for 2025 show the problem is broadly distributed across childhood and adolescence: approximately 6.6 million children aged 5-9 years and 9.9 million adolescents aged 10-19 years live with overweight or obesity in the country.

Data from the Food and Nutritional Surveillance System indicate that excess weight in Brazil already appears even before birth. Among pregnant women followed in the public health network, 58.8% have excess weight. In early childhood (age 0-5 years), 7% of children already have a weight that is high for their age, a figure that jumps to 35.7% in adolescence. In adulthood, 73.6% are overweight.

Early Life Trends

In Latin America, the situation is equally alarming. Chile ranks among the countries with the highest proportional prevalence of overweight in school-age individuals, with more than 60% of children and adolescents aged 5-19 years living with elevated BMI. The Americas have one of the highest global prevalences of childhood obesity, which is expected to continue growing through 2040.

Historical transition “Obesity does not begin in adulthood but is formed over a lifetime,” summarized Bruno Halpern, endocrinologist, president of ABESO, and vice president of WOF. The statement, made in a press release, echoes the historical transition described in the Atlas: This decade, the number of children and adolescents with obesity is expected, for the first time, to exceed the number of underweight children.

That reversal aligns with data from the NCD Risk Factor Collaboration, which in 2017 already demonstrated a continuous rise in obesity among school-age children over recent decades. The Atlas projects that the global prevalence of obesity in children and adolescents aged 5-19 years will rise from 8.7% in 2025 to 11.9% in 2040.

Globally, 177 million children and adolescents lived with obesity in 2025; that number is expected to reach 228 million in 2040. When overweight and obesity are considered together, prevalence rose from 14.6% in 2010 to 20.7% in 2025.

Clinical Consequences Emerging

More worrying than prevalence are the metabolic consequences already present. Millions of children and adolescents show early signs of chronic disease before adulthood. Hohl warned that the impact goes far beyond statistics.

“We are projecting a generation increasingly exposed to hypertension, elevated glucose, and liver disease associated with high BMI. If nothing changes structurally — through fiscal policies, regulation of marketing, and effective promotion of physical activity — we are heading toward normalizing that millions of Brazilian children will develop, already in adolescence, chronic diseases we once saw only in adults,” the specialist told Medscape Medical News.

In Brazil, the most recent estimates indicate that about 1.4 million children live with hypertension attributable to elevated BMI, 572,000 live with hyperglycemia, about 1.8 million live with hypertriglyceridemia, and about 4 million with metabolic dysfunction-associated fatty liver disease. These projections are for 2025.

These figures are reflected in pediatric clinics, where monitoring for hypertension, insulin resistance, and fatty liver is taking place at increasingly younger ages — a reality that mirrors the structural change described in the global data.

Policy Failures, Clinical Impact

The persistence of the problem is directly linked to the continued presence of widely known risk factors. Today, 95% of countries report high levels of inadequate breastfeeding, 95% report a high proportion of adolescents who do not meet minimum physical activity recommendations, and 74% report excessive consumption of sugar-sweetened beverages — three of the main modifiable determinants of early weight gain.

Although Brazil has structured policies on school feeding and national physical activity guidelines, important gaps remain, particularly in large-scale implementation, enforcement, and continuous monitoring of actions.

The problem, therefore, is not only the absence of rules but also the difficulty of transforming them into consistent environmental change.

Childhood obesity cannot be treated as a distant risk. The Atlas itself reinforces that millions of children are already showing early signs of chronic disease attributable to elevated BMI. Studies show that childhood obesity significantly increases the likelihood of persistent obesity into adulthood and the early risk for type 2 diabetes and cardiovascular disease.

Policy and Practice

In response, the WOF advocates combined structural measures such as taxes on sugar-sweetened beverages, restrictions on marketing of unhealthy foods aimed at children, protection of breastfeeding, and strengthening primary care as part of a coordinated response. The 2026 report makes clear that the nutritional transition has already occurred; what is now at stake is whether Brazil and the rest of the world can turn this global failure into effective action before an entire generation carries the consequences of obesity into adulthood.

Daniela Barros is a journalist from Brazil, specializing in social journalism at the Pontifical Catholic University of São Paulo in São Paulo, and a master’s student in the Department of Social Medicine at the Ribeirão Preto Medical School in Ribeirão Preto, Brazil. She has been involved in medicine for 23 years and has contributed to several specialized publications.

This story was translated from Medscape’s Portuguese edition.