Overweight, Obesity, and Growth Faltering Among Low-Income Children in Brazil.

IMPORTANCE

Nutritional status is a key determinant of child health. While undernutrition and stunting persist among vulnerable populations, overweight and obesity have emerged as growing public health concerns. Quantifying these conditions across subpopulations is essential for guiding interventions.

OBJECTIVE

To describe and compare height-for-age and body mass index (BMI)-for-age adequacy, including the prevalence of overweight, obesity, and stunting, among low-income children in Brazil by region, age, sex, and ethnoracial group.

DESIGN, SETTING, AND

PARTICIPANTS

This cohort study used administrative health records of 6 494 753 Brazilian children aged 0 to 10 years who were born between January 1, 2001, and December 31, 2015, and were enrolled in the public primary health care system. Data were obtained from 3 administrative databases-the Unified Registry, Live Birth Information System, and Food and Nutrition Surveillance System-and evaluated at 9 years of age until December 31, 2018. Descriptive statistics were used to summarize baseline characteristics, and prevalence estimates were presented with SEs. Data were analyzed from December 1, 2024, to June 31, 2025.

EXPOSURE: Demographic characteristics (age, sex, and ethnoracial group) and geographic region of residence.

MAIN OUTCOMES AND MEASURES: Anthropometric adequacy was assessed using height-for-age and BMI-for-age z scores, classified according to World Health Organization standards. Outcomes included the prevalence of stunting (height-for-age z scores less than -2), overweight (BMI-for-age z scores greater than 1), and obesity (BMI-for-age z scores greater than 2), reported overall and by subgroups.

RESULTS

Among the 6 494 753 million children, 51.48% were female, with a mean (SD) age of 3.6 (2.8) years. In terms of race and ethnicity, 0.26% were Asian; 3.84%, Black; 0.90%, Indigenous; 61.71%, Parda; and 28.72%, White; 4.57% had missing or inconsistent data. Overall, 433 754 children (6.68%) experienced stunting, 818 967 (12.61%) had overweight, and 489 541 (7.54%) had obesity. Estimated obesity prevalence (SE) at 5 years of age was 8.48% (0.02%), increasing to 10.09% (0.05%) at 9 years of age. Obesity was more frequent boys (14.12% [0.12%]) than girls (10.09% [0.05%]) at 9 years of age. Among girls, obesity prevalence (SE) was 11.8% (0.09%) among those who identified as White, 9.12% (0.06%) among those who identified as Parda, and 7.46% (0.48%) among those who identified as Indigenous.

CONCLUSIONS AND RELEVANCE: This large-scale cohort study highlights persistent regional and ethnoracial disparities in both growth faltering and excess weight gain. The coexistence of undernutrition and obesity in the same population underscores the urgency for targeted nutrition and health policies in early childhood.