Novo Nordisk Reports Positive Phase 3 STEP Young Results for Semaglutide in Children With Obesity
Novo Nordisk has announced the first results from the STEP Young Phase 3 trial evaluating once-weekly semaglutide in children aged 6 to under 12 years living with obesity. The study assessed semaglutide in combination with lifestyle modifications, including a reduced-calorie diet and increased physical activity, in a pediatric population for whom treatment options remain limited when lifestyle changes alone are insufficient.
The trial met its primary endpoint, demonstrating a superior reduction in body mass index (BMI) at week 68 among children treated with semaglutide compared with those receiving placebo. Importantly, the results also showed that 40.4% of children treated with semaglutide were no longer classified as having obesity at week 68, compared with none of the children receiving placebo.
According to Novo Nordisk, the findings mean that approximately two out of every five children receiving semaglutide reduced their BMI sufficiently to move below the obesity threshold into either a normal-weight or overweight BMI classification, while no children in the placebo group achieved this outcome.
Both treatment groups received lifestyle intervention throughout the trial, meaning the results reflect the potential effect of adding once-weekly semaglutide to reduced-calorie dietary intake and increased physical activity.
STEP Young Addresses a Significant Pediatric Obesity Need
Childhood obesity represents an increasing public health challenge, particularly because excess weight during childhood can persist into adulthood and is associated with a range of health and psychosocial complications.
The STEP Young trial focused on children between 6 and under 12 years of age, an age group in which there are limited clinically tested and approved pharmacological treatment options for obesity. The need for additional approaches is particularly important for children whose obesity does not improve sufficiently through lifestyle modifications alone.
At the beginning of the STEP Young trial, more than 85% of participating children were classified as having either class II or class III severe obesity. These classifications correspond to BMI thresholds of at least 35 and 40, respectively, when using adult BMI definitions.
The high level of severe obesity among participants highlights the medical needs of the population evaluated in the study. Novo Nordisk said the positive results indicate that semaglutide may have the potential to provide an additional treatment option for children with obesity who require medical intervention alongside lifestyle changes.
Ania M. Jastreboff, MD, PhD, Professor of Medicine in Endocrinology and Pediatrics in Pediatric Endocrinology at Yale and Director of the Yale Obesity Research Center, emphasized the importance of addressing obesity early in life.
“Childhood obesity is particularly concerning due to both immediate and enduring impacts on health, including a strong predilection to adult obesity and increased risk for the early emergence of obesity-related complications,” Jastreboff said.
She added that most children enrolled in STEP Young had severe class II or III obesity at baseline, while semaglutide treatment resulted in approximately 40% of participants reaching a BMI percentile category below the obesity threshold after about one year of treatment.
Primary Endpoint Successfully Achieved
The STEP Young Phase 3 trial achieved its primary endpoint, showing a greater reduction in BMI at week 68 in children receiving once-weekly semaglutide compared with children receiving placebo.
In addition to the primary BMI outcome, the proportion of children who moved below the obesity classification provides an important measure of the potential clinical impact of treatment.
At week 68, 40.4% of children treated with semaglutide were no longer classified as having obesity, while the corresponding proportion in the placebo group was 0%.
The result is notable because both groups received lifestyle modifications during the study. Participants were supported in following a reduced-calorie diet and increasing physical activity, meaning semaglutide was evaluated as an addition to lifestyle intervention rather than as a replacement for behavioral and dietary measures.
The findings suggest that combining pharmacological treatment with lifestyle changes may help some children achieve clinically meaningful improvements in BMI when lifestyle modifications alone do not produce sufficient results.
The company said detailed findings from STEP Young will be presented at The Obesity Society’s annual meeting, ObesityWeek 2026, scheduled for November 14–17 in Washington, D.C., United States.
Childhood Obesity Linked to Long-Term Health Risks
The growing prevalence of obesity among children has increased concern about the long-term consequences of the disease. Children living with obesity can experience risk factors associated with cardiovascular disease, as well as mental and psychosocial challenges.
These challenges can include depression, eating disorders and bullying. Research cited by Novo Nordisk has also indicated that quality of life among children living with obesity can be comparable to that reported by children undergoing cancer treatment.
The consequences can extend well beyond childhood. Obesity during childhood is strongly associated with obesity in adulthood, while obesity-related complications can emerge earlier and may be more severe.
Novo Nordisk cited estimates indicating that approximately 177 million children between the ages of 5 and 19 were living with obesity globally in 2025. That number is projected to increase to approximately 228 million by 2040.
The company said these trends reinforce the importance of identifying effective interventions for children and adolescents living with obesity, particularly those with more severe disease.
Semaglutide Safety Profile Consistent With Previous Trials
Novo Nordisk reported that the overall safety and tolerability profile observed with semaglutide in STEP Young was consistent with previous pediatric and adult clinical trials involving semaglutide and liraglutide.
No new safety concerns were identified in the trial, according to the company. In addition, Novo Nordisk reported that there were no safety concerns identified in relation to growth or pubertal development.
Monitoring growth and development is particularly important when evaluating obesity medicines in children. Pediatric clinical development programs must consider not only changes in body weight and BMI but also whether treatment has any effect on normal growth trajectories and pubertal development.
The reported absence of new safety concerns in these areas is therefore an important component of the STEP Young findings. Further details from the trial are expected when the complete results are presented at ObesityWeek 2026.
Novo Nordisk Highlights Potential Role in Pediatric Obesity Care
Martin Holst Lange, executive vice president, chief scientific officer and head of Research & Development at Novo Nordisk, said the company views the findings as encouraging for children and families affected by obesity.
“For children living with obesity and their families, health challenges can begin early and affect wellbeing throughout life,” Lange said.
He described Novo Nordisk as a pioneer in pediatric obesity medicine and said the company was encouraged by the positive STEP Young results and the potential of semaglutide to help children who need medical treatment alongside lifestyle changes.
According to Lange, effective intervention could potentially help reduce the risk of serious health consequences later in life.
The results also add to Novo Nordisk’s broader clinical development program investigating GLP-1-based treatments across different age groups and obesity populations. While adult obesity treatment has received substantial attention in recent years, the STEP Young results focus on a younger population where treatment needs and clinical considerations are distinct.
Potential Significance for Pediatric Obesity Treatment
The STEP Young findings could be significant because childhood obesity often requires a long-term approach involving dietary, physical activity, behavioral and, when appropriate, medical interventions.
The fact that more than 85% of participants entered the trial with class II or III severe obesity underscores the severity of disease among the children studied. The reduction in BMI and movement below the obesity classification observed in 40.4% of semaglutide-treated participants could represent a meaningful change for children who have not achieved adequate results through lifestyle measures alone.
However, the initial announcement provides topline results, and additional information will be needed to fully assess the magnitude and clinical relevance of the findings. Detailed data from the study are expected at ObesityWeek 2026, including further information on efficacy, safety and other outcomes.
The long-term management of childhood obesity also extends beyond achieving a lower BMI. Sustaining improvements, supporting healthy growth and development, and reducing the risk of future metabolic and cardiovascular complications remain important considerations.
Detailed Data Expected at ObesityWeek 2026
Novo Nordisk plans to present detailed STEP Young results at The Obesity Society’s ObesityWeek 2026 meeting in Washington, D.C., from November 14 through November 17.
The presentation is expected to provide a more comprehensive assessment of once-weekly semaglutide in children aged 6 to under 12 years with obesity, including the full efficacy and safety findings from the Phase 3 program.
For now, the topline results indicate that the STEP Young trial achieved its primary endpoint and that semaglutide, when used alongside reduced-calorie dietary intake and increased physical activity, produced a greater BMI reduction than placebo after 68 weeks. The finding that 40.4% of treated children were no longer classified as having obesity, compared with none in the placebo group, represents a key outcome from the study.
As childhood obesity continues to increase worldwide, the development of evidence-based treatment options for younger children remains an important area of medical research. Novo Nordisk said the STEP Young results support the potential of semaglutide as an additional treatment approach for children living with obesity who require medical intervention alongside lifestyle modification.
About the STEP Young trial
The STEP Young trial is conducted according to regulatory authorities’ post marketing requirements for the semaglutide clinical phase 3 development program thus follows the phase 3 results of semaglutide 2.4 mg in adults and adolescents with obesity.
The phase 3 STEP Young is a randomised, double-blind, placebo-controlled, multinational trial investigating safety and efficacy of semaglutide compared with placebo in 165 children with obesity aged 6 to <12 years, both in combination with reduced-calorie diet and increased physical activity. The children received a maximum dose of either 1.7 mg or 2.4 mg of semaglutide, based on their weight at the start of the trial.