A newly announced clinical trial may mark an important step toward expanding medical treatment for childhood obesity. On September 7, 2026, Novo Nordisk reported topline results from STEP Young, a phase 3 trial of once-weekly semaglutide in children ages 6 to younger than 12 with obesity.
After 68 weeks, 40.4% of children assigned to semaglutide were below the obesity threshold, compared with none of those assigned to placebo. Both groups also received support for a reduced-calorie diet and increased physical activity.
The result is notable because medication options for younger children remain limited. It also arrives amid a broader change in how clinicians approach pediatric obesity: as a complex chronic disease that may require more than advice about diet and exercise alone.
Still, the announcement is an early look at the study. Families and clinicians will need the complete data before they can fully judge the treatment’s benefits and risks.
What the STEP Young trial found
STEP Young enrolled 165 children in a randomized, double-blind, placebo-controlled multinational trial. More than 85% had class II or class III severe obesity at enrollment. Children received either semaglutide at a maximum weekly dose of 1.7 or 2.4 milligrams, based on starting weight, or a placebo. The primary endpoint was the percentage change in BMI from baseline through week 68.
Novo Nordisk said the study met that primary endpoint, meaning BMI declined more with semaglutide than with placebo. The company highlighted a secondary result that may be easier for families to understand: Roughly two in five children receiving semaglutide moved from the obesity range into the overweight or normal-weight range on age- and sex-specific growth charts.
Ania M. Jastreboff, M.D., Ph.D., Yale Obesity Research Center, said:
Treatment with semaglutide resulted in a BMI percentile category below the obesity threshold in approximately 40% of the children.
For children, BMI is interpreted differently than it is for adults. Clinicians use percentiles that account for age and sex because children are still growing. Crossing below the obesity threshold therefore reflects a change in BMI category, not a single adult-style BMI cutoff.
Why these findings matter
Childhood obesity can affect health well before adulthood. It is associated with cardiometabolic risk factors as well as depression, disordered eating, bullying, and reduced quality of life. Severe obesity is also likely to persist into adulthood, increasing the likelihood that related complications will appear earlier.
Let’s note that Wegovy, the semaglutide product used for chronic weight management, is already used in older populations, but current reporting notes that GLP-1 weight-loss drugs are not approved for children younger than 12. STEP Young could therefore support a future regulatory review for a group with fewer evidence-based medication choices.
Medication would not replace comprehensive care
The trial did not test semaglutide by itself. Every participant received lifestyle support, including dietary changes and increased physical activity. That detail matters: Pediatric obesity treatment is typically family-centered and may involve nutrition, physical activity, sleep, behavioral health, and management of related medical conditions. If semaglutide is eventually authorized for younger children, it would be considered one possible component of individualized care rather than a standalone solution.
Important questions remain
The 40.4% figure is promising, but the initial announcement did not disclose several details needed for a complete benefit-risk assessment. Contemporary Pediatrics noted that the topline release did not provide the mean BMI change, the difference between groups, confidence intervals, or a full statistical analysis. It also did not report detailed rates of gastrointestinal side effects, serious adverse events, or treatment discontinuation.
Novo Nordisk reported that overall safety and tolerability were consistent with prior semaglutide and liraglutide studies and that no new concerns involving growth or pubertal development were identified. Even so, longer follow-up is essential in children. Researchers and clinicians will want to understand effects on growth, puberty, body composition, metabolic health, emotional well-being, and what happens if treatment stops.
STEP Young offers encouraging evidence that semaglutide, combined with lifestyle treatment, may help some children with severe obesity achieve a clinically meaningful change in BMI category. It does not yet establish that the medication should be broadly used in children under 12.
Full results are expected to be presented at ObesityWeek in November 2026, when independent experts will be able to examine the magnitude of BMI reduction, adverse events, discontinuations, and other outcomes in greater detail. In the meantime, parents should not use medication prescribed to another person or seek a GLP-1 product without age-appropriate medical evaluation and monitoring.
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Source: “Novo Nordisk STEP Young phase 3 data: 40.4% of children living with obesity achieved a BMI below the obesity threshold with semaglutide and lifestyle modification,” GlobeNewswire, 9/7/26
Source: “Semaglutide improves BMI category in children aged 6 to 11 years in phase 3 trial,” Contemporary Pediatrics, 9/8/26
Source: “GLP1 Drugs Work for Kids, Says Novo Nordisk. They Could Be Another Huge Market.,” Barrons.com, 9/8/26
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