Semaglutide Childhood Obesity Trial Meets Primary Endpoint as Novo Nordisk's STEP Young Study Shows 40.4% of Children No Longer Classified as Having Obesity

Published: 08/09/2026 Related Information Company: Novo Nordisk Written by Clinical Trials & Data Desk Semaglutide Childhood Obesity Trial data released by Novo Nordisk on September 7, 2026, showed that 40.4% of children treated with once-weekly semaglutide were no longer classified as having obesity after 68 weeks, compared with none of the children who received placebo. The Bagsværd, Denmark-based company announced the first results from its phase 3 STEP Young trial, which evaluated once-weekly subcutaneous semaglutide combined with a reduced-calorie diet and increased physical activity in children aged 6 to under 12 years old living with obesity. The trial arrives as childhood obesity prevalence continues to climb worldwide and as treatment options approved for this age group remain limited when diet and exercise changes alone are not enough. Novo Nordisk said the STEP Young trial was designed specifically to address that gap, testing semaglutide in a population younger than any previously studied in the company's semaglutide obesity program. STEP Young is a randomised, double-blind, placebo-controlled, multinational trial that enrolled 165 children with obesity aged 6 to under 12 years. Every participant, whether assigned to semaglutide or placebo, also received lifestyle modification support throughout the study, including a reduced-calorie diet and increased physical activity. Children received a maximum dose of either 1.7 mg or 2.4 mg of semaglutide, calibrated to their body weight at the start of treatment. At baseline, more than 85% of children enrolled in the trial had class II or class III severe obesity, corresponding to a BMI equal to or above 35 or 40, respectively, in adult terms. Against that backdrop, the Semaglutide Childhood Obesity Trial met its primary endpoint, demonstrating superior BMI reduction at week 68 for children on semaglutide compared with those on placebo. The result means semaglutide helped roughly two out of five children reduce their BMI into a normal-weight or overweight classification, using CDC.gov sex- and age-specific BMI growth charts, compared with none of the children in the placebo arm. Because children are still growing, obesity in this age group is defined as a BMI at or above the 95th percentile for age and sex, with class II and class III obesity defined as 120% and 140% of that 95th percentile, respectively. Ania M. Jastreboff, MD, PhD, professor of medicine and pediatrics at Yale and director of the Yale Obesity Research Center, said childhood obesity carries both immediate and lasting health consequences, pointing to children's 'predilection to adult obesity' as a central concern. She noted that most children in the Semaglutide Childhood Obesity Trial had severe obesity at baseline, yet roughly 40% moved below the obesity threshold within about a year of treatment. Novo Nordisk also pointed to the broader health stakes behind the trial. Children living with obesity face cardiovascular disease risk factors alongside depression, eating disorders, and bullying, with some studies showing their quality of life is comparable to children undergoing cancer treatment. An estimated 177 million children aged 5 to 19 were living with obesity in 2025, a figure projected to rise to 228 million by 2040, according to the company's announcement. The Semaglutide Childhood Obesity Trial was conducted to satisfy regulatory authorities' post-marketing requirements tied to the broader semaglutide phase 3 clinical development program, following earlier phase 3 results of semaglutide 2.4 mg in adults and adolescents with obesity. Endpoint Type Description Population Timepoint Primary endpoint Change in BMI (%) from baseline (week 0) to week 68 Children aged 6 to under 12 years Week 68 Confirmatory secondary endpoint Improvement in BMI classification from baseline to week 68 Children aged 6 to under 12 years Week 68 Supportive secondary endpoints Changes in anthropometric measures, cardiovascular risk factors, glucose metabolism, and body composition (DXA subgroup) Children aged 6 to under 12 years Week 68 / Week 104 Martin Holst Lange, executive vice president, chief scientific officer and head of research and development at Novo Nordisk, said health challenges tied to childhood obesity can begin early and affect wellbeing for life. He said the company, as a long-standing developer of paediatric obesity medicine, was encouraged by the STEP Young results and semaglutide's potential to help children manage obesity alongside lifestyle changes, potentially preventing serious health risks later in life. Novo Nordisk reported that the overall safety and tolerability of semaglutide observed in the Semaglutide Childhood Obesity Trial were consistent with previous company trials of semaglutide and liraglutide in paediatric and adult populations, and that no new safety concerns were identified. The company specifically noted that no safety concerns emerged for growth or pubertal development, a key consideration for regulators evaluating any obesity treatment intended for young children. Detailed results from the Semaglutide Childhood Obesity Trial will be presented at The Obesity Society's annual ObesityWeek 2026 meeting, scheduled for November 14 to 17, 2026, in Washington, D.C. Novo Nordisk did not disclose a projected regulatory filing timeline, specific trial registry identifiers, or pricing information for a potential paediatric obesity indication in its announcement, and those details remain not disclosed pending further updates from the company. Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist that mimics the naturally occurring hormone GLP-1, which regulates blood sugar and body weight. It has been studied across multiple cardiometabolic disease programs, including type 2 diabetes, obesity, cardiovascular disease, heart failure, chronic kidney disease, and liver disease. Brand Name Formulation Disclosed Use Context Wegovy Injection or tablet Weight management Ozempic Injection or tablet Type 2 diabetes Rybelsus Tablet Type 2 diabetes Novo Nordisk, founded in 1923 and headquartered in Denmark, employs about 66,700 people across 80 countries and markets its products in around 170 countries. The company describes its purpose as driving change to defeat serious chronic diseases, building on its heritage in diabetes care. Read More