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
Phase 3 STEP Young topline results support semaglutide’s efficacy and paediatric safety profile in children 6–11 years with obesity.
Rhea-AI Summary
Novo Nordisk (NVO) reported phase 3 STEP Young topline data showing once-weekly semaglutide plus lifestyle modification reduced BMI more than placebo in children aged 6 to under 12 years with obesity at week 68.
The primary endpoint of percentage change in BMI from baseline to week 68 was met, demonstrating superior BMI reduction versus placebo. A key secondary outcome showed that 40.4% of children receiving semaglutide were no longer classified as having obesity, compared with 0% on placebo, when both groups also followed a reduced-calorie diet and increased physical activity. At baseline, more than 85% of participants had class II or III severe obesity. The trial enrolled 165 children and used weight-based doses up to 1.7 mg or 2.4 mg. Overall safety and tolerability, including effects on growth and pubertal development, were reported as consistent with prior paediatric and adult semaglutide trials, with no new safety concerns identified.
Positive
- Primary endpoint met: superior BMI reduction with semaglutide vs placebo at week 68
- 40.4% of semaglutide-treated children were below the obesity BMI threshold vs 0% on placebo at week 68
- Trial enrolled 165 children aged 6 to under 12 years with obesity, over 85% with class II or III severe obesity at baseline
- Maximum semaglutide dose of 1.7 mg or 2.4 mg weekly used alongside lifestyle modification
- Safety and tolerability profile, including growth and pubertal development, was consistent with prior semaglutide trials with no new safety concerns reported
Negative
- None.
News Explained
The release is an initial topline readout: Novo Nordisk says detailed STEP Young results will be presented at ObesityWeek 2026 in Washington, DC, on
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Data highlights
- The STEP Young phase 3 trial met its primary endpoint, demonstrating greater body mass index (BMI) reduction in children aged 6 to under 12 treated with once-weekly subcutaneous semaglutide compared with placebo
- Both groups received lifestyle modification throughout the trial, including reduced-calorie diet and increased physical activity
40.4% * of the children treated with semaglutide were no longer classified as having obesity** after 68 weeks compared with non (0% ) treated with placebo- The overall safety and tolerability of semaglutide were consistent with those seen in adults and adolescents trials with semaglutide
Bagsværd, Denmark, 7 September 2026 – Novo Nordisk today announced first results from the STEP Young phase 3 trial, evaluating once-weekly semaglutide in combination with a reduced-calorie diet and increased physical activity in children aged 6 to under 12 years old with obesity. Obesity prevalence is growing in this age group, for whom there are limited clinically tested and approved treatments available when lifestyle modifications are not sufficient.
At baseline, more than
“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,” said Ania M. Jastreboff, MD, PhD, Professor of Medicine (Endocrinology) and Pediatrics (Pediatric Endocrinology) at the Yale and Director of the Yale Obesity Research Center (Y-Weight). “Most of the children in the STEP Young trial were classified as having severe (class II or III) obesity at baseline, yet treatment with semaglutide resulted in a BMI percentile category below the obesity threshold in approximately
Children living with obesity experience cardiovascular disease risk factors, alongside depression, eating disorders, and bullying, with studies showing that their quality of life is comparable to children undergoing cancer treatment.1-3 Without effective intervention, childhood obesity strongly tracks into adulthood1, where obesity-related complications emerge earlier and more severely,1-3 substantially shortening life expectancy.4 An estimated 177 million children aged 5 to 19 were living with obesity in 2025, and this figure is projected to rise to 228 million by 2040.5
"For children living with obesity and their families, health challenges can begin early and affect wellbeing throughout life,” said Martin Holst Lange, executive vice president, chief scientific officer and head of Research & Development at Novo Nordisk. “As a pioneer in paediatric obesity medicine, we are encouraged by the positive STEP Young results and semaglutide’s potential to help children living with obesity who need medical treatment, alongside lifestyle changes, to better manage their obesity. This may prevent serious health risks later in life.”
The overall safety and tolerability of semaglutide observed in STEP Young were consistent with previous Novo Nordisk paediatric and adult trials with semaglutide and liraglutide, and no new safety concerns were identified. Furthermore, no safety concerns were identified for growth or pubertal development.
Detailed STEP Young results will be presented at The Obesity Society’s annual meeting ObesityWeek 2026, 14-17 November in Washington DC, United States.
* Based on the trial product estimand: treatment effect if all children adhered to treatment
**Based on CDC.gov sex- and age-specific BMI growth charts. Using percentiles to define BMI categories in children is important because they are still growing. In children, obesity is defined as a BMI at or above the 95th percentile for age and sex. Obesity classes II and III in children are defined as a BMI ≥
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.
| Endpoint | 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 |
**Based on CDC.gov sex- and age-specific BMI growth charts. Using percentiles to define BMI categories in children is important because they are still growing. In children, obesity is defined as a BMI at or above the 95th percentile for age and sex. Obesity classes II and III in children are defined as a BMI ≥
About semaglutide
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist that mimics the effects of the naturally occurring hormone GLP-1, which regulates blood sugar and body weight. Semaglutide has been tested in several robust clinical development programmes and outcome studies in cardiometabolic diseases, including type 2 diabetes, obesity, cardiovascular disease, heart failure, chronic kidney disease, liver disease, and other related cardiometabolic diseases. Semaglutide is marketed under the brand names Wegovy® (injection or tablet), Ozempic® (injection or tablet), and Rybelsus® (tablet).
About Novo Nordisk
Novo Nordisk is a leading global healthcare company founded in 1923 and headquartered in Denmark. Our purpose is to drive change to defeat serious chronic diseases built upon our heritage in diabetes. We do so by pioneering scientific breakthroughs, expanding access to our medicines, and working to prevent and ultimately cure disease. Novo Nordisk employs about 66,700 people in 80 countries and markets its products in around 170 countries. For more information, visit novonordisk.com, Facebook, Instagram, X, LinkedIn and YouTube.
Contacts for further information
| Novo Nordisk Media: | |
| Ambre James-Brown +45 3079 9289 globalmedia@novonordisk.com | Liz Skrbkova (US) +1 609 917 0632 USMediaRelations@novonordisk.com |
| Novo Nordisk Investors: | |
| Michael Novod +45 3075 6050 nvno@novonordisk.com | Sina Meyer +45 3079 6656 azey@novonordisk.com |
| Ida Schaap Melvold +45 3077 5649 idmg@novonordisk.com | Christoffer Togo Solgaard-Tullin +45 3079 1471 cftu@novonordisk.com |
| Mads Berner Bruun +45 3075 2936 mbbz@novonordisk.com | |
| Alex Bruce (US) +1 640 230 0276 axeu@novonordisk.com | Frederik Taylor Pitter (US) +1 609 613 0568 fptr@novonordisk.com |
References
- Hampl SE, Hassink SG, Skinner AC, et al. Clinical Practice Guideline for the Evaluation and Treatment of Children and Adolescents With Obesity. Pediatrics 2023; 151
- Kumar S, Kelly AS. Review of Childhood Obesity: From Epidemiology, Etiology, and Comorbidities to Clinical Assessment and Treatment. Mayo Clin Proc 2017; 92: 251-65.
- Schwimmer JB, Burwinkle TM, Varni JW. Health-related quality of life of severely obese children and adolescents. Jama 2003; 289: 1813-9.
- Wiedemann UCH, van den Akker ELT, Barber TM, et al. Early-Onset of Obesity Model: Impact of Early-Onset Obesity on Comorbidity Risk and Life Expectancy. Obes Facts 2026; 19: 265-79.
- World Obesity Federation. World Obesity Atlas 2026. Available at: https://s3-eu-west-1.amazonaws.com/wof-files/WOF_Obesity_Atlas_2026.pdf (accessed August 2026)
Attachment
FAQ
What age group and population did the STEP Young trial study?
The STEP Young trial investigated once-weekly subcutaneous semaglutide in children aged 6 to under 12 years living with obesity. At baseline, more than 85% of participants had class II or III severe obesity, meaning BMI levels corresponding to at least 35 or 40 in adults, respectively, when adjusted for age and sex using CDC BMI growth charts.
What was the design of the STEP Young phase 3 trial?
STEP Young was a randomised, double-blind, placebo-controlled, multinational phase 3 trial. It compared semaglutide with placebo in 165 children with obesity, with all participants receiving lifestyle modification including a reduced-calorie diet and increased physical activity throughout the trial.
What endpoints were assessed in STEP Young?
The primary endpoint was percentage change in BMI from baseline (week 0) to week 68. A confirmatory secondary endpoint was improvement in BMI classification from baseline to week 68. Supportive secondary endpoints included changes in anthropometric measures, cardiovascular risk factors, glucose metabolism, and body composition in a DXA subgroup, assessed up to week 68 and week 104.
What dosing regimen of semaglutide was used for children in the trial?
Children in STEP Young received once-weekly subcutaneous semaglutide at a maximum dose of 1.7 mg or 2.4 mg, depending on their weight at the start of the trial. All children were treated in combination with lifestyle modification measures.
How was obesity defined for children in STEP Young?
Obesity and its classes were defined using CDC sex- and age-specific BMI growth charts. Childhood obesity was defined as BMI at or above the 95th percentile for age and sex. Obesity class II and III were defined as BMI at least 120% and 140% of the 95th percentile, respectively.
When and where will full STEP Young data be presented?
Detailed STEP Young results are planned to be presented at The Obesity Society’s ObesityWeek 2026, which will take place from 14–17 November 2026 in Washington DC, United States.
In what broader clinical context has semaglutide been studied?
Semaglutide is a GLP-1 receptor agonist that has been investigated in multiple clinical development programmes and outcome studies across cardiometabolic diseases, including type 2 diabetes, obesity, cardiovascular disease, heart failure, chronic kidney disease, liver disease, and other related conditions. It is marketed under the brand names Wegovy, Ozempic, and Rybelsus.