Novo Nordisk’s once-weekly semaglutide helped two in five children with obesity shed the condition within about a year, according to first results from a phase 3 trial.

 

The STEP Young trial, which evaluated semaglutide alongside a reduced-calorie diet and increased physical activity, found a significantly greater reduction in body mass index (BMI) at week 68 among children receiving semaglutide than those given placebo.

 

Notably, 40.4% of children treated with semaglutide were no longer classified as having obesity at week 68, compared with none in the placebo group. Both groups received lifestyle interventions throughout the study.

 

The findings are particularly significant because the trial population had a high burden of severe obesity. More than 85% of participants had class II or class III severe obesity at baseline.

 

"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, 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 40% of the children within about a year of treatment."

 

The results come as childhood obesity continues to expand as a global health concern, while treatment options for younger children remain limited when lifestyle changes alone do not produce sufficient results.

 

An estimated 177 million children aged 5 to 19 were living with obesity in 2025, with that number projected to reach 228 million by 2040.

 

"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.”

 

Novo Nordisk said the overall safety and tolerability profile of semaglutide in STEP Young was consistent with findings from previous paediatric and adult trials involving semaglutide and liraglutide.

 

The company reported no new safety concerns, including no identified concerns related to growth or pubertal development.