Novo reports 40.4% of children on semaglutide reached a BMI category outside obesity in STEP Young

Novo Nordisk reported early STEP Young results on September 7 in children aged 6 to under 12 with obesity. At 68 weeks, an estimated 40.4% on semaglutide reached a BMI category outside obesity, compared with 0% on placebo. That estimate assumes adherence to treatment. It is not a 40.4% reduction in body weight.

The company announcement concerns 165 children. More than 85% started with severe obesity. Both groups received diet and physical activity support. Novo reported no new safety concerns, including for growth or puberty, but did not provide detailed safety tables. These are manufacturer-reported preliminary results.

The headline percentage measures a change in BMI category

BMI compares weight with height. For children, CDC categories also account for age and sex because growth changes the meaning of a BMI value. Obesity starts at the 95th BMI-for-age percentile. The overweight category extends from the 85th percentile to less than the 95th.

Moving outside the obesity category therefore does not necessarily mean reaching the healthy-weight category. A child can move into the overweight category. A percentile also differs from a percentage change in weight. It describes a position relative to children of the same age and sex in the reference population.

The trial record separates the main outcome from category changes

The ClinicalTrials.gov record identifies percentage change in BMI through week 68 as the main outcome for the younger children. Improvement in weight category is a separate outcome. Novo says the trial met its main goal, but the announcement does not give the numerical BMI reduction. Detailed results are planned for ObesityWeek in November.

The registered study uses random assignment to semaglutide or placebo, with treatment concealed from participants and the study team. This design helps separate a medicine's effect from differences between people who choose different treatments. The registry includes younger children and a separate adolescent group. Its estimated total enrollment of 210 is not the same as the 165-child group described in this announcement.

The record also lists assessments through week 104 and safety-event tracking through week 111. Those planned measures include body composition, blood pressure, and glucose measures. A list of planned outcomes is not a report of results. The registry had no posted results tables when OTN examined it.

The current U.S. label still starts at age 12

The current Wegovy prescribing information includes injection treatment for weight reduction in people aged 12 and older with obesity. It states that safety and effectiveness for this purpose are not established in children younger than 12. Wegovy tablets have no established pediatric safety and effectiveness in that label.

The label also lists risks, including severe digestive reactions, pancreatitis, gallbladder disease, and kidney injury from fluid loss. Its boxed warning concerns thyroid C-cell tumors in rodents, with human relevance unknown. These existing warnings cannot substitute for the missing safety details in younger children.

The announcement does not establish a new approved age group or settle the balance of benefits and risks for an individual child. The complete results will need to show adverse events, treatment discontinuations, and the numerical BMI effect alongside the category result. This report is news about an ongoing research program, not instructions to start, stop, or change a child's treatment.