Novo Nordisk says semaglutide moved 40.4% of children aged 6 to 11 below the obesity threshold

Novo Nordisk reported on Sept. 7, 2026 that 40.4% of children aged 6 to under 12 treated with once-weekly semaglutide in the phase 3 STEP Young trial were no longer classified as having obesity after 68 weeks, compared with none of the children who received a placebo ^[1][2]. Every child in the trial also received a reduced-calorie diet and increased physical activity ^[1][2].

STEP Young enrolled 165 children with obesity and was randomized, double-blind, placebo-controlled and multinational ^[1][3]. Children received a maximum weekly dose of either 1.7 mg or 2.4 mg of semaglutide, based on their weight at the start of the trial ^[1][3]. More than 85% of them had class II or III obesity at baseline, the more severe categories ^[1][3]. In children, obesity is defined as a BMI at or above the 95th percentile for age and sex on CDC growth charts; class II and III begin at 120% and 140% of that percentile ^[1].

Novo said the trial met its primary endpoint, showing a greater BMI reduction at week 68 with semaglutide than with placebo ^[1][2]. The topline announcement did not include average BMI changes, the between-group difference, confidence intervals or a statistical analysis, and it did not disclose adverse-event rates, discontinuations, serious adverse events or gastrointestinal side-effect rates ^[3].

The 40.4% figure uses what the company calls the trial product estimand, which estimates the treatment effect if all children adhered to treatment ^[1][2][3]. In its announcement, Novo described the result as semaglutide helping "two out of five of the children reduce their BMI to a normal weight or overweight classification compared with none of the children in the placebo group" ^[1].

Ania M. Jastreboff, a professor of medicine and pediatrics at Yale and director of the Yale Obesity Research Center, said most children in the trial had severe obesity at baseline, yet treatment moved about 40% of them below the obesity threshold "within about a year of treatment" ^[1][3]. Martin Holst Lange, Novo's chief scientific officer, said the company was "encouraged by the positive STEP Young results" ^[1][2].

Novo said the overall safety and tolerability of semaglutide were consistent with earlier trials in adults and adolescents, with no new safety concerns, and that no safety concerns were identified for growth or pubertal development ^[1][2][3].

Semaglutide is sold as Wegovy, Ozempic and Rybelsus ^[1]. It is not approved for children under 12, and no new regulatory authorization for that age group was reported alongside the results ^[2][3]. Prescriptions of GLP-1 weight-loss drugs to U.S. children under 12 rose more than 300-fold since 2019, according to a study published Sept. 4, 2026 ^[2].

Why it matters for patients

Childhood obesity often continues into adulthood, where related complications can appear earlier and more severely ^[1]. Novo cited research estimating that 177 million children aged 5 to 19 were living with obesity in 2025, a figure projected to reach 228 million by 2040 ^[1]. For families in this age range, approved drug options have been limited: semaglutide has been tested and approved for adults and adolescents, but not for children younger than 12 ^[1][2][3].

The result is a topline figure from one trial of 165 children, not a full dataset. Because it assumes full adherence, it does not describe what happens when children miss doses or stop treatment ^[1][2][3]. Three things have not been reported: the size of the average BMI difference between the two groups, the rates of side effects and dropouts, and whether any benefit persists after treatment ends ^[3]. Effects on growth, puberty and metabolic health beyond the 68-week treatment period have also not been disclosed ^[3].

What happens next

Novo said detailed STEP Young results will be presented at ObesityWeek 2026, Nov. 14-17 in Washington, D.C. ^[1][3]. The trial's follow-up extends to week 104 ^[3]. Whether Novo will seek regulatory approval for semaglutide in children under 12 has not been disclosed ^[3].