Semaglutide Moves 40% of Obese Children Below Obesity BMI in Novo Nordisk Trial

On Monday, Novo Nordisk reported findings from its STEP Young Phase 3 study: among children 6 to under 12 years old with obesity, 40.4% who were treated with a weekly semaglutide injection saw their BMI drop below the obesity threshold at 68 weeks.

Enrolling 165 children with obesity, the study assigned them to semaglutide or placebo, along with lifestyle interventions such as a calorie-restricted diet and more exercise. In the placebo arm, no child attained a BMI under the obesity threshold over the same period.

The study achieved its primary endpoint, demonstrating superior BMI reduction with semaglutide versus placebo. At baseline, upwards of 85% of participants met the criteria for class II or class III severe obesity, which in adults corresponds to a BMI of 35 or greater and 40 or greater, respectively.

Dosing in the trial reached a maximum of 1.7 mg or 2.4 mg of semaglutide, determined by each child's baseline weight, and was delivered as a subcutaneous injection once a week.

Ania M. Jastreboff, Professor of Medicine and Pediatrics at Yale and Director of the Yale Obesity Research Center, said: "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."

STEP Young's safety and tolerability profile paralleled those seen in earlier semaglutide and liraglutide trials involving pediatric and adult participants. No novel safety alerts emerged, and no adverse effects on growth or pubertal development were reported.

It is estimated that 177 million children between ages 5 and 19 were obese in 2025; projections place that total at 228 million by 2040.

Novo Nordisk plans to present the full trial analysis at The Obesity Society's annual meeting, ObesityWeek 2026, to be held from November 14 to 17 in Washington, D.C.

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