Obesity Medicines Move Into Elementary School After Novo’s STEP Young Result

On 15 September 2026, STAT’s Readout newsletter led with a question that would have sounded far-fetched a few years ago: obesity drugmakers are now testing medicines in children as young as six. The catalyst is Novo Nordisk‘s 7 September topline from STEP Young, the first large late-stage trial of a GLP-1 obesity drug in elementary-age children. It is the clearest sign yet that the GLP-1 pediatric obesity market now runs well below age 12, where the labels have sat until now.

In STEP Young (NCT05726227), 40.4% of children on once-weekly semaglutide (Wegovy) plus lifestyle intervention moved below the obesity threshold at 68 weeks, against 0% on placebo. The trial randomized 165 children aged 6 to under 12 with obesity, dosed at 1.7 mg or 2.4 mg by starting body weight, and more than 85% began with class II or III disease. Novo describes the study as a post-marketing pediatric commitment carried over from its adult and adolescent 2.4 mg program.

That 40.4% figure comes with a caveat. Novo reported it on the trial-product estimand, the result that assumes every child stayed on treatment. The treatment-policy number, which better reflects real persistence, has not been published. The magnitude of BMI change, body composition, cardiometabolic labs, discontinuations, and the full adverse-event table are also still to come. Novo plans to present the detailed results at ObesityWeek 2026 in Washington, D.C., from 14 to 17 November.

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GLP-1 pediatric obesity: the label and the clinic have split

No GLP-1 or dual GIP/GLP-1 agonist is approved in the United States for common obesity under age 12. Wegovy is labeled from 12, as is liraglutide (Saxenda). Tirzepatide (Zepbound) is adults only. The single exception below age 12 is setmelanotide (Imcivree), approved from age 6 for rare genetic obesities, not for the general population. STEP TEENS previously showed a 16.1% BMI reduction at 68 weeks in adolescents aged 12 to 17.

Prescribing has not waited for the label. A September 2026 Pediatrics analysis of Epic Cosmos data tracked 3.52 million U.S. children aged 8 to 11 with obesity from 2019 through June 2026. Annual GLP-1 prescribing rose from 0.03% to 9.3%, more than 300-fold since 2019. Only about 20,300 children, or 0.6%, received a prescription across the whole period, so the base remains small. Use clustered in severe obesity with comorbidities and skewed toward families with commercial coverage and specialist access.

The 2023 American Academy of Pediatrics guideline lowered the cultural barrier by treating obesity as a chronic disease eligible for medication and allowing consideration from about age 8 in selected patients. Some pediatric obesity specialists still say the evidence does not support prescribing under 12 outside a trial. Others already do, usually for a child with class II or III obesity plus type 2 diabetes, severe sleep apnea, or rapidly worsening metabolic disease.

Lilly and the rest of the field

Eli Lilly has completed a Phase 1 pharmacokinetic study (NCT05696847) in 28 children aged 6 to 11, with results posted in August 2025. Its adolescent SURMOUNT program in ages 12 to 17 is the nearer-term route to a teen label. A planned efficacy trial in children 6 to under 12 (J4M-MC-PW02) sits in Lilly’s European pediatric investigation plan and would put Zepbound on the same age band as STEP Young. Zepbound itself remains adult-only, and a realistic under-12 approval, if the trial runs and reads out positive, is a 2028 or 2029 event rather than 2026.

Novo’s oral semaglutide franchise is also moving younger. PIONEER TEENS met its HbA1c endpoint in ages 10 to 17 with type 2 diabetes, and Novo expects U.S. and EU pediatric filings in the second half of 2026. That is a diabetes label, not an obesity-under-12 program, but it runs in the same direction.

Why companies are going this young

The reasons are structural. About one in five U.S. children and adolescents has obesity, and severe obesity in grade school tracks strongly into adult disease, type 2 diabetes, fatty liver disease, and early cardiometabolic injury. Treating only from age 12 leaves years of pathology unaddressed. Pediatric guidelines increasingly treat obesity as a chronic disease eligible for medication. Regulators require pediatric development for adult obesity products under PREA in the U.S. and pediatric investigation plans in Europe. And off-label use is already happening, so companies face a choice between generating controlled data and leaving the 6 to 11 band to uncontrolled clinic prescribing.

What the 68-week result does not answer

A 68-week trial in 165 children cannot settle questions about linear growth, bone accrual, lean-mass preservation, pubertal timing, or what happens when the drug stops. Novo said safety was consistent with prior pediatric and adult trials, with no new concerns for growth or pubertal development. Payers, pediatric societies, and regulators will press on those points when a supplement is filed, because adult GLP-1 loss includes lean tissue and adult data show weight regain after discontinuation. A child who starts at age 7 may face decades of treatment, or a rebound that is developmentally costly.

The access fight moves down the age ladder

A 6 to 11 label would not translate into automatic coverage. Expect prior authorization tied to BMI percentile plus comorbidity, documented intensive lifestyle intervention, specialist prescribers, and recertification. Some Medicaid programs already restrict teen GLP-1s, and they will be slower still for grade-school children. List prices in the adult market are not a plausible public-program price for a chronic pediatric indication, so Medicaid and CHIP policy will decide uptake more than the FDA label.

The equity problem is already visible in the off-label data. Children with commercial coverage and specialist access get the drugs; others get waitlists. A pediatric label without coverage and clinic capacity would widen that gap.

For manufacturers, pediatric data are now a competitive variable rather than a compliance afterthought. Novo has a first-mover evidence claim in the 6 to 11 band. Lilly cannot cede that band if it wants Zepbound positioned as the broader obesity standard. For investors, STEP Young is incrementally positive for Novo’s franchise narrative and modestly negative for anyone who hoped pediatric use would stay off-limits. It is not a 2026 revenue event.