Semaglutide for Childhood Obesity

What did the STEP Young semaglutide trial find?

STEP Young compared weekly semaglutide with placebo, with dietary and activity support in both groups. Novo Nordisk announced the results on September 7.

At week 68, an estimated 40.4% receiving semaglutide fell below the obesity threshold, versus 0% receiving placebo. That analysis assumed everyone adhered to treatment; it does not describe expected outcomes for everyone starting therapy. Detailed findings are scheduled for presentation in November. [Novo Nordisk announcement](https://rss.globenewswire.com/news-release/2026/09/07/3357042/0/en/novo-nordisk-step-young-phase-3-data-40-4-of-children-living-with-obesity-achieved-a-bmi-below-the-obesity-threshold-with-semaglutide-and-lifestyle-modification.html)

What does a lower BMI mean for a growing child?

Children's BMI categories differ from adult categories because body proportions change during development. CDC growth charts compare BMI with reference values for children of the same age and sex. Obesity begins at the 95th percentile, while the overweight category extends from the 85th percentile to below the 95th. Moving below the obesity threshold therefore does not necessarily mean reaching the healthy-weight category. [CDC child and teen BMI categories](https://www.cdc.gov/bmi/child-teen-calculator/bmi-categories.html)

A percentage of participants crossing a BMI threshold also must not be confused with their percentage weight loss. BMI incorporates height, so a growing child's BMI can decline without a comparable decrease in kilograms. CDC emphasizes that BMI percentile is not a complete diagnostic assessment. Growth history, other screening findings, genetics, eating patterns, sleep and access to healthy food help clinicians understand whether a change represents better health. [CDC guidance on childhood obesity screening](https://www.cdc.gov/obesity/child-obesity-screening/index.html)

Could these findings change obesity treatment for children under 12?

Semaglutide activates GLP-1 receptors, helping regulate appetite and increasing feelings of fullness. This biological effect explains why the medicine can complement nutritional and behavioral support. However, the current U.S. Wegovy injection label establishes obesity treatment use from age 12; safety and effectiveness for weight management below that age remain unestablished in the labeling. An encouraging trial result is one part of the evidence regulators assess when considering a younger population. [EMA explanation of semaglutide](https://www.ema.europa.eu/en/medicines/human/EPAR/wegovy), [U.S. Wegovy prescribing information](https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b)

Known adverse effects in approved populations include nausea, vomiting, diarrhea and constipation. The prescribing information also warns about pancreatitis, gallbladder disease and dehydration-related kidney problems. These established risks make detailed pediatric safety findings essential. A clinically useful assessment should examine treatment discontinuation, nutritional adequacy, growth and pubertal development alongside BMI changes. Whether benefits persist after treatment ends, and whether early treatment prevents later complications, are separate questions that cannot be answered by a BMI endpoint alone. [U.S. Wegovy safety information](https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b)