The STEP Trials: Semaglutide's Weight Management Evidence
TRIAL-000001
Part of the DietApp.com GLP-1 Trial Database, a comprehensive, regularly reviewed resource.
What It Is
STEP, Semaglutide Treatment Effect in People with Obesity, is the clinical trial program that established semaglutide's effectiveness for chronic weight management. STEP 1, published in the New England Journal of Medicine in 2021, is the landmark trial in the series and formed the primary basis for Wegovy's FDA approval.
Key Results
STEP 1 showed an average weight loss of 14.9% of body weight at 68 weeks in adults with overweight or obesity, without diabetes, taking semaglutide 2.4 mg weekly alongside lifestyle intervention. Subsequent trials in the series, including STEP 3, examined semaglutide combined with more structured behavioral support, which showed even greater average weight reduction than semaglutide alone.
Side Effects Observed
The dominant side effects across the STEP trials were gastrointestinal, primarily nausea, constipation, and fatigue, occurring mainly during dose escalation. Serious adverse events were uncommon, and the trials did not identify an increased risk of pancreatitis or thyroid tumors in humans, though the boxed warning based on rodent studies remains part of semaglutide's label as a precaution.
What Happens After Stopping
STEP 1 extension data found that participants who stopped semaglutide regained roughly two-thirds of their lost weight within a year, evidence that's directly informed the general understanding that GLP-1 medications function more like a long-term treatment, similar to blood pressure medication, than a short-course fix.
References
- Wilding JPH et al., STEP 1 Trial, NEJM 2021
Related Resources
Related Articles
How STEP Compares to Tirzepatide's SURMOUNT Program
| Trial | Population | Real Weight Loss Result |
|---|---|---|
| STEP 1 | Obesity, no diabetes | 14.9% at 68 weeks |
| STEP 3 | Semaglutide + structured behavioral support | Greater than semaglutide alone |
| SURMOUNT-1 (tirzepatide, for comparison) | Obesity, no diabetes | Up to 20.9% |
See DietApp's SURMOUNT Trials page for tirzepatide's own weight-management evidence, and SELECT trial page for semaglutide's separate cardiovascular risk reduction approval.
Frequently Asked Questions
Why did STEP 3 show better results than STEP 1? Structured behavioral support alongside the medication produced real, additive benefit beyond the medication alone.
Does regaining weight after stopping mean the medication failed? No, real, expected physiology, appetite-regulating hormones return toward baseline once the medication is discontinued, similar to how blood pressure rises again after stopping blood pressure medication.
Is the boxed warning about thyroid tumors still relevant if human trials didn't find it? Yes, it remains a real, precautionary label requirement based on rodent studies, even though STEP trials themselves didn't identify this risk in humans.
Explore More
Explore the full GLP-1 Tracker knowledge base on DietApp.com
Get Started
Download DietApp.com to track your own progress alongside the evidence behind your treatment.
About DietApp.com
DietApp.com combines evidence-based GLP-1 medication education with practical treatment tracking tools. The information on DietApp.com is intended for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.
Last medically reviewed and updated: July 11, 2026.
step-trials-semaglutide