Semaglutide Results: What the Trials Report by Timepoint

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Short answer: Semaglutide before and after results on this page come from published trials rather than photos, the same approach as our tirzepatide results by timepoint. The STEP trials report average weight change for branded semaglutide 2.4 mg (Wegovy) at set timepoints, not month by month. In STEP 1, the average change at 68 weeks (about 16 months) was -14.9% on semaglutide compared with -2.4% on placebo (Wilding et al., NEJM 2021). Compounded semaglutide was not studied in these trials.

This page reports what the published trials measured. It is not a prediction of what any one person will lose, and it is not medical advice. Your provider sets the dose.

Why does this page have no before-and-after photos?

Most “semaglutide before and after” results online are photos or personal stories. You can’t check those: you don’t know the dose, the product, the diet or how long it took. So this page shows no photos and no testimonials. It reports only the average results that the trial publications give, at the timepoints those publications give.

What did the trials report, timepoint by timepoint?

Each trial measured weight at its own main timepoints. The table pulls the headline averages from six publications. Months are approximate (weeks divided by 4.33).

Timepoint	Trial and who was studied	Reported average weight change
Week 20 (about 5 months)	STEP 4 run-in, adults with obesity or overweight without diabetes, after reaching 2.4 mg	-10.6% among the 803 people who completed the run-in and were randomized
Week 68 (about 16 months)	STEP 1, 1,961 adults with obesity or overweight without diabetes, plus lifestyle intervention	-14.9% (semaglutide) vs -2.4% (placebo)
Week 68 with intensive behavioral therapy	STEP 3, 611 adults, low-calorie diet for 8 weeks and 30 counseling visits	-16.0% (semaglutide) vs -5.7% (placebo)
Week 104 (about 2 years)	STEP 5, 304 adults with obesity or overweight without diabetes	-15.2% (semaglutide) vs -2.6% (placebo)
Week 120 (about 2.3 years)	STEP 1 extension, 327 people, one year after stopping treatment at week 68	-5.6% (former semaglutide group) vs -0.1% (former placebo group)
Week 208 (about 4 years)	SELECT, 17,604 adults with existing cardiovascular disease and overweight or obesity, without diabetes	-10.2% (semaglutide) vs -1.5% (placebo)

Sources: STEP 4, STEP 1, STEP 3, STEP 5, STEP 1 extension, SELECT. All studied branded semaglutide, not a compounded product.

Weeks 1 to 16: what does the Wegovy dose escalation look like?

The Wegovy prescribing information starts at 0.25 mg and steps up every 4 weeks, and says to follow this schedule to reduce the risk of gastrointestinal adverse reactions (DailyMed, Wegovy):

Weeks	Once-weekly injection dose in the Wegovy prescribing information
1 to 4	0.25 mg
5 to 8	0.5 mg
9 to 12	1 mg
13 to 16	1.7 mg
17 onward	Maintenance dose: 1.7 mg or 2.4 mg (recommended) for adult weight reduction

The Wegovy prescribing information, revised in June 2026, also allows an increase to a maximum of 7.2 mg once weekly for adults who have tolerated 2.4 mg for at least 4 weeks. The STEP trials on this page studied 2.4 mg. The trials’ headline results do not include an average weight change at weeks 4, 8, 12 or 16. Your provider sets the dose; our GLP-1 dosing help page covers common questions.

Week 20: what did STEP 4 report after about 5 months?

In STEP 4, 902 adults took semaglutide for a 20-week run-in: 16 weeks of dose escalation and 4 weeks at 2.4 mg. The 803 who reached 2.4 mg and went on to the main trial had an average weight loss of 10.6% during the run-in (Rubino et al., JAMA 2021). This group excludes people who did not reach the full dose, so it is not directly comparable with the full STEP 1 population.

Week 68: what did STEP 1 and STEP 3 report after about 16 months?

STEP 1 enrolled 1,961 adults with obesity or overweight and no diabetes. Participants were assigned 2 to 1 to semaglutide or placebo, both with lifestyle intervention, for 68 weeks (Wilding et al., NEJM 2021). The authors reported these results at week 68:

Group	Average weight change	Lost 5% or more	Lost 10% or more	Lost 15% or more
Semaglutide 2.4 mg	-14.9% (-15.3 kg)	86.4%	69.1%	50.5%
Placebo	-2.4% (-2.6 kg)	31.5%	12.0%	4.9%

The same paper reports that nausea and diarrhea were the most common adverse events, typically transient and mild to moderate, and that 4.5% of the semaglutide group stopped treatment because of gastrointestinal events, compared with 0.8% on placebo.

STEP 3 added an 8-week low-calorie diet and 30 intensive behavioral therapy visits for everyone. At week 68 it reported -16.0% with semaglutide vs -5.7% with placebo, and 86.6% vs 47.6% lost at least 5% (Wadden et al., JAMA 2021).

Week 104 and week 208: what do the longer trials report?

STEP 5 ran for 104 weeks. It reported an average change of -15.2% with semaglutide vs -2.6% with placebo, and 77.1% vs 34.4% lost at least 5% (Garvey et al., Nat Med 2022).

SELECT was a cardiovascular outcomes trial in adults who already had cardiovascular disease. Its weight analysis reported an average change at 208 weeks of -10.2% with semaglutide vs -1.5% with placebo (Ryan et al., Nat Med 2024). Because the population and goals differ from the STEP trials, its numbers are not directly comparable.

How long does it take for semaglutide to work?

The trials answer this only at the timepoints they published. The earliest average on this page is week 20, when STEP 4 reported -10.6% among people who had reached the 2.4 mg dose (Rubino et al., 2021). The headline results of the trials cited here do not include weekly or monthly averages before week 20.

How much weight can you lose on semaglutide?

The published averages range from -14.9% to -16.0% at 68 weeks and -15.2% at 104 weeks in the STEP trials above. These are group averages. In STEP 1, 86.4% of the semaglutide group lost at least 5%, so not everyone did, and about half (50.5%) lost 15% or more (Wilding et al., 2021). Whether semaglutide is appropriate for you is a question for a licensed provider.

For the two drugs side by side, see the tirzepatide vs semaglutide trial comparison.

When should you call a doctor?

The Wegovy Medication Guide tells patients to contact their healthcare provider, or get medical help, if they notice any of these (DailyMed, Wegovy):

• Severe stomach pain that will not go away, with or without nausea or vomiting, sometimes felt in the back (possible pancreatitis)
• Pain in the upper stomach, yellowing of the skin or eyes, fever or clay-colored stools (possible gallbladder problems)
• Nausea, vomiting or diarrhea that does not go away, which can cause dehydration and kidney problems
• Swelling of the face, lips, tongue or throat, severe rash or itching, very rapid heartbeat, problems breathing or swallowing, or fainting (serious allergic reaction)
• Dizziness, sweating, shakiness, confusion or a fast heartbeat if you have type 2 diabetes and also take insulin or a sulfonylurea (low blood sugar)
• A heart that feels like it is racing or pounding for several minutes while at rest
• A lump or swelling in the neck, hoarseness, trouble swallowing or shortness of breath

The Wegovy prescribing information carries a boxed warning: it reports Wegovy caused thyroid C-cell tumors in rodents, and it is contraindicated in anyone with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2) (DailyMed, Wegovy). Our semaglutide safety information page covers the rest of the Wegovy prescribing information.

What did the trials report when people stopped semaglutide?

STEP 4 was designed to test this. After the 20-week run-in, people were randomly assigned to keep taking semaglutide or switch to placebo for 48 more weeks. From week 20 to week 68, the average weight change was -7.9% for those who continued and +6.9% for those switched to placebo (Rubino et al., 2021).

The STEP 1 extension followed 327 participants for a year after all treatment, including the lifestyle program, stopped at week 68. The semaglutide group had lost 17.3% by week 68, then regained 11.6 percentage points by week 120, a net loss of 5.6%. The authors wrote that participants regained two-thirds of their prior weight loss (Wilding et al., Diabetes Obes Metab 2022).

Do these results apply to compounded semaglutide?

No. No trial in this table studied a compounded product. The STEP trials studied branded semaglutide made by Novo Nordisk and sold as Wegovy (Wegovy prescribing information). For how the two compounded GLP-1s compare, see compounded semaglutide vs tirzepatide.

What about semaglutide reviews?

PrescribedRX doesn’t publish patient reviews or testimonials about semaglutide. This page reports the trial averages and ranges, with their placebo groups, instead. For the side effects listed in the Wegovy prescribing information, see our semaglutide side effects guide.

How does semaglutide work with PrescribedRX?

You start with a short online eligibility check. A licensed provider reviews your answers and decides whether it is appropriate for you. If a prescription is issued, a licensed partner pharmacy fills compounded semaglutide. Compounded medications are prepared by licensed pharmacies and are not FDA-approved. It is self-pay with no insurance, and availability varies by state. Your provider sets the dose.

• Compounded semaglutide: 3 month plan $420 · $140/mo · Billed every 3 months. Cancel anytime.

See the compounded semaglutide plan for what each shipment includes, our guide to GLP-1 prices without insurance, or browse all weight loss treatments.

Related reading: semaglutide cost: brand and compounded prices

Sources

1. Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384:989-1002. PubMed. Accessed Oct 2026.
2. Rubino D, Abrahamsson N, Davies M, et al. Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance in Adults With Overweight or Obesity: The STEP 4 Randomized Clinical Trial. JAMA. 2021;325:1414-1425. PubMed. Accessed Oct 2026.
3. Wadden TA, Bailey TS, Billings LK, et al. Effect of Subcutaneous Semaglutide vs Placebo as an Adjunct to Intensive Behavioral Therapy on Body Weight in Adults With Overweight or Obesity: The STEP 3 Randomized Clinical Trial. JAMA. 2021;325:1403-1413. PubMed. Accessed Oct 2026.
4. Garvey WT, Batterham RL, Bhatta M, et al. Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial. Nat Med. 2022;28:2083-2091. PubMed. Accessed Oct 2026.
5. Wilding JPH, Batterham RL, Davies M, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes Obes Metab. 2022;24:1553-1564. PubMed. Accessed Oct 2026.
6. Ryan DH, Lingvay I, Deanfield J, et al. Long-term weight loss effects of semaglutide in obesity without diabetes in the SELECT trial. Nat Med. 2024;30:2049-2057. PubMed. Accessed Oct 2026.
7. DailyMed. Wegovy (semaglutide) injection and tablet prescribing information and Medication Guide, revised 06/2026. National Library of Medicine, NIH. dailymed.nlm.nih.gov. Accessed Oct 2026.

This article is for general information. It is not medical advice and it is not a recommendation for any particular treatment. Whether a treatment is appropriate for you is a decision for a licensed clinician who has reviewed your health history and current medications.