Last updated November 2, 2026 · Reviewed by the Gala Health team
Why it takes weeks: the titration schedule
GLP-1 medicines for weight loss are not started at the full dose. The labels use stepwise dose escalation to reduce the risk of digestive side effects, so the dose that produced the trial results is reached only after several weeks.
| Wegovy (semaglutide) injection | Zepbound (tirzepatide) | |
|---|---|---|
| Starting dose | 0.25 mg weekly for weeks 1 to 4 | 2.5 mg weekly for 4 weeks (initiation dose, not a maintenance dose) |
| Next steps | 0.5 mg weeks 5 to 8, 1 mg weeks 9 to 12, 1.7 mg weeks 13 to 16 | 5 mg after 4 weeks, then raised in 2.5 mg steps after at least 4 weeks on each dose |
| Maintenance | From week 17: 1.7 mg or 2.4 mg (2.4 mg recommended) | 5 mg, 10 mg or 15 mg weekly |
| If a dose is not tolerated | Consider delaying dose escalation for 4 weeks | Consider a lower maintenance dose |
Schedules are from each brand-name label. Compounded products have their own dosing instructions from the prescriber and pharmacy. The Wegovy label also describes a higher 7.2 mg option for people who tolerate 2.4 mg for at least 4 weeks and need additional weight reduction. See our GLP-1 dosing schedule guide.
When do appetite changes start?
Both labels say these drugs act on appetite. The Wegovy label states that GLP-1 is a physiological regulator of appetite and caloric intake and that semaglutide decreases calorie intake, likely through its effect on appetite. The Zepbound label says the same of tirzepatide.
The labels do not give a day or week by which appetite should change, so we cannot say exactly when you will notice it. Because the starting doses are low, some people notice little at first and more as the dose rises, and digestive effects are most likely during escalation. Your provider can adjust the plan if side effects are hard to manage.
Wegovy (semaglutide): STEP 1 and STEP 4
In STEP 1, a trial of 1,961 adults with overweight or obesity and without diabetes, average body weight fell 14.9% from baseline at week 68 with Wegovy (semaglutide 2.4 mg) plus lifestyle intervention, compared with 2.4% with placebo. That is an average. In the same trial, 86.4% of people on semaglutide lost at least 5% of body weight, 69.1% lost at least 10%, and 50.5% lost at least 15%, versus 31.5%, 12.0% and 4.9% on placebo.
STEP 4 offers an earlier snapshot. All 902 participants received semaglutide during a 20-week run-in (16 weeks of dose escalation plus 4 weeks at 2.4 mg), and those who reached 2.4 mg lost a mean of 10.6% of body weight over those 20 weeks. This does not mean 10.6% is typical at week 20 in every setting, since participants all went through the same run-in, but it shows that substantial loss was seen before the 68-week endpoint.
Zepbound (tirzepatide): SURMOUNT-1 and SURMOUNT-4
SURMOUNT-1 enrolled 2,539 adults with obesity (or overweight with a weight-related complication), excluding diabetes, for 72 weeks including a 20-week dose-escalation period. Mean weight change at week 72 was -15.0% with Zepbound 5 mg, -19.5% with 10 mg and -20.9% with 15 mg, compared with -3.1% with placebo. The Zepbound label reports the same figures for its Study 1.
In SURMOUNT-4, adults took tirzepatide at the maximum tolerated dose (10 mg or 15 mg) in a 36-week open-label lead-in. The 670 participants who were then randomized had lost a mean of 20.9% of body weight by week 36.
| Trial | Brand drug | Time point | Average weight change |
|---|---|---|---|
| STEP 4 run-in | Wegovy (semaglutide) | Week 20 | -10.6% |
| STEP 1 | Wegovy (semaglutide 2.4 mg) | Week 68 | -14.9% (placebo -2.4%) |
| SURMOUNT-4 lead-in | Zepbound (tirzepatide) | Week 36 | -20.9% |
| SURMOUNT-1 | Zepbound (tirzepatide 5 / 10 / 15 mg) | Week 72 | -15.0% / -19.5% / -20.9% (placebo -3.1%) |
The trials differ in design, populations and doses, so the rows should not be read as a head-to-head comparison. These are averages for the brand-name drugs and do not describe compounded versions or Gala patients.
Plateaus and the shape of weight loss
Weight loss on a GLP-1 is not a straight line. A 2025 joint advisory from four U.S. nutrition and obesity societies, which reviewed the major trials, says weight reduction is generally more rapid during the first 6 months and slows afterward, with relative plateauing at about 18 months. It adds that when treatment continues, weight reduction is sustained for at least 4 years in controlled and observational studies.
A plateau is a slower rate of loss, and it often reflects the body adapting at a lower weight. It can also be a prompt to check dose, side effects, sleep, activity and food intake with your provider. Our guide on what to eat on a GLP-1 covers the nutrition side. Do not raise your dose or change your injection schedule on your own.
When should you reassess with your provider?
The labels do not set a fixed date by which you must lose a certain amount. They tell providers to consider treatment response and tolerability when choosing the maintenance dose, and to consider a lower maintenance dose if a dose is not tolerated. That means a check-in is a conversation, not a pass-or-fail test.
- If side effects are severe or do not go away, message your care team early rather than waiting for the next step-up.
- If your weight has not changed after you have been at a maintenance dose for a while, ask your provider whether to adjust the dose, review other factors, or consider a different medicine.
- If you miss several doses, ask before restarting, since the Wegovy label says to reinitiate dose escalation at a lower dose if two or more consecutive doses are missed.
Logging your doses in the Gala GLP-1 app gives your provider a clearer picture when you ask these questions.
How Gala's care team helps
Compounded medications are not FDA-approved. Gala offers compounded semaglutide, compounded tirzepatide and brand-name Ozempic®. A licensed provider reviews your online assessment and prescribes only if it is appropriate for you. If prescribed, your medication ships to your home, you can message your care team about progress and side effects, and your provider can adjust your dose.
To see whether a GLP-1 option may be right for you, start your online GLP-1 assessment, or explore the weight loss hub. For a side-by-side look at the two ingredients, see semaglutide vs tirzepatide, and read about compounded GLP-1 medications.
This article is for information only and is not medical advice. Talk to your healthcare provider about your expected progress and treatment plan.
Frequently asked questions
How long does it take to lose weight on a GLP-1?
It depends on the person and the dose. In the STEP 1 trial of Wegovy (semaglutide 2.4 mg), average weight change was 14.9% at week 68, and in the SURMOUNT-1 trial of Zepbound (tirzepatide), it was 15.0% to 20.9% at week 72 depending on dose. Both trials raised the dose gradually over about 16 to 20 weeks.
Will I notice appetite changes after the first injection?
The labels do not say when appetite changes begin. They state that these medicines decrease calorie intake, likely through effects on appetite, and they start at low doses that are raised every few weeks. Some people notice effects early and others later. Tell your provider if you notice no change or if side effects are difficult.
Why is my weight loss slowing down?
A 2025 joint advisory from four U.S. nutrition and obesity societies says weight reduction is generally faster in the first 6 months and then slows, with relative plateauing at around 18 months. Slower loss is common, but check in with your provider about your dose, food intake, activity and sleep rather than changing your dose yourself.
How long until I reach the full dose?
On the Wegovy label, the dose rises every 4 weeks from 0.25 mg, reaching the 1.7 mg step at week 13 and a maintenance dose from week 17. The Zepbound label starts at 2.5 mg for 4 weeks and then raises the dose in 2.5 mg steps after at least 4 weeks on each dose, up to 15 mg. Compounded products follow your prescriber's schedule.
What if I do not lose weight on a GLP-1?
Individual results vary, and averages in trials hide a wide range. Talk to your provider, who can check whether the dose is right, review side effects and lifestyle factors, and discuss other options. The labels ask providers to weigh response and tolerability, and they do not set a single pass-or-fail date.
Ready to talk to a provider?
Your answers go to a licensed provider, who decides whether treatment is right for you. Learn more about Weight Loss.
Sources
- Novo Nordisk. WEGOVY (semaglutide) prescribing information. FDA-approved label.
- Eli Lilly. ZEPBOUND (tirzepatide) prescribing information. FDA-approved label.
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021.
- Rubino D, et al. Effect of continued weekly subcutaneous semaglutide vs placebo on weight loss maintenance (STEP 4). JAMA. 2021.
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022.
- Aronne LJ, et al. Continued treatment with tirzepatide for maintenance of weight reduction in adults with obesity (SURMOUNT-4). JAMA. 2024.
- Mozaffarian D, et al. Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory. Obesity Pillars. 2025.
This article is for general information and is not medical advice. Talk to a licensed provider about your own health.