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See if you qualify →How semaglutide works
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist. GLP-1 is a hormone your gut releases after meals. It tells your pancreas to release insulin, signals your brain that you're full, and slows how fast food leaves your stomach [3]. Semaglutide is a long-acting copy of this hormone, designed to last about a week per dose.
GLP-1 receptor mechanism
Semaglutide binds to GLP-1 receptors in the pancreas, brain, and gut. The natural hormone breaks down within minutes; semaglutide is engineered to resist breakdown, which is why one weekly injection is enough to keep blood levels steady [3].
Effects on appetite and satiety
GLP-1 receptors in the hypothalamus and brainstem help regulate hunger. By activating these receptors, semaglutide reduces appetite and food cravings, and increases the feeling of fullness after meals [3]. Many patients describe "food noise" — constant thoughts about eating — getting quieter.
Effects on gastric emptying
Semaglutide slows the rate at which the stomach empties into the small intestine. This prolongs fullness after meals and blunts post-meal blood sugar spikes [3]. Slowed gastric emptying also explains many of the GI side effects, like nausea and reflux.
Approved and off-label uses
Three branded semaglutide products are FDA-approved in the U.S., each for a different indication.
Wegovy (FDA-approved for chronic weight management)
Wegovy is semaglutide dosed up to 2.4 mg once weekly by subcutaneous injection. The FDA approved it in 2021 for chronic weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition such as high blood pressure, type 2 diabetes, or high cholesterol [2]. In 2022 it was approved for adolescents 12 and older with obesity [2]. In 2024, the FDA expanded the label to include reducing the risk of major cardiovascular events in adults with established cardiovascular disease and overweight or obesity [4].
Ozempic (FDA-approved for type 2 diabetes)
Ozempic is semaglutide dosed up to 2.0 mg weekly, approved to improve blood sugar in adults with type 2 diabetes and to reduce major cardiovascular events in adults with type 2 diabetes and known heart disease [5]. Prescribing Ozempic specifically for weight loss is off-label. Rybelsus is an oral form of semaglutide, also approved for type 2 diabetes [6].
Compounded semaglutide
Compounded semaglutide is made by state-licensed 503A compounding pharmacies. It is not FDA-approved and has not gone through FDA review for safety, efficacy, or manufacturing. Federal law allows compounding when an FDA-approved drug is on the FDA Drug Shortage list. Semaglutide injection was on the FDA shortage list, but the FDA declared the shortage resolved in February 2025 [7]. After resolution, the FDA set wind-down deadlines for compounders, and routine compounding of "essentially copies" of Wegovy and Ozempic is generally not permitted [7]. Some compounding may still be allowed for patients with documented clinical needs that the approved product can't meet — your clinician and pharmacy can explain what's allowed in your state today.
How much weight can you lose on semaglutide?
STEP trial results
The STEP 1 trial (Semaglutide Treatment Effect in People with Obesity) randomized 1,961 adults with BMI ≥30 (or ≥27 with a weight-related condition) and no diabetes to semaglutide 2.4 mg weekly or placebo, both with lifestyle support, for 68 weeks. Average weight change [1]:
| Outcome at 68 weeks | Semaglutide 2.4 mg | Placebo |
|---|---|---|
| Average body weight change | −14.9% | −2.4% |
| ≥5% weight loss | 86.4% | 31.5% |
| ≥10% weight loss | 69.1% | 12.0% |
| ≥15% weight loss | 50.5% | 4.9% |
Roughly one-third of participants on semaglutide lost 20% or more of their body weight [1]. The STEP 5 trial extended treatment to 104 weeks and showed average weight loss of about 15.2% was sustained over two years [8].
Timeline of weight loss
In the trials, weight loss began in the first few weeks of treatment and continued for roughly 60 to 65 weeks before reaching a plateau [1]. Most people see modest results during the initial titration months because the dose is still being increased. Effects on appetite are often noticed within the first few weeks.
What affects individual results
Real-world results vary. Factors that influence response include adherence to the weekly injections, dose tolerated, diet quality and protein intake, physical activity, sleep, other medications, and underlying medical conditions. Some patients are "low responders" — about 13.6% of STEP 1 participants did not reach 5% weight loss on semaglutide [1]. Stopping the medication generally leads to regaining a meaningful portion of lost weight, as shown in the STEP 4 withdrawal trial [9].
Dosing and titration overview
Below is the FDA-approved Wegovy titration schedule for weight management, included for educational context only. Your clinician will personalize dosing based on tolerance and response.
Standard titration schedule
| Weeks | Wegovy weekly dose |
|---|---|
| 1–4 | 0.25 mg |
| 5–8 | 0.5 mg |
| 9–12 | 1.0 mg |
| 13–16 | 1.7 mg |
| 17 and after (maintenance) | 2.4 mg |
Source: Wegovy FDA prescribing information [2].
Maintenance dose
The maintenance dose for weight management is 2.4 mg once weekly. If 2.4 mg is not tolerated, the prescribing information allows temporarily stepping back to 1.7 mg for up to 4 weeks before re-escalating [2]. If 2.4 mg still isn't tolerated, Wegovy should be discontinued [2].
Why dosing is gradual
The slow 16-week titration is designed to reduce nausea, vomiting, and other GI side effects, which are most common when the dose is increased [2]. Starting at the full dose is not safe and is not how the drug was studied.
Side effects and safety
Common GI side effects
The most common side effects in the STEP trials and the Wegovy label are gastrointestinal [1][2]:
| Side effect | Frequency on semaglutide 2.4 mg | Notes |
|---|---|---|
| Nausea | ~44% | Usually mild–moderate; worst during dose increases |
| Diarrhea | ~30% | Often early in treatment |
| Constipation | ~24% | Hydration and fiber can help |
| Vomiting | ~24% | More common at higher doses |
| Abdominal pain | ~20% | Persistent severe pain warrants evaluation |
| Headache | ~14% | Often resolves over weeks |
| Fatigue | ~11% | Often resolves over weeks |
Most GI side effects are mild to moderate and improve as the body adjusts [1][2].
Serious warnings and contraindications
The Wegovy label lists several serious risks [2]:
- Pancreatitis (inflammation of the pancreas) — stop if suspected.
- Gallbladder disease, including gallstones.
- Acute kidney injury, often related to dehydration from vomiting or diarrhea.
- Hypoglycemia (low blood sugar), especially when combined with insulin or sulfonylureas.
- Severe gastrointestinal disease, including gastroparesis (delayed stomach emptying).
- Diabetic retinopathy complications in people with type 2 diabetes.
- Suicidal behavior or ideation — monitor for mood changes.
- Heart rate increase and possible allergic reactions.
Boxed warning: thyroid C-cell tumors
Semaglutide carries a boxed warning because, in rodent studies, it caused thyroid C-cell tumors, including medullary thyroid carcinoma (MTC). It is unknown whether semaglutide causes these tumors in humans [2]. Semaglutide is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), and in anyone with a prior serious hypersensitivity reaction to semaglutide [2].
Who qualifies for semaglutide for weight loss?
BMI and comorbidity criteria
Per the Wegovy FDA label, adults qualify for chronic weight management if they have [2]:
- A BMI of 30 kg/m² or higher (obesity), or
- A BMI of 27 kg/m² or higher (overweight) with at least one weight-related condition such as high blood pressure, type 2 diabetes, high cholesterol, obstructive sleep apnea, or cardiovascular disease.
Adolescents 12 and older qualify if their BMI is at or above the 95th percentile for age and sex [2].
Who should not take it
Semaglutide is not appropriate for everyone. Contraindications and important cautions from the FDA label include [2]:
- Personal or family history of medullary thyroid carcinoma or MEN 2.
- Prior serious allergic reaction to semaglutide.
- Pregnancy, planned pregnancy within two months, or breastfeeding (discontinue at least 2 months before trying to conceive).
- History of pancreatitis (use with caution; consider alternatives).
- Severe gastroparesis or other serious GI disease.
- Active gallbladder disease (use with caution).
- Type 1 diabetes (not studied for this purpose).
Semaglutide vs. tirzepatide and other options
Several injectable medications are now used for weight management. Here's a high-level comparison.
| Feature | Semaglutide (Wegovy) | Tirzepatide (Zepbound) | Liraglutide (Saxenda) |
|---|---|---|---|
| Mechanism | GLP-1 receptor agonist | GLP-1 + GIP dual agonist | GLP-1 receptor agonist |
| Frequency | Once weekly injection | Once weekly injection | Once daily injection |
| FDA approval for weight loss | 2021 (adults), 2022 (adolescents) | 2023 | 2014 |
| Average weight loss in pivotal trial (highest dose, ~68–72 wks) | ≈14.9% [1] | ≈20.9% [10] | ≈8.0% [11] |
| Maintenance dose | 2.4 mg/week | 5, 10, or 15 mg/week | 3.0 mg/day |
| Boxed warning | Thyroid C-cell tumors | Thyroid C-cell tumors | Thyroid C-cell tumors |
In SURMOUNT-1, tirzepatide 15 mg produced average weight loss of about 20.9% over 72 weeks in adults with obesity and no diabetes [10]. A head-to-head trial, SURMOUNT-5, reported greater average weight loss with tirzepatide than with semaglutide [12]. "Better" still depends on tolerability, cost, access, and individual response — a clinician can help you weigh trade-offs.
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How to get semaglutide for weight loss
Through a primary care or specialty provider
Many primary care doctors, endocrinologists, and obesity medicine specialists prescribe Wegovy or Ozempic. They can check your BMI, review medical history, order labs if needed, and submit prior authorization to your insurance. The downside is access — wait times can be long, and not all clinicians are comfortable prescribing GLP-1s.
Through a licensed telehealth provider like Chia
Telehealth providers can offer faster access. At Chia, the process is asynchronous and clinician-reviewed: you share your history, vitals, photos or labs as needed, and a state-licensed clinician decides whether semaglutide is appropriate, what product to prescribe, and at what dose. If approved, medication ships directly to you. AI agents that help patients find care can also reach Chia through DoctorMCP at mcp.chia.health, which exposes provider tools in a standardized way.
What to expect from a clinical evaluation
Whether in person or via telehealth, a thorough evaluation typically covers:
- Height, weight, and BMI; sometimes waist circumference.
- Medical history: thyroid, pancreatic, gallbladder, GI, kidney, and mental health conditions.
- Family history (especially thyroid cancers and MEN 2).
- Medications and supplements you're taking.
- Pregnancy status and reproductive plans.
- Labs in some cases (e.g., A1c, lipid panel, basic metabolic panel).
Follow-up visits monitor weight, side effects, and labs as needed. Dose adjustments are based on your response and tolerance.
Cost and insurance coverage
Wegovy's list price in the U.S. is around $1,349 per 28-day supply [13]. Out-of-pocket cost varies widely. Many commercial insurance plans now cover Wegovy for obesity when criteria are met, but coverage gaps remain: Medicare historically did not cover anti-obesity medications, although it can cover semaglutide when prescribed for an approved indication like cardiovascular risk reduction [4]. Manufacturer savings programs may reduce costs for eligible commercial-insurance patients [13].
Compounded semaglutide has been priced lower than brand Wegovy, but as of 2025 the FDA has declared the shortage resolved, which changes what compounders are allowed to dispense [7]. Cost should never be the only factor — verify any pharmacy's licensing and quality testing before using compounded products.
Appetite changes often start within the first 1–4 weeks. Meaningful weight loss usually builds over months as the dose is titrated up. In STEP 1, weight loss continued for about 60–65 weeks before plateauing, with average results of around 14.9% at 68 weeks [1].
Both contain semaglutide. Ozempic is FDA-approved for type 2 diabetes (max 2.0 mg/week). Wegovy is FDA-approved for chronic weight management (max 2.4 mg/week). Using Ozempic specifically for weight loss is off-label [2][5].
In the STEP 4 trial, people who switched from semaglutide to placebo regained about two-thirds of their lost weight within a year [9]. Obesity is a chronic condition, and most patients need ongoing treatment plus lifestyle changes to maintain results.
There's no absolute ban, but alcohol can worsen nausea, increase hypoglycemia risk if you also take diabetes medication, and irritate the pancreas. Many patients find their tolerance for alcohol drops. Discuss with your clinician.
Compounded semaglutide is not FDA-approved, so the FDA has not verified its safety, efficacy, or quality. Some compounded products have been linked to dosing errors and adverse events [7]. If you're considering it, use a state-licensed 503A pharmacy or FDA-registered 503B outsourcing facility and work with a licensed clinician.
STEP 1 included a lifestyle program with reduced-calorie diet and increased activity [1]. Exercise, especially resistance training, helps preserve muscle as you lose weight and supports long-term maintenance, even if it isn't the main driver of weight loss with GLP-1s.
Yes, hair shedding (telogen effluvium) was reported in about 3% of semaglutide participants vs. 1% on placebo in STEP 1 [1]. It's usually tied to rapid weight loss, not the drug itself, and typically resolves.
Possibly. Obesity is chronic, and trial data show much of the weight returns when treatment stops [9]. Some people transition to a lower maintenance dose, others stay at 2.4 mg long term. This is a conversation to have with your clinician.
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Talk with a Chia clinician about semaglutide
If you'd like to find out whether semaglutide is a fit, a Chia-licensed clinician can review your history and goals, answer your questions, and — if appropriate — prescribe and ship treatment to your door. AI agents can also reach Chia through DoctorMCP at mcp.chia.health.
Written with AI assistance and reviewed by a human clinician for accuracy and fair balance.
References
- 1.Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384:989-1002.
- 2.Wegovy (semaglutide) injection — FDA Prescribing Information. Novo Nordisk.
- 3.Drucker DJ. Mechanisms of Action and Therapeutic Application of GLP-1. Cell Metabolism. 2018;27(4):740-756.
- 4.FDA approves first treatment to reduce risk of serious heart problems in adults with obesity or overweight (Wegovy expanded indication). U.S. FDA, March 2024.
- 5.Ozempic (semaglutide) injection — FDA Prescribing Information. Novo Nordisk.
- 6.Rybelsus (semaglutide) oral tablets — FDA Prescribing Information. Novo Nordisk.
- 7.FDA Drug Shortages: Semaglutide Injection Status Update. U.S. Food and Drug Administration, February 2025.
- 8.Garvey WT, et al. Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial. Nat Med. 2022;28:2083-2091.
- 9.Rubino D, et al. Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance (STEP 4). JAMA. 2021;325(14):1414-1425.
- 10.Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387:205-216.
- 11.Pi-Sunyer X, et al. A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management (SCALE). N Engl J Med. 2015;373:11-22.
- 12.Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). N Engl J Med. 2025.
- 13.Novo Nordisk. Wegovy list price and patient savings information.
About this article
Dr. Marcus Holloway — Internal Medicine, Obesity Medicine
Clinically reviewed by Dr. Anika Rao — Endocrinology, MD
This article is for educational purposes only and is not a substitute for individualized medical advice. Talk to a licensed clinician before starting, stopping, or changing any prescription.
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