How does semaglutide work for weight loss?
You will lose weight over the long-term with semaglutide because you will eat less, and feel fuller when you do eat. Semaglutide does this by targeting an area in the brain (called GLP-1 receptors) that help to regulate your appetite and how much you eat. It closely mimics a natural hormone in the body called incretin, which is made primarily in our digestive tract.
Semaglutide is used as a long-term weight loss treatment in addition to a healthy diet and exercise to help promote weight loss. Semaglutide (Wegovy and Ozempic) are also approved to help protect the heart in patients with heart disease.
In addition, Ozempic is approved is as treatment for type 2 diabetes to control blood sugar (glucose) levels and to reduce the risk of worsening kidney disease, kidney failure (end-stage kidney disease) and cardiovascular death in adults with type 2 diabetes and chronic kidney disease.
What is the mechanism of action of semaglutide?
Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist and occupies the GLP-1 receptor in the brain that regulates appetite.
It should not be used with other semaglutide-containing products (such as Ozempic, Rybelsus) or other GLP-1 receptor agonist medicines.
Semaglutide helps people to lose weight by:
- Targeting the brain centers that regulate appetite, especially after eating, which may help you eat less.
- Slowing down how quickly food leaves your stomach, which makes you feel fuller for longer.
- It's long-term effects. Semaglutide treatment is recommended for long-term use if it’s effective for you. With continued use, semaglutide has been shown in studies to help people lose about 15% of their weight (about 35 lb on average) and keep it off for over two years.
Who can use semaglutide for weight loss?
Semaglutide (Wegovy) is used, in addition to a low-calorie diet and increased physical exercise:
- for adults and children aged 12 years and older with obesity, or some
adults with excess weight (overweight) who also have weight-related medical
problems to lose weight and keep the weight off. - to reduce the risk of major cardiovascular events such as death, heart attack, or stroke in adults with known heart disease and with either obesity or overweight.
Other prescription drugs that also contain semaglutide are Ozempic (injection) or Rybelsus (oral tablets). These brands are not specifically approved for weight loss, but can lead to weight loss when used for their indications.
Related questions
- Ozempic Side Effects to Watch For
- Wegovy vs Ozempic: Which is Right for You?
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How long does semaglutide take to work?
You may see some weight loss in the 4 weeks of semaglutide treatment, but the full effect can take several months. After 68 weeks, adults lost an average of about 35 lbs (15.9 kg), or 15% of their weight, and these results were sustained at 2 years.
Your doctor will slowly increase your dose when you start treatment to help lessen stomach side effects like nausea and diarrhea. It typically takes about 17 weeks to reach your final maintenance dose of semaglutide.
- Studies conducted by the manufacturer over 68 weeks show that, on average, adults using semaglutide lost about 35 lbs (15.9 kg), or about 15% of their body weight. In contrast, 31% of people using a placebo (inactive treatment) lost about 6 lbs (2.7 kg), or about 2.5% of their body weight.
- In studies extended to 2 years (104 weeks), patients taking semaglutide (Wegovy) achieved about a 35 lb weight reduction vs. a 6 lb weight loss (15% vs. 2.6%) in people using the placebo (an injection with no medicine).
- In children 12 years and older, semaglutide reduced their body mass index (BMI) by 16.1% after 68 weeks compared to a 0.6% reduction in the placebo group. Plus, the BMI was reduced by at least 5% in 77% of children receiving semaglutide compared to 20% receiving a placebo.
This is not all the information you need to know about semaglutide (Wegovy) for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.
References
- FDA Approves First Treatment to Reduce Risk of Serious Heart Problems Specifically in Adults with Obesity or Overweight. FDA. March 8, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-treatment-reduce-risk-serious-heart-problems-specifically-adults-obesity-or
- Wegovy product information. Revised: 12/2022. Novo Nordisk. Plainsboro, NJ. Accessed Apr 10, 2023 at https://www.novo-pi.com/wegovy.pdf
- Wegovy.com. Wegovy mechanism of action. Novo Nordisk. https://www.novomedlink.com/obesity/products/treatments/wegovy/about-wegovy/how-wegovy-works.html
Read next
Which GLP-1 drug is best for weight loss?
The most effective GLP-1 drug for weight loss currently (as of mid-2025) is tirzepatide, marketed under the names Zepbound (for weight loss) and Mounjaro (for diabetes).
Continue reading
Why am I not losing weight on Ozempic?
Although Ozempic is not FDA-approved for weight loss, over 86% of people lose at least 5% of their body weight in trials that have studied semaglutide, the active ingredient of Ozempic. But the same clinical trials also show that just under 14% don’t lose weight, and some may even gain weight. Continue reading
Does Ozempic cause muscle loss and how to prevent it?
Clinical trials have shown GLP-1 agonist drugs like semaglutide (Ozempic) can lead to a 13.9% loss of lean muscle mass (equal to a 6.9 kg or 15 lb) during treatment. Strategies to help prevent muscle loss include regular strength (resistance) training, aerobic exercise and adequate dietary protein, fluid and nutrient intake.
Continue readingSee also:
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Drug information
- Semaglutide Information for Consumers
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