Guide
What is GLP-1? How it works for weight loss
By the TreatmentMD editorial team
Medically reviewed by Christopher Stephenson, MD
Key takeaways
- GLP-1 medications mimic a gut hormone that helps control appetite and blood sugar.
- Some GLP-1 medications are FDA-approved for type 2 diabetes, obesity, and weight management.
- How much weight you lose depends on the specific drug, the dose, and your own body. Your provider can help you set realistic expectations.
By the TreatmentMD editorial team
You've seen headlines about "GLP-1 drugs" for weight loss, and you might be wondering what GLP-1 actually is and how it fits into your wellness options.
Read below to learn more about the hormone behind the headlines, what the medications actually do, and how to know whether it might be right for you.
01The basics
What is GLP-1?
GLP-1 stands for glucagon-like peptide-1. It's a hormone your gut releases naturally after you eat.1SourceSourceMayo Clinic Diet. "How does semaglutide work?" 2024.Open the source All sources
Its job is to send a signal to your brain that you're full and to slow digestion, helping you feel full longer.2Cleveland ClinicSourceCleveland Clinic. "GLP-1 Agonists: What They Are, How They Work & Side Effects." 2023.Open the source All sources
GLP-1 medications act like this hormone but can last much longer in your body.
Semaglutide (the active ingredient in Ozempic® and Wegovy®) and tirzepatide (the active ingredient in Mounjaro® and Zepbound®) are the two most talked-about examples.
02How it works
How it works
GLP-1 medications work on a few fronts at once.
In your brain, they act on hunger centers to reduce appetite and quiet "food noise," so you feel satiated faster.2Cleveland ClinicSourceCleveland Clinic. "GLP-1 Agonists: What They Are, How They Work & Side Effects." 2023.Open the source All sources
In your stomach, they slow digestion, helping you feel full for a longer time.
Together, these effects usually add up to eating less without constant willpower battles.
Recent studies suggest appetite and digestion effects drive weight loss.2Cleveland ClinicSourceCleveland Clinic. "GLP-1 Agonists: What They Are, How They Work & Side Effects." 2023.Open the source All sources
03Who it's for
Who is this best for?
Different GLP-1 medications are approved for various needs.
Wegovy® and Zepbound® are FDA-approved for chronic weight management in adults with obesity or overweight adults with weight-related conditions such as high blood pressure.
Ozempic® and Mounjaro® are FDA-approved for type 2 diabetes and can induce weight loss. In specific cases, a healthcare provider may prescribe these medications for weight management.
Insurance coverage may vary depending on the type of GLP-1 medication and its intended use.
04Results
Effectiveness
In a large clinical trial, adults taking semaglutide (the Wegovy® dose) lost about 15% of their starting body weight on average over roughly a year and a half, compared to about 2% for those on a placebo.3The New England Journal of MedicineRandomized trial · 2021STEP 1Mean body weight fell 14.9 percent on semaglutide against 2.4 percent on placebo over 68 weeks.1,961 people · 68 weeks. Adults with BMI 30 or above, or 27 or above with a weight-related comorbidity, without diabetes.Once-weekly semaglutide in adults with overweight or obesity. Wilding JPH, et al., 2021.Read the study All sources
In a separate trial of tirzepatide (the Zepbound® dose), average weight loss ranged from about 15% to 21% over about a year and a half.4The New England Journal of MedicineRandomized trial · 2022SURMOUNT-1Mean body weight fell 20.9 percent at the 15 mg dose against 3.1 percent on placebo over 72 weeks.2,539 people · 72 weeks. Adults with BMI 30 or above, or 27 or above with at least one weight-related complication, without diabetes.Tirzepatide once weekly for the treatment of obesity. Jastreboff AM, et al., 2022.Read the study All sources
Results vary widely from person to person and with the prescribed dosage.
It's also worth knowing that these medications tend to work mainly while you are actively taking them.
In one study, people who stopped semaglutide regained much of the weight they'd lost within a year.5Diabetes, Obesity and MetabolismRandomized trial · 2022STEP 1 extensionA year after stopping semaglutide, people had regained about two-thirds of the weight they lost, and were still 5.6% lighter on average than when they started.327 people · 120 weeks. Adults from STEP 1, followed for a year after treatment stopped.Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Wilding JPH, et al., 2022.Read the study All sources
Many providers treat this as a long-term medication rather than a short course, similar to how you'd manage high blood pressure.
05Taking it
How it's taken
Most GLP-1 medications for weight loss are given as a once-weekly injection under the skin, usually in the belly, thigh, or upper arm.2Cleveland ClinicSourceCleveland Clinic. "GLP-1 Agonists: What They Are, How They Work & Side Effects." 2023.Open the source All sources
You can do this yourself at home using a pre-filled pen, or have someone help you.
Doses start low and increase gradually over weeks or months, which helps your body adjust and limits side effects.
A once-daily oral version of semaglutide is also FDA-approved, giving people another option.
06Side effects
Side effects & safety
Common side effects are mostly digestive and tend to be strongest while your dose is increasing:
07Cost
Cost & access
Brand-name GLP-1 medications can have higher out-of-pocket costs, running over $1,000 a month.6SourceSourceGoodRx. "Zepbound Cost" (pricing data); JumpstartMD GLP-1 cost and coverage hub, 2026.All sources
What you pay depends heavily on your insurance and where the drug falls on your plan's formulary.
Many commercial plans cover Wegovy® or Zepbound® for weight loss only if you meet BMI or health-condition criteria, and coverage for Ozempic® or Mounjaro® is generally limited to diabetes care.
Manufacturer savings programs and direct-to-consumer pharmacy programs can lower the price for people who qualify, but availability and terms change often, so it's worth checking current offers directly with the manufacturer or your pharmacy.
08Getting started
Is it right for you? How to get started
There's no single "best" GLP-1 medication. It depends on your health history, your goals, your insurance, and how your body responds.
A licensed provider can look at your full picture, including any conditions that would rule a medication in or out, and help you decide whether a GLP-1 medication makes sense for you, alongside diet and exercise changes.
Frequently asked questions.
Can I take a GLP-1 medication if I don't have diabetes?
Yes, if you're prescribed one that's approved for weight management, such as Wegovy® (semaglutide) or Zepbound® (tirzepatide), and you meet the criteria for use.
Do I have to stay on it forever?
Many people regain weight after stopping, so providers often discuss it as a long-term treatment, similar to medication for a chronic condition.
Your provider can talk through what's realistic for you.
Will insurance cover GLP-1 medications?
It depends on your insurance plan and the specific drug's approved use.
Weight-loss-approved drugs like Wegovy® (semaglutide) and Zepbound® (tirzepatide) are more likely to require meeting BMI or health criteria for coverage.
The bottom line
GLP-1 is a natural hormone, and GLP-1 medications use that same biology to help reduce appetite and support weight loss.
Results, side effects, and costs vary by drug and by person, so this isn't a one-size-fits-all decision.
Your provider is the best partner for sorting through which option, if any, fits your health and your goals.
By the TreatmentMD editorial team
Medical disclaimerThis content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before starting any weight-loss program or medication. Individual results may vary.
Sources
- 1Mayo Clinic Diet. "How does semaglutide work?" 2024. diet.mayoclinic.org
- 2Cleveland Clinic. "GLP-1 Agonists: What They Are, How They Work & Side Effects." 2023. clevelandclinic.org
- 3Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384(11):989-1002. doi.org
- 4Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205-216. doi.org
- 5Wilding, J.P.H., et al. "Weight regain and cardiometabolic effects after withdrawal of semaglutide." Diabetes, Obesity and Metabolism, 2022. doi.org
- 6GoodRx. "Zepbound Cost" (pricing data); JumpstartMD GLP-1 cost and coverage hub, 2026.
Product information
- Zepbound® (tirzepatide) is a prescription-only injectable medication FDA-approved for chronic weight management in adults with obesity, or adults with overweight who have at least one weight-related medical condition. It is also approved for the treatment of moderate to severe obstructive sleep apnea in adults with obesity, and should be used in combination with a reduced-calorie diet and increased physical activity.
- Ozempic® (semaglutide) is a prescription-only injectable medication approved by the U.S. Food and Drug Administration (FDA) for the treatment of type 2 diabetes. It is not FDA-approved for weight loss; however, weight reduction has been observed in some individuals with type 2 diabetes using the medication.
- Mounjaro® (tirzepatide) is a prescription-only injectable medication FDA-approved for the treatment of type 2 diabetes. It is not FDA-approved for weight loss; however, weight reduction has been observed in some individuals using the medication.
- Wegovy® (semaglutide) is a prescription-only injectable medication FDA-approved for chronic weight management in adults with obesity, or adults with at least one weight-related medical condition, when used alongside a reduced-calorie diet and increased physical activity.
- All medications require a medical evaluation and prescription from a licensed healthcare provider. Individual results may vary.
Important safety information
- Compounded semaglutide and tirzepatide are prepared by state-licensed pharmacies and are not FDA approved. The FDA does not review their safety, effectiveness or quality, and clinical trial results for brand-name drugs do not carry over to them.
- Semaglutide and tirzepatide carry a boxed warning for a risk of thyroid C-cell tumors, based on animal studies, and are not for anyone with a personal or family history of medullary thyroid carcinoma (MTC) or MEN2, or who is pregnant. Other warnings include pancreatitis, gallbladder problems, and a higher risk of low blood sugar when combined with insulin or a sulfonylurea. The most common side effects are digestive, such as nausea, vomiting, diarrhea and constipation.
- This is a high-level summary, not a complete list. A licensed clinician will review your health history to decide whether a GLP-1 medication is right for you.
