What is GLP-1? GLP-1 (glucagon-like peptide-1) medications mimic a natural gut hormone that regulates appetite and blood sugar. FDA-approved options include semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). Clinical trials show 15-22% average weight loss with semaglutide and 20-25% with tirzepatide over 68-72 weeks. Common side effects include nausea, vomiting, and digestive issues that typically improve over time.
GLP-1 medications are some of the most talked-about drugs in years. But what exactly are they?
Key Points
- GLP-1 stands for glucagon-like peptide-1, a hormone your body naturally makes in the gut after eating
- GLP-1 medications mimic this hormone to reduce appetite, slow digestion, and help control blood sugar
- Average weight loss ranges from 15-25% depending on the medication, with tirzepatide showing slightly higher results
- Common side effects include nausea, vomiting, diarrhea, constipation, and fatigue
- FDA-approved for type 2 diabetes, obesity, and cardiovascular risk reduction in eligible patients
- Administered via weekly injection (or daily pill for Rybelsus), starting at low doses and increasing gradually
Statistics
- 15-18% average weight loss with semaglutide (Wegovy) over 68 weeks in clinical trials
- 20-22% average weight loss with tirzepatide (Zepbound) over 72 weeks in clinical trials
- 20-44% of users experience nausea, the most common side effect, which typically improves over time
- Wegovy FDA-approved for cardiovascular risk reduction in adults with established heart disease and obesity
Medical Review
This article was reviewed by the GLP Spot Medical Review Board to ensure accuracy and alignment with current clinical evidence. Last reviewed: April 2026.
What Does GLP-1 Mean?
GLP-1 stands for glucagon-like peptide-1. It's a hormone your body naturally makes in your gut after you eat.
GLP-1 medications mimic this hormone. They amplify what your body already does.
The natural GLP-1 hormone only lasts a couple of minutes in your bloodstream before an enzyme called DPP-4 breaks it down. The medications are engineered to resist this breakdown, so they stay active for hours or even days—depending on which one you're taking.
How They Work
GLP-1 meds do three main things:
- Tell your brain you're full – Reduces appetite and cravings by acting on appetite centers in the hypothalamus
- Slow your digestion – Food stays in your stomach longer, so you feel full longer
- Help control blood sugar – Tells your pancreas to release insulin when blood sugar is high, and reduces glucagon (a hormone that raises blood sugar)
Because they work with your body's natural systems rather than against them, GLP-1 medications tend to have fewer severe side effects than older weight loss drugs.
What GLP-1 Meds Treat
- Type 2 diabetes – Better blood sugar control with lower hypoglycemia risk than insulin
- Obesity – Significant weight loss (15-22% of body weight in clinical trials)
- Weight-related health conditions – High blood pressure, high cholesterol, sleep apnea
- Cardiovascular risk reduction – Wegovy is now FDA-approved to reduce risk of heart attack and stroke in adults with cardiovascular disease and obesity
The Main GLP-1 Medications
| Medication | Brand Names | How Often | Type | FDA Approved For |
|---|---|---|---|---|
| Semaglutide | Ozempic, Wegovy, Rybelsus | Weekly (daily for pill) | Injection or pill | Type 2 diabetes, weight loss, cardiovascular risk |
| Tirzepatide | Mounjaro, Zepbound | Weekly | Injection | Type 2 diabetes, weight loss |
| Liraglutide | Saxenda, Victoza | Daily | Injection | Weight loss, type 2 diabetes |
| Dulaglutide | Trulicity | Weekly | Injection | Type 2 diabetes |
| Exenatide | Byetta, Bydureon | Daily or weekly | Injection | Type 2 diabetes |
Key difference: Tirzepatide (Mounjaro, Zepbound) is technically a dual agonist—it activates both GLP-1 and GIP receptors, which may explain its slightly higher weight loss results compared to semaglutide alone.
For a detailed comparison, see our semaglutide vs. tirzepatide guide.
How Much Weight Can You Lose?
Results vary, but on average:
- Semaglutide (Wegovy): 15-18% of body weight over 68 weeks
- Tirzepatide (Zepbound): 20-22% of body weight over 72 weeks
- Liraglutide (Saxenda): 5-8% of body weight over 56 weeks
These numbers come from clinical trials. Your results may differ based on diet, exercise, starting weight, and individual biology.
Common Side Effects
Most side effects are stomach-related and improve over time:
- Nausea (most common, affects ~20-44% of users)
- Vomiting
- Diarrhea or constipation
- Stomach pain
- Reduced appetite
- Fatigue
See our side effects guide for more, and our side effects timeline for what to expect week by week.
Who Should NOT Take GLP-1
- People with a personal or family history of medullary thyroid carcinoma
- People with multiple endocrine neoplasia syndrome type 2
- Anyone allergic to the medication
- Pregnant or breastfeeding women (semaglutide should be stopped at least 2 months before planned pregnancy)
How to Get Started
- Talk to your doctor – They'll determine if GLP-1 is right for you based on your BMI, health history, and goals
- Check insurance – Coverage varies widely. See our insurance coverage guide for tips
- Start low, go slow – Most meds start at a low dose and increase gradually over several weeks
- Be patient – Full effects take weeks to months. The starting dose is not the therapeutic dose
The Bottom Line
GLP-1 medications work by mimicking a natural hormone that controls appetite, digestion, and blood sugar. They're effective for weight loss and diabetes management, but they're not for everyone. Talk to your doctor about whether they're right for you.
For a complete overview of all available GLP-1 medications, check out our GLP-1 medications explained guide.
This article is for information only and is not medical advice. Always talk to your doctor before starting any medication.