GLP-1 weight-loss medications explained
What are GLP-1 medications?
GLP-1 receptor agonists copy a hormone your gut releases after you eat. They slow how fast your stomach empties and act on appetite centers in the brain, so you feel full sooner and think about food less.
| Drug | Brand for weight loss | Brand for diabetes | How it’s taken |
|---|---|---|---|
| Semaglutide | Wegovy | Ozempic (injection), Rybelsus (pill) | Weekly injection |
| Tirzepatide (GLP-1 + GIP) | Zepbound | Mounjaro | Weekly injection |
| Liraglutide | Saxenda | Victoza | Daily injection |
This guide is educational. Gantsn doesn’t prescribe medication or give doses. Only your doctor can decide what’s right for you.
How much weight do people lose?
In large clinical trials, people taking semaglutide 2.4 mg (Wegovy) lost about 15% of their body weight on average over roughly 68 weeks. People on the highest dose of tirzepatide (Zepbound) lost about 20% over 72 weeks. Results vary a lot from person to person, and those trials also included diet and activity counseling.
Who they’re approved for
In the U.S., the weight-loss versions are generally approved for adults with a BMI of 30 or higher, or 27 or higher with at least one weight-related condition like high blood pressure, type 2 diabetes or high cholesterol. Check your BMI with our BMI calculator.
Common side effects
- Nausea, especially when starting or increasing the dose
- Diarrhea or constipation
- Vomiting, heartburn, burping
- Feeling tired
Doses are usually increased slowly to reduce side effects. More serious risks include gallbladder problems and pancreatitis, and these drugs carry a warning about a type of thyroid tumor seen in animal studies. They aren’t used in people with a personal or family history of medullary thyroid cancer or MEN 2. Your doctor will go over your own risks.
Protect your muscle while on a GLP-1
Because you eat much less, a meaningful part of the weight lost can come from muscle if you’re not careful. Two things help most:
- Eat enough protein: about 0.7–1 g per pound of goal weight a day, even when your appetite is low. See the protein calculator.
- Strength train 2–3 times a week. Try a beginner gym plan or a bodyweight plan.
What happens when you stop?
Many people regain a large share of the weight after stopping, because appetite comes back. Building habits while on the medication (protein at every meal, regular training, daily walking, a food log) gives you the best chance of keeping weight off.
A warning about “research peptides” and unregulated versions
Products sold online as “research chemicals” or “not for human use,” and versions from unverified sellers, may be mislabeled, contaminated or the wrong dose. The FDA has warned about these products. Only use medication prescribed by a licensed clinician and dispensed by a licensed pharmacy.
Questions to ask your doctor
- Am I a good candidate based on my health history?
- Which medication and starting dose would you recommend, and why?
- What side effects should I watch for, and when should I call you?
- How will we protect my muscle and plan for maintenance?
- What will it cost with my insurance, and are there lower-cost options?