There are currently two GLP-1 agonists and one dual GIP/GLP-1 agonist approved to treat obesity.
The FDA has approved the following for weight loss in people with obesity:
GLP-1 Agonists
- liraglutide (Saxenda)
- semaglutide (Wegovy)
GIP/GLP-1 Agonist
- tirzepatide (Zepbound)
Millions of Americans are now using GLP-1 and GIP/GLP-1 agonist medications. Roughly 12 percent of adults in the United States have tried a GLP-1 drug, and 6 percent are currently using one, according to a poll.
Beyond helping with weight management, these medications also improve metabolic health more broadly, lowering blood pressure, blood sugar, cholesterol, and inflammation. Early research suggests they may also reduce cravings and addictive behaviors — and even provide cognitive protection against Alzheimer’s disease and dementia.
Most GLP-1 and dual GIP/GLP-1 agonists are injected.
The three FDA-approved medications for weight loss are injected daily or weekly:
- liraglutide (GLP-1): once a day
- semaglutide (GLP-1): once a week
- tirzepatide (dual GIP/GLP-1): once a week
These injectable medications come in prefilled pens. Depending on which medication you’re on, either you’ll attach a needle to the pen, prick yourself in the abdomen, thigh, or upper arm, and press the button on the pen to administer the shot, or you’ll use an auto-injector, which has the needle already spring-loaded in the pen, but the other steps are the same. Doctors usually prescribe a lower dose to start with and work up to a full-strength dose over several months to minimize side effects.
Rybelsus, another semaglutide, is taken orally, once a day. It’s approved for type 2 diabetes by the FDA, but some doctors may prescribe it off label for obesity.
Once you start the medication, you may notice a decreased appetite and increased satiety within a few days or weeks. Weight loss usually takes longer, often starting after about four months. How quickly the medication works is based on several factors, such as diet, exercise routine, metabolism, stress levels, and more.
Most people on a GLP-1 or dual GIP/GLP-1 agonist hit a weight loss plateau at a certain point, which varies by medication. For example, some research shows that people on liraglutide hit a plateau after 20 weeks of taking the medication, while those on tirzepatide hit a plateau after 72 weeks. When weight will begin to level off for you depends on factors such as metabolism and the dose and type of medication you’re taking.
GLP-1 agonists and dual GIP/GLP-1 agonists quiet food noise.
After starting one of these medications, people who constantly think about what to eat next often report feeling like a “switch just gets turned off,” says Dr. Saleh. GLP-1s help with this food noise in multiple ways. “One, they slow stomach emptying, so people feel full faster and satisfied longer, which reduces the desire to eat,” she says. “Two, they suppress cravings for highly palatable foods — those high in fat and sugar.”
GLP-1 agonists and dual GIP/GLP-1 agonists come with side effects, but they’re usually temporary.
The most common side effects are acid reflux, constipation, fatigue, headaches, indigestion, mild nausea, and vomiting, which Saleh says “are often eliminated or lessened as the medication stays in the body and you shift your lifestyle and eating habits.” To minimize these side effects, avoid foods that are spicy or high in fat, and eat smaller, more frequent meals.
Other, rare side effects associated with taking these drugs include gallstones, pancreatitis, and more severe gastrointestinal problems, such as bowel obstruction or gastroparesis (in which the muscles in the stomach are partially paralyzed and don’t move properly for digestion). GLP-1s are not recommended for people who have a personal or family history of a rare genetic form of thyroid cancer called medullary thyroid cancer (MTC) or a genetic syndrome called multiple endocrine neoplasia type 2 (MEN2).
GLP-1 agonists and dual GIP/GLP-1 agonists work best alongside a healthy lifestyle.
The FDA notes that these medications should not be used alone but in addition to a reduced-calorie diet and increased physical activity. Proper sleep and stress management also play a role in the ability to lose weight. “The key is that success isn’t just about the number on the scale. It’s about feeling good about yourself, getting healthier for yourself and for your family, and making sure you’re doing it in a healthy way,” says Saleh.
Self-Reflection
Before you meet with your doctor, ask yourself these questions:
- What do I hope to get out of this treatment beyond weight loss?
- Am I comfortable injecting myself with a pen once a week or once a day? If not, what would help me feel more confident?
- How much time can I realistically commit to making healthy lifestyle changes?
- Do I have a support system in place to help motivate me to maintain lifestyle changes?
- What is my insurance situation? Will the medication be covered? If not, can I afford to pay for it out of pocket?
- Do I have family planning goals (for example, breastfeeding, pregnancy, or trying to conceive in the next year)?
- What are my biggest concerns about the side effects or long-term use?
Doctor Discussion
Bring this list of questions to your next appointment to guide the conversation:
- Am I a candidate for a GLP-1 or dual GIP/GLP-1 agonist, considering my personal and family medical history?
- How do you decide which medication is best for me?
- Do I have other obesity-related health conditions that this treatment might help?
- How often will I need to take the medicine?
- What kind of weight loss or health improvements should I realistically expect, and how soon might I see results?
- Are there any behavioral or psychological factors that could have an impact on the effectiveness of these drugs?
- What side effects or complications should I monitor myself for while taking these medications?
- How often will I need follow-up visits, lab work, or other tests?
- What changes should I make to my eating, exercise, and daily habits to help the medicine work better?
- What’s the long-term plan? Will I need to stay on this medicine indefinitely?
- If the medicine doesn’t work for me or my insurance doesn’t cover it, what other options do I have?
Adam Gilden, MD, MSCE
Medical Reviewer
Adam Gilden, MD, MSCE, is an associate director of the Obesity Medicine Fellowship at University of Colorado School of Medicine and associate director of the Colorado University Medicine Weight Management and Wellness Clinic in Aurora. Dr. Gilden works in a multidisciplinary academic center with other physicians, nurse practitioners, registered dietitians, and a psychologist, and collaborates closely with bariatric surgeons.
Gilden is very involved in education in obesity medicine, lecturing in one of the obesity medicine board review courses and serving as the lead author on the Annals of Internal Medicine article "In the Clinic" on obesity.
He lives in Denver, where he enjoys spending time with family, and playing tennis.
Susan Jara
Author
Susan Jara is a health communications strategist and writer with more than 15 years of experience transforming complex medical information into clear, accurate, and engaging content for diverse audiences of patients and caregivers. She specializes in patient education, health literacy, and SEO-driven content strategy, with expertise across chronic disease, mental health, addiction, arthritis, autoimmune conditions, and wellness.
Susan holds a bachelor’s degree in journalism and media studies from New York University’s Gallatin School of Individualized Study. Her career includes leadership roles at the Global Healthy Living Foundation and Health Monitor Network, where she developed multichannel health content across web, email, podcasts, video, social media, and print. Susan's work reaches millions of readers each year, and she collaborates with leading healthcare providers, researchers, advocacy groups, and industry partners to create resources that reach millions of readers each year.