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How do Ozempic, Mounjaro, Wegovy, Zepbound compare for weight loss?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Jan 30, 2025.

Official Answer by Drugs.com

Ozempic, Mounjaro, Wegovy and Zepbound can all lead to long-term weight loss, but only Wegovy and Zepbound are approved by the FDA for this use. In studies, Zepbound has led to a 21% weight loss in adults using the highest dose, while Wegovy has led to about a 15% weight loss.

In November 2023, Zepbound, the brand name for Eli Lilly's tirzepatide for weight loss, was approved by the FDA. Wegovy and Zepbound are approved by the FDA for weight loss and chronic weight management, while Mounjaro and Ozempic are both approved for blood sugar (glucose) control in patients with type 2 diabetes.

Both Ozempic and Wegovy are also approved to reduce the risk of cardiovascular death, heart attack and stroke in people with cardiovascular (heart, blood vessel) disease.

In December 2024, Zepbound was approved as the first medicine to treat moderate-to-severe obstructive sleep apnea in adults with obesity.

In January 2025, Ozempic was also approved 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.

Study Overviews

Zepbound (tirzepatide) for chronic weight management (weight reduction and maintenance) was studied in 2 randomized, placebo-controlled, 72-week long, studies (SURMOUNT-1 and SURMOUNT-2) in over 3,400 adults with obesity or excess weight (overweight) and at least one weight-related condition. The primary endpoints of the studies were mean percent change in body weight and the percentage of patients achieving ≥5% weight reduction from baseline to Week 72.

Zepbound: SURMONT-1

Zepbound: SURMONT-2

Wegovy / Ozempic

Wegovy and Ozempic both contain the active ingredient semaglutide, but are approved for different uses.

Although studies evaluating weight loss are available (see below in more detail), it is not possible to fully compare study results for all of these drugs outside of a clinical study as patient populations, doses and study designs differ. There are no studies directly comparing all of these medicines.

What are Ozempic, Mounjaro, Wegovy, and Zepbound approved for?

All of these medications are used in addition to a reduced calorie diet and increased physical activity, as recommended by your doctor. Your individual results may vary.

Selected Weight Loss Studies (in more detail)

Tirzepatide (Mounjaro, Zepbound) has been shown to lead to weight loss when used to treat adults with or without type 2 diabetes.

Mounjaro weight loss in patients with type 2 diabetes

In Phase 3 studies in patients with type 2 diabetes, those treated with Mounjaro lost an average of 5.5 kg (12 lb) to 11 kg (25 lb) over 52-weeks. Mounjaro is approved by the FDA for treatment of type 2 diabetes.

Zepbound weight loss in patients with obesity or overweight

Without type 2 diabetes

Zepbound, approved for chronic weight loss, was evaluated in the SURMONT-1 and SURMONT-2 clinical studies.

The Phase 3 SURMONT-1 study compared weight loss with tirzepatide (Zepbound) to a placebo (inactive) treatment over a 72-week period. Patients did not have a diagnosis of type 2 diabetes.

The study co-endpoints were the percentage change in weight (with the 10 mg and/or 15 mg dose) from the start of the study (baseline) and the percentage of participants with a weight loss of 5% or more at 72 weeks, compared to placebo. At the start of the study, the mean weight of participants was 104.8 kg (230.6 lb) with a mean body mass index (BMI) of 38.

All of the study endpoints were met. Weight loss with all three doses as compared to placebo was statistically significant. At the end of the 72-week study, the mean percent (%) weight loss and average weight loss with tirzepatide (Zepbound) was:

The percentage of patients with a weight loss of 5% or more was 85% to 91% based on dose, compared to 35% with placebo. In addition, 50% to 57% of patients achieved a weight reduction of 20% or more (with the 10 to 15 mg dose) as compared to 3% in the placebo group.

People in the study were able to maintain the weight reduction for the full 72-week study period. At the highest dose, a decrease in waist circumference of 14.5 centimeters (5.7 inches), when adjusted for placebo, was recorded, as well as improvements in blood glucose, cholesterol levels and blood pressure.

The most common side effects were mild-to-moderate nausea, diarrhea and constipation and occurred primarily during the dose escalation period. Treatment discontinuation due to side effects occurred in up to 6.7% of those receiving Zepbound (primary in the first few months due to stomach side effects) and 3.4 % for the placebo group.

With type 2 diabetes

The Phase 3 SURMONT-2 study compared weight loss with tirzepatide (Zepbound) to a placebo (inactive) treatment over a 72-week period. Patients with obesity or overweight did have a diagnosis of type 2 diabetes with an HbA1c of 7% to 10%.

Patients were randomized to receive Zepbound 10 mg, Zepbound 15 mg, or placebo once weekly. Mean body weight at the start of the study was was 100.7 lb (45.8 kg), and enrolled patients also had comorbidities such as high blood pressure, high lipids levels, obstructive sleep apnea, or heart disease.

Weight loss with both Zepbound doses as compared to placebo was statistically significant. Over the 72-week period the mean percent (%) weight loss with tirzepatide (Zepbound) in patients with type 2 diabetes was:

The percentage of patients with a weight loss of 5% or more was 79% to 83% based on dose, compared to 33% with placebo.

Mounjaro vs Ozempic: Weight loss in patients with type 2 diabetes

Approval was based on 5 clinical trials with over 6,200 patients ranging from 40 to 52 weeks. Mounjaro was compared to injectable semaglutide (Ozempic) 1 mg, insulin glargine (Lantus, Toujeo, others) and insulin degludec (Tresiba). Of note, Ozempic is now approved in a higher 2 mg dose, and results vs. Mounjaro may differ with this higher dose.

Efficacy was evaluated for Mounjaro 5 mg, 10 mg and 15 mg used alone or with other commonly prescribed diabetes medications like metformin, SGLT2 inhibitors, sulfonylureas and insulin glargine. Participants achieved average A1C reductions between 1.8% and 2.4%. Weight loss was a secondary outcome in these studies.

While not indicated for weight loss, participants treated with Mounjaro lost between 5.5 kg (12 lb) to 11 kg (25 lb) on average. Weight changes with the comparator agents ranged from a mean weight gain of 1.8 kg (4 lb) to a mean weight loss of 5.9 kg (13 lb).

Related questions

Wegovy: STEP Phase 3 weight loss studies

In the STEP Phase 3 studies, weight loss with Wegovy was assessed up to 68 weeks (104 weeks in STEP 5) in approximately 4,500 adults without type 2 diabetes taking Wegovy or an inactive placebo. STEP 2 did include those with type 2 diabetes. Groups also were counseled to follow a reduced-calorie diet and increased physical activity. The STEP 2 study also compared semaglutide 1 mg to semaglutide 2.4 mg for weight loss. Results from the STEP 1 through 5 studies showed that semaglutide is superior at weight reduction when compared with placebo or the weekly semaglutide 1 mg dose.

Patients were classified as either obese (BMI ≥30) or with excess weight (BMI ≥27) with a weight-related medical problem (such as high blood pressure or high cholesterol).

Wegovy: Weight Loss in Teens

In the Phase 3a STEP TEENS clinical trial with 201 adolescents, participants received either Wegovy or placebo once weekly for 68 weeks in addition to lifestyle interventions.

Common adverse reactions in adolescents included: nausea, diarrhea, vomiting, constipation, abdominal pain, headache, fatigue, and hypoglycemia in patients with type 2 diabetes, among other side effects.

What are the doses?

Mounjaro, Ozempic, Wegovy and Zepbound are all given weekly as a subcutaneous (under the skin) injection in the abdomen, thigh or upper arm. Products are available as injector pens and can be used by the patient or a caregiver at home, after instruction. These medicines should not be used together or with other GLP-1 or GIP / GLP-1 receptor agonists.

How do these drugs work?

Ozempic and Wegovy both contain semaglutide, a GLP-1 (glucagon-like peptide-1) receptor agonist. Semaglutide binds to GLP-1 receptors and stimulates insulin release from the pancreas when needed. It helps with weight loss by slowing down how fast food travels through your digestive tract (called gastric emptying). This may help you to feel fuller for a longer period of time and reduce how much food you consume. Both products are manufactured by Novo Nordisk.

Mounjaro and Zepbound both contain tirzepatide, a dual-acting GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptor agonist. GIP and GLP-1 are both natural incretin hormones. Mounjaro lowers fasting and postprandial (after meals) glucose concentration, decreases food intake, and reduces body weight in patients with type 2 diabetes mellitus. Both products are manufactured by Eli Lilly.

As a group, these medicines are often called "incretin mimetics" because they mimic natural hormones we have in our body, like glucagon-like peptide-1 (GLP-1), which can help you feel fuller.

Selected warnings and side effects

The labeling of these medicines carry a Boxed Warning for possible thyroid tumors, including cancer, which has been seen in animal studies. Do not use Ozempic, Mounjaro, Wegovy or Zepbound if you or anyone in your family has a history of medullary thyroid carcinoma (MTC), or if you have an endocrine system condition called Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Discuss this further with your healthcare provider.

Gastrointestinal (digestive tract) side effects are the most common side effects reported in at least 5% of patients with these medications. Nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion (dyspepsia), and stomach (abdominal) pain have been reported. In some patients, gastrointestinal (digestive system) side effects can be severe enough to lead to treatment discontinuation.

Review the full product information for a complete outline of all side effects, precautions and warnings.

Do Ozempic, Mounjaro, Wegovy, or Zepbound block the intestine?

After these medicines were approved by the FDA, ileus was reported as a possible side effect and updated in the product labels. An ileus (paralytic ileus) is an intestinal blockage that results in the failure of the intestinal contents to pass through the gut, but it doesn't involve a physical blockage. In paralytic ileus, problems with the muscle or nerves found in the intestine interfere with normal muscle contractions.

Anesthesia and incretin mimetics

There have also been concerns about the use of incretin mimetics (GLP-1 type medications) in patients undergoing general anesthesia. These medications can lead to a delay in stomach (gastric) emptying. Any food left in the stomach increases the risk you might vomit while under anesthesia, leading to regurgitation and aspiration into your airways and lungs. This can increase the risk for pneumonia.

The American Society of Anesthesiologists suggest that adults and children on these types of GLP-1 medicines stop taking it prior to surgery. If you have surgery scheduled, be sure your doctor knows if you take one of these medicines at least one week or more before your scheduled surgery.

Bottom Line

Wegovy (semaglutide) and Zepbound (tirzepatide) are incretin mimetics approved by the FDA for chronic (long-term) weight loss and maintenance.

Ozempic (semaglutide) and Mounjaro (tirzepatide) are approved to manage blood glucose control in patients with type 2 diabetes, but significant weight loss may also occur with these products.

Ozempic and Wegovy are both approved to reduce the risk of cardiovascular death, heart attack and stroke in people with cardiovascular (heart, blood vessel) disease.

Zepbound is also approved to treat obstructive sleep apnea in adults with obesity.

All agents are used in addition to a reduced calorie diet and exercise. They are self-administered by subcutaneous (under the skin) pen injection once weekly.

In studies, patients with or without type 2 diabetes have lost weight with semaglutide (brands: Ozempic, Wegovy). Overall, adult patients have seen about a 15% weight loss with Wegovy and a 6% to 7% weight loss with Ozempic. In children 12 years or age and older, a 16.1% decrease in BMI has been observed with Wegovy.

In studies for patients using Zepbound (tirzepatide), a 21% weight-loss (up to 52 lb) using the highest dose (15 mg) was demonstrated in patients without type 2 diabetes. Zepbound was approved by the FDA for use in weight loss on Nov. 8, 2023.

Gastrointestinal side effects like nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion (dyspepsia), and stomach (abdominal) pain can be significant for some patients using incretin mimetics and may lead to treatment discontinuation. Slowly titrating the dose as recommended by the manufacturer may help to reduce stomach side effects.

Other side effects can include injection site reactions, allergic reactions and hair loss.

This is not all the information you need to know about Mounjaro, Ozempic, Wegovy and Zepbound for safe and effective use and does not take the place of your doctor’s directions. Review the full patient medication guide and discuss this information and any questions you have with your doctor or other health care provider.

References
  • Zepbound (tirzepatide) prescribing information. Nov. 2023. Eli Lilly. Indianapolis, IN. Accessed Nov 9, 2023 at  https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/217806s000lbl.pdf
  • Jastreboff AM, Aronne LJ, Ahmad NN, et al; SURMOUNT-1 Investigators. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022 Jul 21;387(3):205-216. doi: 10.1056/NEJMoa2206038. Epub 2022 Jun 4. PMID: 35658024. Accessed Oct. 25, 2022.
  • Wharton S, Calanna S, Davies M, et al. Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg in adults with overweight or obesity, and the relationship between gastrointestinal adverse events and weight loss. Diabetes Obes Metab. 2022 Jan;24(1):94-105. doi: 10.1111/dom.14551. 
  • Kushner RF, Calanna S, Davies M, et al. Semaglutide 2.4 mg for the Treatment of Obesity: Key Elements of the STEP Trials 1 to 5. Obesity (Silver Spring). 2020 Jun;28(6):1050-1061. doi: 10.1002/oby.22794. 
  • Frías JP, Davies MJ, Rosenstock J, et al; SURPASS-2 Investigators. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021 Aug 5;385(6):503-515. doi: 10.1056/NEJMoa2107519. Epub 2021 Jun 25. PMID: 34170647. Accessed Oct. 25, 2022.
  • Lilly Receives U.S. FDA Fast Track Designation for Tirzepatide for the Treatment of Adults with Obesity, or Overweight with Weight-Related Comorbidities. Drugs.com. Accessed Oct. 25, 2022 at https://www.drugs.com/clinical_trials/lilly-receives-u-s-fda-fast-track-designation-tirzepatide-adults-obesity-overweight-weight-related-20439.html
  • Mounjaro (tirzepatide) prescribing information. May 2022. Eli Lilly. Indianapolis, IN. Accessed Oct 25, 2022 at https://uspl.lilly.com/mounjaro/mounjaro.html#pi
  • New analyses of Mounjaro (tirzepatide) injection for the treatment of adults with type 2 diabetes presented at the American Diabetes Association's 82nd Scientific Sessions. Press Release. Eli Lilly and Co. Accessed Oct. 25, 2022 at https://investor.lilly.com/news-releases/news-release-details/new-analyses-mounjarotm-tirzepatide-injection-treatment-adults
  • Tirzepatide (Mounjaro) for Type 2 Diabetes. Medical Letter. Issue 1654. July 11, 2022. Accessed Oct 25, 2022. 
  • New Weight-Loss Drug Looks Good in Trial. June 6, 2022. Drugs.com. Accessed Oct 25, 2022 at https://www.drugs.com/news/new-weight-loss-looks-good-trial-105811.html
  • ADA: Once-Weekly Tirzepatide Yields Lasting Weight Loss in Obesity. June 7, 2022 at https://www.drugs.com/news/ada-once-weekly-tirzepatide-yields-lasting-weight-loss-obesity-105844.html
  • Ozempic prescribing information. Revised 1/2025. Novo Nordisk. Plainsboro, NJ. Accessed Jan 30, 2025 at https://www.novo-pi.com/ozempic.pdf
  • Wegovy (semaglutide) prescribing information. June 2021. NovoNordisk. Plainsboro, NJ. Accessed Oct. 25, 2022 at https://www.novo-pi.com/wegovy.pdf
  • FDA Approves Once-Weekly Wegovy injection for the Treatment of Obesity in Teens Aged 12 Years and Older. Drugs.com. Accessed Jan 17, 2023 at https://www.drugs.com/newdrugs/fda-approves-once-weekly-wegovy-obesity-teens-aged-12-years-older-5949.html
  • Intestinal obstruction. Mayo Clinic. Accessed Sep 28, 2023 at https://www.mayoclinic.org/diseases-conditions/intestinal-obstruction/symptoms-causes/syc-20351460
  • FDA Adds Warning to Ozempic Label About Risk for Blocked Intestines. Drugs.com. Accessed Sep 28, 2023 at https://www.drugs.com/news/fda-adds-warning-ozempic-label-risk-blocked-intestines-115225.html
  • Patients Taking Popular Medications for Diabetes and Weight Loss Should Stop Before Elective Surgery, ASA Suggests. June 28, 2023. American Society of Anesthesiologists. Accessed Sept 19, 2024 at https://www.asahq.org/about-asa/newsroom/news-releases/2023/06/patients-taking-popular-medications-for-diabetes-and-weight-loss-should-stop-before-elective-surgery

Read next

How long does it take for Ozempic to work?

Your blood glucose (sugar) levels should start to fully decline within the first week after you start using Ozempic (semaglutide) at your regular dose. However, the full effect can take 8 weeks or longer, as this is a long-acting medication that is injected only once per week. Continue reading

Wegovy vs Ozempic: Which is Right for You?

Both Wegovy and Ozempic contain semaglutide, but Wegovy is prescribed for long-term weight management while Ozempic is used to control blood sugar levels in type 2 diabetes and help protect kidney function. They both lower the risk for heart-related complications, but they differ in other approved uses, doses, target populations and costs. Continue reading

How many doses are in an Ozempic pen?

Ozempic pens come in 3 sizes. Each pen holds 4 maintenance doses of either 0.5 mg, 1 mg, or 2 mg of medicine given once weekly and will last for one month. Continue reading

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