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Metformin vs Ozempic for weight loss — which is better?

Written by Patricia Weiser, PharmD

Published: Jun 10, 2024

Medically Reviewed by Goldina Erowele, PharmD, MBA

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Losing weight and keeping it off can be a difficult task. Lifestyle changes help, but sometimes diet and exercise aren’t enough to achieve your weight loss goals. That’s why many people turn to weight loss medications. But with so many options available, it’s challenging to find the right one. 

Two medications initially designed to treat type 2 diabetes — metformin and Ozempic (semaglutide) — are proven to help people lose weight. In this article, we compare metformin vs Ozempic for weight loss to help you determine if either is a good choice for you.

If you’re considering options like Ozempic or metformin for weight loss, don’t wait to consult a healthcare provider. Book an appointment with a provider on Klarity today to discuss your weight loss goals.

Get a prescription for Ozempic, metformin, or another weight loss medication online in as little as 24 hours.

Metformin vs Ozempic: which helps you lose more weight?

No clinical trials directly compare metformin vs Ozempic for weight loss, but data from separate studies lets us see which causes more weight loss. Based on these results, Ozempic helps more people lose weight successfully and achieve greater weight loss than metformin. 

Providers frequently prescribe Ozempic for weight loss for people without type 2 diabetes, this is an off-label use and isn’t a common practice with metformin. Yet, some clinical reviews suggest combining these medications could result in greater weight loss. Let’s examine the study data to understand the weight loss potential of each medication and the possible benefits of taking metformin and Ozempic together.

Weight loss with metformin

Metformin is a first-line medication for controlling blood glucose (sugar) levels in people with type 2 diabetes. It can help some people lose some weight as an extra benefit, but weight loss isn’t consistent. Because many metformin studies look at diabetes outcomes, it’s tricky to predict how much weight someone will lose, if any, while taking metformin. 

The clinical trials used to support the US Food and Drug Administration (FDA) approval of metformin included nearly 1,000 individuals with type 2 diabetes. Those taking the medication lost an average of 8.4 pounds over 29 weeks, compared to no weight loss for people taking a placebo. 

Other studies of metformin’s role in weight loss produced conflicting results. In 1 study of more than 5,000 people with diabetes, metformin appeared “weight-neutral” when compared to other diabetes medications. This means no significant weight loss or gain was identified. Another study of 4,000 participants found that taking metformin led to an average weight loss of about 6 pounds, while those taking other diabetes medications gained weight.

A large clinical trial, known as the Diabetes Prevention Program, highlights metformin’s potential effectiveness for weight loss. The program enrolled 3,200 individuals with prediabetes and obesity. It compared weight loss in participants taking metformin over 15 years to those only making diet and exercise changes. After 1 year, more than 25% of those taking metformin lost at least 5% of their initial body weight, compared to only 13% of those taking placebo. Those in the metformin group were also more likely to keep the weight off. More than 6% of the metformin group remained at their reduced (end of study) body weight long-term, while about 3% of the placebo group managed to do the same.    

Weight loss with Ozempic 

Ozempic’s weight loss potential was revealed during the clinical trials designed to support the medication’s FDA approval for type 2 diabetes. The SUSTAIN trials for Ozempic enrolled more than 8,000 people with type 2 diabetes and obesity. The main focus was to demonstrate Ozempic’s safety and effectiveness for managing type 2 diabetes. Across the 5 SUSTAIN trials, participants taking Ozempic lost an average of 10 to 15 pounds over 56 weeks. Nearly 65% of the Ozempic group lost at least 5% of their starting weight, and more than 25% lost at least 10% body weight. 

After seeing Ozempic’s potential for weight loss, its manufacturer, Novo Nordisk, started a new clinical trial program focused solely on assessing safety and efficacy for weight loss. The STEP2 trial compared Ozempic to placebo in 1,200 individuals with type 2 diabetes and obesity. Those taking the medication, alongside diet and exercise, lost an average of 9.6% of their body weight. Over 25% of participants taking Ozempic achieved weight loss of 15% or more, and 13% lost over 20% of their baseline weight.

Weight loss with Ozempic and Metformin together

Healthcare providers frequently prescribe Ozempic in addition to metformin to help lower blood sugar levels and/or support weight loss. Metformin and Ozempic are safe to take together. They both lower blood sugar levels and help with weight loss, but work in different ways. Some people even experience better results with the combination than with either medication alone. 

While studies of this combination are limited, a collective review of smaller clinical trials found that adding Ozempic after achieving weight loss with metformin causes an additional 4 to 6% reduction from starting body weight. This suggests that, together, these 2 medications lead to even more weight loss.

The American Diabetes Association (ADA) recommends weight loss as an important strategy for managing type 2 diabetes, along with a healthy diet and exercise. Based on available scientific evidence, the experts at ADA suggest medications like semaglutide (Ozempic) or tirzepatide (Mounjaro) for people with type 2 diabetes and obesity. These medications are proven to help with weight loss and improve blood sugar levels. They also offer benefits for cardiovascular health.

How do Metformin and Ozempic work for weight loss?

Metformin belongs to a class of medications known as biguanides. It helps lower blood sugar by increasing the body’s sensitivity to insulin and altering the way the body breaks down sugar. Metformin’s mechanism for weight loss is less clear, but likely works in a number of ways. Studies suggest that it’s associated with mild appetite suppression and changes to how the stomach and intestines break down food.

Ozempic belongs to a class of drugs known as glucagon-like peptide 1 (GLP-1) agonists. It enhances the effects of the natural GLP-1 hormone to encourage more insulin production and lower blood sugar levels. GLP-1 works for weight loss by slowing the rate at which the stomach digests food, keeping you feeling fuller for longer. When you’re not as hungry, you tend to eat less and weight loss follows.

How else are Metformin and Ozempic different and similar?

Metformin and Ozempic have many similarities, but there are key differences in their FDA-approved uses, dosage forms, and how you take them. Understanding these differences can help when asking your doctor for weight loss medication

Metformin vs Ozempic: FDA-approved uses

The FDA approves medications for specific uses based on clinical trial data that demonstrate their effectiveness and safety. Drug indications (approved uses) are listed on the medication’s labeling (prescribing information or PI). The FDA approves metformin and Ozempic for similar, but slightly different, indications.

Metformin was FDA-approved in 1995 to help control blood sugar levels in adults and children aged 10 years and older with type 2 diabetes, along with diet and exercise.

Ozempic has 2 FDA-approved uses:

  • To improve blood sugar control in adults with type 2 diabetes, alongside diet and exercise.
  • To lower the risk of a major cardiovascular event, such as heart attack or stroke, in adults with both type 2 diabetes and heart disease.

Healthcare providers can prescribe medications for a purpose outside the approved indications on the drug’s labeling. This is called off-label prescribing. Providers commonly prescribe Ozempic off-label for weight loss. They may choose to prescribe Wegovy vs Ozempic. Wegovy is a brand-name version of semaglutide that’s FDA-approved for weight loss in certain people with overweight or obesity.  

Metformin vs Ozempic: forms and dosages

One of the major differences between metformin and Ozempic is how you take them.

Metformin comes as a tablet, extended-release tablet, and liquid solution, all of which are taken by mouth. Metformin comes in multiple strengths ranging from 500 to 1,000 milligrams. Most people take metformin once or twice daily, depending on the specific form of metformin you take. 

Ozempic is an injection that comes in a single-use, prefilled injection pen. Ozempic pens are available in various strengths that provide 0.25, 0.5, 1, or 2 milligrams per injection. You inject Ozempic directly below the skin (subcutaneously) into the abdomen, thigh, or back of the upper arm. Unlike metformin, you only take Ozempic once a week. 

Due to national drug shortages, it can be difficult to find Ozempic in stock. Metformin may be easier to get. Another Ozempic alternative to consider is compounded semaglutide. Compounding pharmacies offer custom-made medications, with a prescription from a licensed healthcare provider. When choosing a compounding pharmacy, make sure they’re licensed by the FDA.

The table below compares some key similarities and differences between metformin and Ozempic. 

MetforminOzempic
Drug classBiguanidesGLP-1 receptor agonists
Active ingredientMetforminSemaglutide
Brand nameGlucophage, Fortamet, Glumetza, and others Ozempic
Generic availability?YesNo
FDA-approved usesImproved blood sugar control in adults and children ages 10+ with type 2 diabetesImproved blood sugar control and lower risk of a cardiovascular event in adults with type 2 diabetes, along with diet and exercise
Common off-label usesPolycystic ovary syndrome (PCOS), weight lossWeight loss
Potential weight lossBetween 2 – 4% of baseline body weight over 52 weeksBetween 5 – 10% of baseline body weight over 56 weeks
Dosage forms and strengthsTablet:
500 mg, 850 mg, 1000 mg
Extended-release tablet:
500 mg, 750 mg, 1000 mg
Oral solution:
500 mg per 5 mL
Injectable solution in an injector pen that delivers 0.25 mg, 0.5 mg, 1 mg, or 2 mg per injection
Cost per month*Averages $10 to $15 per monthUp to $1,029 per month
Common side effectsDiarrhea, gas, headache, indigestion, nausea, weaknessAbdominal pain, constipation, diarrhea, nausea, vomiting
*Prices according to drugs.com with their discount card, at the time of publication

Metformin or Ozempic: which costs less?

Another major difference between metformin and Ozempic is how much they cost.

Metformin is available as an inexpensive generic drug, while Ozempic isn’t. Depending on the form and strength of metformin, a 1-month supply averages $10 to $15, sometimes less. Ozempic pens cost more — a 1-month supply retails for $1,029. These prices are according to drugs.com with their discount card.

You may qualify for savings with the Ozempic Savings Card. Offered by the manufacturer, Novo Nordisk, the savings card lets qualifying individuals with commercial insurance to get Ozempic for as little as $25 a month for 2 years. They also offer a Patient Assistance Program for those uninsured or underinsured. Talk to a pharmacist or visit the Ozempic website to learn more about eligibility and next steps.

Metformin vs Ozempic: how does insurance coverage compare?

Insurance plans almost always cover metformin, and they typically don’t require documentation confirming if it’s being used for diabetes or another purpose, such as weight loss. 

You’re likely to get Ozempic covered by insurance if you have type 2 diabetes. It’s less likely to be covered for weight loss if you don’t have type 2 diabetes. 

Before insurance plans cover Ozempic, they may require prior authorization (PA). The PA process requires additional paperwork from your healthcare provider documenting the reason Ozempic is medically necessary for you. Reach out to your insurance company for their Ozempic prior authorization criteria and to check the status of your PA request. 

Because Ozempic is expensive, some insurance providers will deny PA because they want you to try less expensive options first — a technique known as step therapy. To qualify for Ozempic, have your prescriber provide your diagnosis and list the medications you’ve already tried, such as metformin or another weight loss medication.

Metformin vs Ozempic: how do side effects compare?

Despite working in different ways, metformin and Ozempic cause similar side effects — most digestion-related. For both medications, digestion-related side effects are typically worse when starting the drug or after you increase your dose. These side effects typically become less frequent and severe as treatment continues. Metformin generally takes less time for your body to adjust to than Ozempic.

Metformin side effects

Metformin commonly causes mild side effects, such as:

  • Diarrhea
  • Nausea or vomiting
  • Gas
  • Weakness
  • Indigestion
  • Abdominal discomfort
  • Headache

In rare cases, metformin causes serious side effects, including lactic acidosis, vitamin B–12 deficiency, and allergic reactions. Hypoglycemia (dangerously low blood sugar levels) is possible if you’re taking metformin with insulin or another medication to lower your blood sugar. If you experience severe side effects, contact your healthcare provider or dial 911.

Ozempic side effects

Common side effects of Ozempic are usually mild and include:

  • Nausea
  • Vomiting
  • Diarrhea
  • Constipation
  • Abdominal Pain

Sometimes, taking Ozempic causes serious side effects. These include allergic reactions, gallbladder problems, pancreatitis, kidney problems, or low blood sugar. If you experience severe side effects, contact your healthcare provider or dial 911.

How to decide whether to take Metformin vs Ozempic for weight loss

Determining which weight loss medication is right for you, if any, is a personal decision that depends on several factors. These include cost, preference (such as oral vs injectable semaglutide), side effects, insurance coverage, and drug availability. Share your medical history and work closely with your healthcare provider to make the safest and most effective choice.

Key takeaways

Losing weight and keeping it off can be difficult, and lifestyle changes alone aren’t always enough. Metformin and Ozempic are commonly prescribed off-label for weight loss. Both medications were originally designed to help control blood sugar levels in people with type 2 diabetes. 

Ozempic works better than metformin for weight loss. Clinical trials for Ozempic display significant weight loss, but metformin’s impact is inconsistent. Some studies show modest weight loss with metformin while others show it as “weight-neutral.” Taking both medications together can lead to additional weight loss, according to research.

When comparing Metformin vs Ozempic for weight loss, there are other differences and similarities to consider, like:

  • Metformin is taken by mouth once or twice a day, while Ozempic is given once a week as a subcutaneous weight loss injection
  • Metformin is a cheap generic medication — a 30-day supply costs as low as $10 without insurance. Ozempic is an expensive brand-name medication that retails for $1,029 per month. If you get Ozempic with insurance coverage or various cost assistance programs, you may pay less if you’re eligible. 
  • Metformin’s common side effects include diarrhea, nausea, and abdominal discomfort, while Ozempic commonly causes nausea, vomiting, and constipation. Serious side effects for each medication are rare but possible.

Find a provider on Klarity and get the right weight loss med for you

Klarity helps you find a provider specialized in weight management. Book an appointment with a provider on Klarity today to learn about your options and start your weight loss journey.

FAQ: Metformin vs Ozempic for weight loss

Is Ozempic more effective than metformin for weight loss?

Individual clinical trial results for Ozempic and metformin show that Ozempic helps more people lose more weight than metformin. Both medications offer some weight loss when paired with a healthy diet and increased exercise.

What is the average weight loss with metformin?

It depends. When paired with diet and exercise, the largest metformin study in adults with type 2 diabetes found that the average person lost between 2% and 4% of their initial body weight over 1 year. Over 25% of individuals lost at least 5% of their body weight.

What works better than Ozempic for weight loss? 

Wegovy (semaglutide) is another GLP-1 receptor agonist with the same active ingredient as Ozempic. It’s FDA-approved specifically for weight loss in certain adults and children who qualify as overweight or obese. A newer medication, Zepbound (tirzepatide), is even more effective for weight loss than semaglutide. As with most medications, individual results vary.

What is the downside of taking metformin?

As with any medication, metformin may cause side effects. Typically, these affect the digestive tract. The most common side effect is diarrhea, followed by nausea, gas, and abdominal discomfort. Metformin side effects usually ease within a few days or weeks as your body adjusts to the medication. 

How can I get Ozempic for $25?

Depending on your insurance coverage, you may be eligible to get Ozempic for $25 per month through a manufacturer program. Talk to a pharmacist or visit the Ozempic website to learn more.

Sources

American Diabetes Association, Obesity and weight management for the prevention and treatment of type 2 diabetes, Dec. 2023, https://diabetesjournals.org/care/article/47/Supplement_1/S145/153942/8-Obesity-and-Weight-Management-for-the-Prevention

Annals of Medicine, Comparative efficacy and safety profile of once-weekly semaglutide versus once-daily sitagliptin as an add-on to metformin in patients with type 2 diabetes: a systematic review and meta-analysis, Aug. 2023, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10375936/

Annals of Internal Medicine, Long-term weight loss with metformin or lifestyle intervention in the diabetes prevention program outcomes study, May 2021, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6829283/

Current Obesity Reports, Metformin: mechanisms in human obesity and weight loss, Jun. 2019, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520185/

DailyMed, Metformin hydrochloride tablet, Apr. 2021, https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=8cd5555c-f6b2-28d8-e053-2a95a90a5f1e&type=display

DailyMed, Metformin hydrochloride tablet, extended release, Jun. 2020, https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=d01b63e6-70e5-4679-b377-1e0fb78a87b5&type=display

DailyMed, Ozempic (semaglutide) injection, solution, Sept. 2023, https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=adec4fd2-6858-4c99-91d4-531f5f2a2d79&type=display

Diabetes, Obesity, & Metabolism, Semaglutide induces weight loss in subjects with type 2 diabetes regardless of baseline BMI or gastrointestinal adverse events in the SUSTAIN 1 to 5 trials, Sept. 2018, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6099440/

Drugs.com, Metformin price guide, https://www.drugs.com/price-guide/metformin

Drugs.com, Ozempic price guide, https://www.drugs.com/price-guide/ozempic

The Lancet, Semaglutide 2.4mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2): a randomised, double-blind, double-dummy, placebo-controlled, phase 3 trial, Mar. 2021, https://www.sciencedirect.com/science/article/pii/S0140673621002130

U.S. Food and Drug Administration, Orange book: approved drug products with therapeutic equivalence evaluations, https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

The information provided in this article is for educational purposes only and should not be construed as medical advice. Always seek the guidance of a qualified healthcare professional with any questions or concerns you have regarding your health.

How we reviewed this article: This article goes through rigorous fact-checking by a team of medical reviewers. Reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the author.

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