Doctors typically prescribe metformin for people with diabetes or prediabetes to help manage the condition. People who take the medication may experience weight loss.

Metformin is an FDA-approved drug prescribed for managing blood sugar levels in people with type 2 diabetes.

Some research suggests it may lead to weight loss, but there may be some risks to consider.

Here’s what you should know about what metformin can do for weight loss, as well as why a doctor or another healthcare professional may prescribe it for you.

The FDA has not approved metformin as a stand-alone weight loss drug.

However, people using metformin for its FDA-approved use may lose weight as a side effect. The exact mechanism of why weight loss may occur is unclear. Unlike other diabetes medications, metformin does not cause weight gain.

Appetite reduction

One theory is that metformin reduces your appetite, prompting you to eat less.

The methods by which metformin affects appetite aren’t clear but may include:

  • interfering with gut microbiota
  • prompting the release of appetite-suppressing hormones
  • affecting appetite-regulating parts of the brain

Metformin may also lead to diarrhea, bloating, and nausea, which may reduce how much you wish to eat.

Long-term weight loss

A long-term study involving people with diabetes assessed weight loss over 15 years.

Researchers found that for people who lost more than 5% of body weight in the first year, those taking metformin had greater success with maintaining weight loss in years 6 to 15.

However, it’s important to note that taking metformin without following other health-promoting habits, such as eating a diet rich in whole foods and staying physically active, may not lead to weight loss.

Any weight loss you experience may only last as long as you take the medication. That means if you stop taking metformin, there’s a good chance you’ll return to your original weight. And even while taking the drug, you may slowly gain back any weight you’ve lost.

If you have type 2 diabetes or prediabetes and also have overweight or obesity, a doctor may prescribe metformin to help you manage your diabetes or lower your risk of developing it.

However, some research suggests a doctor might prescribe metformin for weight loss even if you do not have diabetes or prediabetes. This is an off-label use.

Off-label means the FDA has not approved a drug for the specific use, which in this instance is as a weight loss aid. As a result, there’s less information about its effectiveness for this purpose.

Metformin is a diabetes medication. There are no official dose recommendations for it as a weight loss aid.

If a doctor prescribes taking metformin for an off-label use, they’ll decide on a dose that’s right for you and your medical circumstances. You’ll likely start metformin at a low dose and gradually increase it over a few weeks. This can help minimize any side effects.

One off-label use of metformin is for antipsychotic, drug-induced weight loss. Doses for immediate-release metformin can range from 750 to 2,000 milligrams (mg). Extended-release doses may range from 500 to 2,000 mg.

Although metformin has been shown to promote weight loss when used off-label, it may also cause side effects.

The most common side effects of metformin include:

These side effects will typically get better after taking metformin for some time. However, a 2020 review indicated that taking metformin also leads to other side effects, such as:

The authors concluded that taking metformin off-label for weight loss may not be safe because more research is needed to determine the long-term side effects.

Learn more about the side effects of metformin.

Metformin is a relatively safe drug with side effects that usually go away over time. Any weight loss you may experience while taking it should be gradual and minimal and not cause alarm.

That said, speak with a doctor if you’re concerned about the amount of weight you lost while taking metformin. They may suggest modifying your diabetes treatment plan. They can also help determine the underlying cause of weight loss.

How quickly can you lose weight on metformin?

A 2019 review found that metformin may cause weight loss in as little as 1 month.

Can a person without diabetes take metformin for weight loss?

The 2019 review highlighted above also suggests metformin may lead to weight loss in a person without diabetes. However, it’s important to note the FDA has not approved the use of metformin for weight loss. As such, this is considered an off-label drug use.

Which is better for weight loss, Ozempic or metformin?

Ozempic and metformin are both diabetes medications that may also lead to weight loss.

The road to weight loss may vary from person to person, but eating a balanced diet and staying physically active, such as regularly exercising, play key roles in maintaining a health-supporting, sustainable weight loss regimen.

Talk with a doctor to learn more about metformin and weight loss. They can answer your questions and help you find a weight loss plan that’s right for you. Some questions you might ask include:

  • Can you recommend a diet and exercise program to help me lose weight?
  • What’s a reasonable weight loss goal for me?
  • Should I work with a dietitian to help with my diet?
  • Do I need medication to help me lose weight?
  • If I lose weight, could I stop taking some medications for diabetes, high cholesterol, or high blood pressure?