Metformin for weight loss: Does it work? How does it compare to Ozempic and Mounjaro?

Key Points

• Metformin is FDA-approved for the treatment of type 2 diabetes, not for weight loss
• Typical weight loss with metformin is about 2% to 5% of body weight
• Metformin helps the body use insulin better and lowers the amount of sugar released by the liver, so weight changes tend to be modest and gradual

Diabetes weight loss drugs have been getting a lot of attention lately.

Much of the focus is on newer medications like Mounjaro and Ozempic, which have been linked to dramatic weight loss.

Metformin, however, is still commonly prescribed for type 2 diabetes. So, it’s natural to wonder: 

Does metformin help with weight loss? Or is its role limited to blood sugar control?

Here’s what’s known about metformin and weight loss, including whether it’s approved for weight loss and how it compares with Ozempic and Mounjaro.

What is metformin? How does it work?

Metformin is an oral medication approved by the FDA in 1994 for the treatment of type 2 diabetes.

It works by:

• Reducing the amount of glucose released by the liver into the bloodstream
• Improving how efficiently muscle and fat cells respond to insulin
• Modestly affecting glucose absorption in the digestive tract

Together, these actions help lower blood glucose levels.

Most people lose little or no weight on metformin. 

Can metformin be used for weight loss?

Metformin is approved to treat type 2 diabetes in adults and children aged 10 years and older. It is not FDA-approved for weight loss.

When weight loss happens, it is considered a secondary effect, not the main goal of treatment.

How much weight can you lose on metformin?

Most people lose little or no weight on metformin. When weight loss does happen, it is usually modest.

On average, weight loss on metformin is about 2% to 5% of the starting body weight. For someone who weighs 200 pounds, a 2% to 5% weight loss is roughly 4 to 10 pounds.

This data comes from the Diabetes Prevention Program (DPP), a large, long-term study of more than 3,200 adults at high risk for type 2 diabetes. It tracked weight changes over time in people taking metformin, not just short-term results.

Metformin vs. Mounjaro (tirzepatide)

Metformin and Mounjaro are medications used to treat type 2 diabetes. Both these drugs are not approved for weight loss.

However, weight loss has been reported in studies.

Weight loss results

In general, people in studies lost more weight on Mounjaro than metformin:

• Mounjaro: about 15%–20% body weight loss
• Metformin: about 2%–5% body weight loss

The difference seen with Mounjaro vs. metformin comes from how the medications are designed to work in the body.

Why the results differ

Mounjaro helps the pancreas release insulin when blood sugar rises, while also reducing hunger and slowing digestion, which can lead to greater weight loss.

Metformin helps the body respond better to insulin and reduces the amount of sugar released by the liver. So, its effects on weight tend to be smaller.

How they are administered

Mounjaro is a once-weekly injection. It is available in several dose levels that are adjusted over time.

Metformin is taken as a pill, usually once or twice daily depending on the formulation. It comes in immediate-release and extended-release forms.

Metformin vs. Ozempic (semaglutide)

Metformin and Ozempic are both used to treat type 2 diabetes. Neither is approved as a weight loss drug in the United States.

Weight loss results

In studies, people taking Ozempic generally lost more weight than those taking metformin:

• Ozempic: about 10%–15% body weight loss
• Metformin: about 2%–5% body weight loss

The differences between Ozempic vs. metformin reflect how the medications are designed to work in the body.

Why the results differ

Ozempic lowers blood sugar, reduces hunger, and slows digestion, which helps explain the greater weight loss observed (compared to metformin).

Metformin focuses on improving insulin response and limiting sugar release from the liver, so its effects on weight are more modest.

How they are administered

Ozempic is a once-weekly injection available in various doses. Metformin is a pill taken once or twice a day.

Note: Mounjaro, Ozempic, and metformin are prescription medications that must be prescribed by a licensed healthcare provider.

Does insurance cover metformin for weight loss?

When prescribed for type 2 diabetes, metformin is commonly covered by private insurers, Medicare Part D, Medicaid, and many commercial insurance plans.

Note:

• Coverage varies by insurance plan, so please check directly with your provider
• Off-label metformin use for weight loss has limited or no insurance coverage

Final thoughts: Metformin for weight loss

Metformin is a long-standing treatment for type 2 diabetes. It is widely used and affordable.

In the United States, metformin is not approved as a weight loss drug. When weight loss occurs, it is usually modest and varies from person to person.

Overall, the evidence shows that metformin’s role in weight change is limited. Larger and more consistent weight loss is more often seen with medications developed specifically for weight management.

Lose weight with a personalized diabetes diet plan from a registered dietitian, covered by insurance.

Frequently Asked Questions (FAQs)

How to lose weight fast on metformin?

Metformin is not approved as a weight loss drug and is approved only to treat type 2 diabetes. Metformin is not designed for rapid weight loss. In studies, weight loss on metformin is usually modest and gradual (2%-5% of starting body weight).

Is metformin FDA-approved for weight loss?

No. Metformin is not FDA-approved for weight loss. It is approved only to treat type 2 diabetes in adults and children aged 10 years and older.

Is metformin cheaper than Zepbound?

Yes. Metformin is available as a generic and typically costs far less than the cost of Zepbound. However, what people actually end up paying can vary depending on insurance coverage and the manufacturer’s Zepbound savings programs.

💡Bonus section

Can metformin help with PCOS?

Metformin is not approved to treat polycystic ovary syndrome (PCOS) in the United States. It is approved only for type 2 diabetes.

However, PCOS is often linked to insulin resistance and weight gain from higher levels of male sex hormones (androgens). Research suggests that even modest weight loss can help improve PCO symptoms. Even a 5% to 10% weight loss can help.

In a long-term study, women with PCOS and obesity who took metformin saw modest decreases in BMI and more regular menstrual cycles.

Lose weight on metformin the healthy way. Find a weight loss dietitian who accepts your insurance.

The views expressed by authors and contributors of such content are not endorsed or approved by Fay and are intended for informational purposes only. The content is reviewed by Fay only to confirm educational value and audience interest. You are encouraged to discuss any questions that you may have about your health with a healthcare provider.