Metformin For Weight Loss: Does It Work?

Craig Primack, MD, FACP, FAAP, FOMA

Reviewed by Craig Primack, MD, FACP, FAAP, FOMA

Written by Rachel Sacks

Published 10/23/2024

When it comes to weight loss, there are a number of tried and true lifestyle changes you can make to help you along the way. But sometimes, those extra pounds are as stubborn as a toddler who doesn’t want to go to bed.

We all know the dangers associated with carrying excess weight, and given that the obesity prevalence among adults was nearly 42 percent from 2017 to 2020, it’s no surprise that weight loss drugs like Wegovy® and Ozempic® have become increasingly popular.

You may have also heard that metformin, a diabetes drug for managing blood sugar levels, can help you lose weight. But is it true?

Below, we’ll answer the question of whether metformin can cause weight loss and explain how this drug works.

Metformin is an FDA-approved medication for people with type 2 diabetes mellitus, a common condition in which the body doesn’t produce enough insulin.

Off-label, metformin is also used to manage gestational diabetes (a type of diabetes that develops during pregnancy) and treat polycystic ovary syndrome (PCOS). It’s also the only diabetes medication recommended for prediabetes by the American Diabetes Association (ADA).

Exactly how it works isn’t quite clear but researchers believe the medication causes your liver to lower the amount of glucose it makes and releases into your bloodstream.

In other words, metformin helps your body respond better to the insulin it makes and decreases the amount of glucose that your intestines absorb. This helps keep your blood glucose levels (or blood sugar levels) in a healthy range, which can help prevent serious health issues like heart disease and loss of vision.

Metformin can cause side effects, like any medication. Common side effects of metformin include diarrhea, nausea and vomiting.

Although less common, some people may have chest discomfort, headaches, sweating, hypoglycemia (low blood sugar) and weakness. 

An even less frequent, yet severe, side effect of metformin is lactic acidosis, or a buildup of lactic acid in the blood. This happens when there’s not enough oxygen in the muscles to break down glucose.

But back to the question that’s probably on your mind right now: can metformin cause weight loss? The short answer seems to be yes: people using this medication may experience a reduction in body fat.

When metformin was tested in a large study on patients with diabetes, the researchers also noticed a significant decrease in weight and waist measurements.

In this study — the Diabetes Prevention Program Outcomes Study from 1996 to 1999, to be specific — patients took either metformin or a placebo.

Not only did metformin reduce diabetes by 31 percent over three years, but follow-up studies found that those taking the drug also lost 3.8 kg (or 8.4 pounds) after 29 weeks of treatment and had reductions in waist circumference.

A more recent 2020 meta-analysis of 21 trials testing metformin found the drug had a modest effect on lowering body mass index (BMI) — a measure of body fat based on height and weight, with a BMI of 30 kg/m or more defined as obese. This effect was biggest for those who were considered to have obesity.

Furthermore, a smaller study on metformin for weight loss found that the average amount of weight lost in 154 patients was between 5.6 and 7 kg (that’s roughly between 13 and 15 pounds).

So, although its FDA-approved purpose is to help blood sugar control, there’s definitely promising evidence that metformin treatment could work to help reduce excess body weight. And experts have some ideas as to how metformin for weight loss works.

One theory is that metformin works as an appetite suppressant, both directly and indirectly. Metformin, like Wegovy and Ozempic, increases secretion of the hormone GLP-1, which sends a signal to your brain that you’re full and helps reduce calorie intake.

Metformin may also make you more sensitive to leptin, a hormone that helps control appetite.

Another idea behind metformin-related weight reduction is that the medication promotes insulin sensitivity.

The food we eat is converted into glucose or sugar, and when glucose enters the bloodstream, your pancreas releases the hormone insulin to provide you with energy.

Some people’s bodies may fail to efficiently use or store glucose. This is called insulin resistance, and your body creates more of the hormone to try and compensate for higher glucose levels.

These higher blood sugar levels can eventually lead to prediabetes and type 2 diabetes.

Metformin has been shown to increase insulin sensitivity — AKA reduces insulin resistance — and make sure your body is getting energy from your food intake.

Another way metformin may prevent weight gain? By producing short-chain fatty acids that alter your gut microbiome, which can improve metabolism and suppress appetite. These changes to your gut microbiome can also lead to gastrointestinal issues like stomach pain, but the bright side is that this can further reduce your appetite.

Being overweight or having obesity can raise your risk for type 2 diabetes, and losing weight may help prevent developing diabetes, according to the American Diabetes Association (ADA).

Although it’s not an FDA-approved weight loss drug, you can see why some healthcare providers prescribe metformin off-label for weight management. But what’s the right dosage of metformin for weight loss?

For diabetes treatment, the ADA recommends 850 mg once a day for one month, with the possibility of increasing the dosage to twice daily, to be taken at the same time. But for weight loss, the dosage may be different.

Whatever the reason you’re taking metformin, it’s important to start low and go slow, and work with a professional. Your dosage will depend on your medical conditions, how much you weigh, your kidney function and more. Your provider is likely to start you on a smaller dose to help your body acclimate to the medication, and reduce the severity of side effects. 

Seeking medical advice from a healthcare provider is the best way to find which dosage of metformin for weight loss and/or diabetes prevention is best for you.

With the use of weight loss drugs on the rise, it’s no surprise that metformin has entered the discussion. But can metformin lead to weight loss?

  • Metformin, which is approved by the FDA for type 2 diabetes, works to decrease high blood sugar levels. While not designed to be a weight loss drug, research has found a connection between metformin and weight loss.

  • Being overweight or having obesity can lead to diabetes, which may explain why healthcare providers prescribe metformin for weight loss to prevent prediabetes or type 2 diabetes.

  • Researchers believe that metformin weight loss occurs because the drug promotes insulin sensitivity, which allows glucose from the food you eat to be properly converted to energy or stored. There’s also a theory that metformin works as an appetite suppressant by increasing your levels of the hormone GLP-1.

While more research may be needed for full FDA approval as a weight loss medication, there’s a lot of evidence that metformin can lead to weight loss, and it’s often prescribed off-label for this reason. Hers offers access to metformin for weight loss as part of a holistic weight loss treatment program, after a consultation with a healthcare provider.

But whether or not you go the metformin route, healthcare providers recommend plenty of other tried and true habits to shed extra pounds, such as eating a healthy diet, getting regular exercise like walking, aiming for seven to nine hours of sleep and more.

We also understand that this might just be the beginning of your journey to feeling your best in the skin you’re in. If you want to learn about other weight loss treatments, we have you covered.

11 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

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  7. Seifarth, C., Schehler, B., & Schneider, H. J. (2013). Effectiveness of metformin on weight loss in non-diabetic individuals with obesity. Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association, 121(1), 27–31. Retrieved from https://pubmed.ncbi.nlm.nih.gov/23147210/
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  10. Extra Weight, Extra Risk | ADA. (n.d.). American Diabetes Association. Retrieved from https://diabetes.org/healthy-living/weight-loss/extra-weight-extra-risk
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This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Craig Primack, MD, FACP, FAAP, FOMA

Dr. Craig Primack MD, FACP, FAAP, FOMA is a physician specializing in obesity medicine.

He completed his undergraduate studies at the University of Illinois and subsequently attended medical school at Loyola University — The Stritch School of Medicine. 

He completed a combined residency in Internal Medicine and in Pediatrics at Banner University- Phoenix, and Phoenix Children's Hospital. He received post-residency training in Obesity Medicine and is one of about 7,000 physicians in the U.S. certified by the American Board of Obesity Medicine.

In 2006, Dr. Primack co-founded Scottdale Weight Loss Center in Scottsdale, Arizona, where he began practicing full-time obesity medicine. Scottsdale Weight Loss Center has grown since then to six obesity medicine clinicians in four locations around the greater Phoenix Metropolitan area.

From 2019–2021, he served as president of the Obesity Medicine Association (OMA), a society of over 5,000 clinicians dedicated to clinical obesity medicine. He has been on the OMA board since 2010, currently serving as ex-officio trustee.

Dr. Primack routinely does media interviews regarding weight loss and regularly speaks around the country educating medical professionals about weight loss and obesity care. He is co-author of the book, “Chasing Diets.”

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