Does Metformin Cause Weight Loss?
Key takeaways:
Metformin is a prescription medication that’s FDA approved to lower blood glucose (sugar) levels in people with Type 2 diabetes. It can also contribute to modest weight loss.
On average, people with diabetes lose about 4 lbs to 6 lbs while taking metformin. However, it isn’t approved or widely recommended to be used as a weight loss pill.
There are a few reasons that people can lose weight while taking metformin. It lowers how much glucose your liver makes, and it can also lessen your appetite.
Metformin is a first-choice treatment for managing Type 2 diabetes. And it’s generally very effective at its job. But there’s a lot to know about metformin’s many uses, the side effects it can cause, and who should take it.
One hot topic of discussion when it comes to metformin is whether the medication can help you lose weight. The answer is yes — to a degree.
Most people who are prescribed metformin take it to treat diabetes or prediabetes. And weight loss is often an important part of addressing these conditions. Decreasing blood glucose (sugar) while also lowering body weight is an ideal combination for many people.
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Does metformin help with weight loss?
Yes. Metformin can promote weight loss. It can also lead to a reduction in waist size. Large research studies have found these to be valuable benefits of metformin. But the amount of weight people lose while taking metformin is a point to explore.
What is the average weight loss with metformin?
The amount of weight loss with metformin varies by person. But some data is available to provide a general idea.
There have been several studies on metformin’s effect on weight loss. The largest study to date found that people lost an average of 4 lbs to 5 lbs while taking it. Another study had similar results. Participants lost a little over 6 lbs on average after 5 years. A third, shorter-term study reported a higher level of weight loss. It found that people taking metformin for a little over 6 months dropped an average of 8 lbs.
However, there’s still some confusion on metformin’s true role in weight loss. Some people don’t experience noticeable weight loss while taking the medication. In fact, many experts describe metformin as a medication that’s weight-neutral with a modest potential for weight loss.
Weight loss and other diabetes medications
Metformin isn’t the only diabetes medication that can reduce body weight. In fact, its weight loss effects are milder than some other diabetes medications, such as glucagon-like peptide-1 (GLP-1) agonists like Ozempic (semaglutide). These medications can help reduce body weight by as much as 15%.
How does metformin work for weight loss?
There are several explanations for how metformin can help lessen body weight. These include:
Lowering how much glucose your liver makes, so the amount of glucose converted into fat is also lower
Suppressing your appetite by affecting certain digestive hormones
Altering the bacteria and viruses that live in your gut (also called the gut microbiome)
Reversing some natural parts of getting older, such as a tendency to store more fat
Stomach-related side effects of metformin, such as nausea, diarrhea, and bloating, may also cause you to eat less, which could affect your body weight.
Is it OK for people without diabetes to take metformin?
Sometimes. Metformin won’t help everyone lose weight. Among people who don’t have diabetes, metformin is mostly effective at lessening body weight and waist size in those who have obesity (a BMI of 30 or higher). Other people who have overweight may not see the same effects.
Although metformin has many potential benefits, it’s important to have a discussion with your healthcare provider about whether it’s appropriate for you. Taking metformin for weight loss without a diagnosis of Type 2 diabetes is considered an off-label use. In other words, the medication is not FDA approved for this purpose.
Is metformin a safe way to lose weight?
Metformin is considered a safe treatment for Type 2 diabetes and prediabetes. If you have either of these conditions and take metformin to lower blood glucose, you may see weight loss as well. This is particularly likely if you pair metformin with a diabetes-friendly diet and regular exercise.
However, it isn’t widely recommended to take metformin solely for weight loss. There are other treatments that are likely better suited to be used as weight loss medications. Your healthcare provider can help you decide if metformin would be a safe and appropriate weight loss treatment for you.
Metformin side effects to keep in mind
As with many medications, metformin has some side effects to keep in mind. It rarely causes low blood glucose (hypoglycemia), but it’s known to cause certain gut-related issues, such as:
Diarrhea
Upset stomach
Gas
Nausea
Vomiting
Taking metformin with food or switching to an extended-release (ER) formulation may help prevent or ease these side effects.
Lactic acidosis and low levels of vitamin B12 are two rare but serious side effects that could occur when taking metformin. Other long-term side effects have also been reported, but the likelihood of them happening is less clear. There have also been a few myths about metformin’s effects on the kidneys, liver, and potential for cancer, but they have been debunked.
Who should not take metformin?
Metformin is not right for everyone. It’s cleared out of your body through the kidneys. If you have low kidney function, you may not be eligible to take it. Metformin itself does not affect kidney health, but if you have existing kidney problems, your body might not clear the medication out of your system properly. This can lead to extra side effects.
What’s more, people with Type 1 diabetes or certain types of liver problems should not take metformin. Talk to your healthcare provider about whether metformin is appropriate for you.
The bottom line
Metformin can lead to modest weight loss. It can help people with diabetes lose an average of 4 lbs to 6 lbs, but results vary. It’s typically not recommended to take metformin for weight loss unless you have diabetes or prediabetes. Talk to your healthcare provider about whether metformin would be safe and effective for you.
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References
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ElSayed, N. A., et al. (2023). 9. Pharmacologic approaches to glycemic treatment: Standards of Care in Diabetes—2023. Diabetes Care.
Glueck, C. J., et al. (2001). Metformin reduces weight, centripetal obesity, insulin, leptin, and low-density lipoprotein cholesterol in nondiabetic, morbidly obese subjects with body mass index greater than 30. Metabolism: Clinical and Experimental.
Kahm, S. E., et al. (2006). Glycemic durability of rosiglitazone, metformin, or glyburide monotherapy. The New England Journal of Medicine.
Pu, R., et al. (2020). Effects of metformin in obesity treatment in different populations: A meta-analysis. Therapeutic Advances in Endocrinology and Metabolism.
The Diabetes Prevention Program Research Group. (2012). Long-term safety, tolerability, and weight loss associated with metformin in the diabetes prevention program outcomes study. Diabetes Care.
Yerevanian, A., et al. (2020). Metformin: Mechanisms in human obesity and weight loss. Current Obesity Reports.
