Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to weight loss.
Metformin is a prescription medication used to treat and manage type 2 diabetes. However, it's increasingly being used "off label" for weight loss.
But is metformin actually shown in research studies to cause weight loss? And if so, how much weight loss does it cause on average? How do real patients describe the effects of metformin on their weight? And what dosage is typically used?
In this article we'll answer all of these questions and more as we analyze medical studies on metformin to determine if the drug actually causes weight loss, and if so, how much.
We'll discuss whether or not the drug is FDA-approved for weight loss, feature real patient reviews discussing the drug's effect on their weight, and explain how metformin works.
Does Metformin Cause Weight Loss?
Weight loss was initially documented as a side effect of metformin in early clinical trials on the drug for diabetes, as we documented in our metformin reviews article, and further research has been conducted specifically on metformin and weight loss.
A 2018 meta-study concluded that metformin was effective for weight loss. Patients lost an average of 4.92 pounds more on metformin than on placebo pills. The study durations ranged from around six months to four years, so this is a modest reduction in weight over that time period.
A medical review on metformin and obesity was published in the Current Obesity Reports journal, and documented that patients taking metformin lost 4.63 pounds over the course of a three year period.
A recent clinical trial found metformin to be effective for weight loss even in non-diabetic patients. Over the course of six months, obese non-diabetic patients taking metformin lost an average of 5.6% of their body weight, which equates to a weight loss of 14 pounds for someone weighing 250 pounds, while the control group only lost an average of 0.8% of their weight.
Metformin appears to be potentially effective for weight loss in both diabetic and non-diabetic patients based on the research cited above.
But how do real users describe the effects of metformin on weight loss? We'll feature some patient reviews in the next section.
Real Users Review Metformin for Weight Loss
A YouTube creator named "Kate Tries" tried metformin for weight loss for two weeks, while having PCOS:
A YouTube creator named Jasmine Airdelle shared her experience using Metformin for PCOS and discusses the weight loss effect:
What Dose is Used for Weight Loss?
The dosage of metformin used in clinical studies for weight loss depends on the age of the patient.
We want to clarify here that we do not recommend taking metformin for weight loss; we are simply reporting the research outcomes from published clinical trials on the topic. This information may be useful for patients to discuss with their doctor.
A 2019 medical review on metformin for weight loss in overweight patients without diabetes reported that 2,000 milligrams (mg) per day was most effective for adolescents, while 3,000 mg per day for a maximum of six months was most effective for adults.
A 2020 meta-study analyzed results from 21 clinical trials on metformin and weight loss. The effective dose used in the studies ranged from 1,000 mg per day to 2,550 mg per day.
But is this medication even approved by the FDA for weight loss? We'll answer that question in the next section.
Is Metformin FDA-Approved for Weight Loss?
Metformin is not approved by the FDA for weight loss at the time of updating this article. It is only approved for the treatment of type 2 diabetes according to the medication’s label.
For a drug to be approved by the FDA, it must demonstrate consistent statistically significant improvements across various clinical trials that are well-designed. The FDA considers metformin’s performance in weight loss trials too inconsistent for the regulatory agency to approve the drug for weight loss at this time.
Metformin may be approved as a standalone treatment for weight loss in the future, but at this time using metformin for weight loss alone would constitute an "off-label" use; unapproved by the FDA.
But how does metformin actually cause weight loss? We'll answer that question in the next section.
How Does Metformin Work?
Metformin primarily works by increasing insulin sensitivity, according to a 2022 medical review.
Metformin is a member of a class of drugs called biguanides, which affect several biological processes: they decrease the liver’s production of glucose, decrease how much glucose is absorbed by the intestines, and decrease blood levels of glucose.
The reason metformin may be effective for weight loss is because it normalizes processes like pre-diabetes and diabetes which cause downstream weight gain in some patients. There’s a medical term called “insulin-associated weight gain” which is documented to affect diabetics.
Because metformin directly improves insulin resistance, it may counteract insulin-associated weight gain and halt (and even reverse) overall weight gain.
This suggests that metformin may not be likely to be effective in patients without any blood sugar or insulin issues. The study we referenced previously which found metformin to be effective for weight loss in non-diabetic patients still included a patient population with insulin dysregulation.
Pharmacist on Metformin for Weight Loss
One of the most popular YouTube videos on metformin for weight loss comes from a channel called “Pharmacist Tips.”
The video has nearly 200,000 views at the time of publishing this article, and breaks down medical research on whether metformin is effective and safe long-term for weight loss:
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