Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s) and published for informational purposes only. 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 there is some early research suggesting that the drug may cause weight loss in overweight and obese patients, and thus patients are curious about whether the drug is actually effective to use for this off-label purpose.
In this article we’ll review the clinical research on Metformin to determine if it’s actually safe and effective for weight loss, and we’ll share our thoughts on off-label drug use generally.
Research on Metformin and Weight Loss
After researchers began noting weight loss as a side effect of Metformin use in some medical trials, more research has recently been conducted specifically on whether Metformin can cause weight loss.
An extensive medical review of metformin and human obesity was published in the Current Obesity Reports journal which evaluated results from many individual clinical trials on the topic. The researchers found that Metformin was effective for both weight loss and also potentially for weight prevention on average.
The study authors noted that in a large study called the Diabetes Prevention Study, patients lost 2.1 kilograms (kg) which equates to 4.63 pounds (lbs) on average over the course of the trial.
A separate meta-study published in 2018 also concluded that Metformin was effective for weight loss. The average weight lost on Metformin compared to placebo was 2.23 kg (4.92 lbs). Most of the studies had a duration of around 6 months to 4 years, so this is a modest reduction in weight over that time period.
A recent clinical trial was fascinating because it found that Metformin was effective for weight loss even in non-diabetic patients. Over the course of 6 months, the obese patients lost an average of 5.6% of their weight, while the control group only lost an average of 0.8% of their weight.
Clearly Metformin is effective on average for weight loss. It appears to be definitively effective on diabetic patients, and early research is emerging suggesting the drug may be effective even for non-diabetic patients, but we believe that more research needs to be published to conclusively state this.
How Does Metformin Work?
Metformin primarily works by increasing insulin sensitivity, according to StatPearls, which is the largest free medical database in the U.S. and is maintained by the National Library of Medicine.
It’s 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.Â
Because Metformin directly improves insulin resistance, it may counteract this process and halt (and even reverse) weight gain. This research suggests that Metformin may not be likely to be effective in patients without any blood sugar or insulin issues. The study from the previous section which found Metformin to be effective for non-diabetic patients still used a patient group with insulin dysregulation.
Metformin Dosage for Weight Loss
The dosage of Metformin found effective 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 trials. This information may be useful for consumers generally, or for patients to speak with their doctor about.
A medical review of Metformin for weight loss in overweight people without diabetes found that 2,000 milligrams (mg) per day was most effective for adolescents, while 3,000 mg per day for adults for a maximum of 6 months was most effective.
A separate meta-study analyzed results from 21 individual clinical trials on Metformin and weight loss. The effective dose range from the studies ranged from 1,000 mg/day to 2,550 mg/day.
Is Metformin Approved by the FDA for Weight Loss?
Metformin is not approved by the FDA for weight loss. 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 in the health outcome over the course of multiple trials. According to the StatPearls resource referenced previously, Metformin’s performance in weight loss trials has been too inconsistent for the regulatory agency to approve the drug for weight loss at this time.
We believe that Metformin may be approved for weight loss in the near future since it clearly can cause weight loss on average in overweight diabetic patients, but we’ll wait for more research to emerge.
Do We Recommend Metformin for Weight Loss?
We do not recommend Metformin for weight loss. As we outlined in our article on how to lose weight fast, we believe it’s unsafe to use drugs off-label (meaning to use them in a different way than they’re approved by the FDA to be used).
While some doctors may prescribe medications off-label, we would recommend avoiding those doctors. The FDA is likely to have reviewed more relevant research about a drug than your local doctor, because it’s their entire job to do so. We trust the approval process of the FDA more than most doctors’ judgment in regard to off-label medication use.
There are a number of research-based treatments for weight loss which are either approved by the FDA or are dietary supplements or food (and thus don’t need to be approved by the FDA), so we find it illogical to use Metformin off-label for weight loss at this time.
Pharmacist’s Take
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 long-term for weight loss:
Natural Weight Loss Option
We recommend significantly increasing dietary fiber intake for patients looking to lose weight naturally. This is the most cost-effective, safe and side-effect-free weight loss option in our opinion.
According to medical research, fiber intake predicts weight loss. The science behind this process is simple: fiber is non-digestible plant matter that occupies space in the stomach and delays gastric emptying. It makes you feel full longer without adding calories.
Fiber is the reason why it’s challenging for most people to eat 1,000 calories of beans, rice and a side salad, but easy to eat 1,000 calories of pizza. The former option is much higher in fiber and the latter option is nearly devoid of fiber.
You can get fiber from whole foods like avocado, nuts, seeds, beans and fruits and vegetables. You can also get fiber from a dietary supplement if that’s more convenient. Just make sure the supplement contains no additive ingredients like cane sugar or artificial flavoring which would degrade the health benefits.
Aiming for a daily fiber intake of around 40 grams (g) may improve weight loss efforts, but we recommend that patients work with their doctor to gradually increase fiber rather than increase its intake all at once, which could cause digestive discomfort.
