Metformin is a medication used to treat type 2 diabetes mellitus.
It may also be used for polycystic ovary syndrome (PCOS), insulin resistance, and prediabetes.
While metformin is not a weight-loss drug, because of how it affects glucose and insulin in the body, it may help people with blood sugar problems lose weight.
In this article, we’ll look at research on how metformin causes weight loss, side effects, and possible drug interactions.
Does Metformin Help With Weight Loss?
Research does not have a clear answer as to why metformin may cause weight loss.
It is most likely due to several different effects of the drug:
- Reduced hunger: Metformin plays a role in hunger cues. Research notes that people who take metformin have lower hunger levels. The drug does not suppress the appetite but instead changes the part of the brain that regulates appetite desire. Metformin may lead people to eat less at each meal, which may help them lose weight.
- Side effects of the drug: Metformin may cause nausea and diarrhea. Initially as a person is adjusting to the medication, the combination of an upset stomach, eating less, and having diarrhea may cause a temporary drop in weight.
- Better insulin and glucose balance: Since metformin improves sensitivity to insulin and reduces how much glucose circulates in the blood, it may decrease how much excess glucose is stored as fat. Over time, this could result in weight loss.
- Gut health: Research shows that people living with obesity may have fewer short-chain fatty acids in the gut. These acids have a protective effect on many aspects of health, including weight. Metformin increases the production of short-chain fatty acids, which may contribute to weight loss.
Some research shows that metformin doesn’t affect weight beyond dietary and lifestyle changes that are likely made by people taking metformin.
Other research finds significant weight decreases in people who were obese, independent of lifestyle factors. Multiple studies report that metformin paired with a low-calorie diet reduces visceral body fat.
Is metformin an effective weight-loss pill?
Metformin is not a weight-loss medication. It isn’t prescribed for people who simply want to lose weight.
When metformin is indicated for health conditions, it may lead to weight loss as a side effect.
Can People Without Diabetes Take Metformin?
Some healthcare providers prescribe metformin to support weight loss in people who are obese and have other contributing factors such as insulin resistance.
Even without diagnosed type 2 diabetes or the signs of prediabetes, metformin may work to support weight loss when insulin may not be as effective in the body.
Not all obesity is associated with insulin-related problems, though.
Even if a medical provider prescribes metformin for weight loss, it will not do the job on its own.
Healthy lifestyle behaviors such as the below are needed to promote weight loss with metformin:
- Exercising for 30 minutes a day, five days per week
- Avoiding sugary beverages
- Drinking enough water
- Eating a balanced diet that’s rich in unprocessed foods
Precaution and Risks
Metformin carries a black box warning, the FDA’s strictest label.
In rare cases, metformin can cause lactic acidosis.
This condition occurs when too much metformin builds up in the body.
Lactic acidosis is a medical emergency and is potentially fatal if left untreated.
Metformin can also cause unsafe complications or interactions with the following health conditions:
- Kidney problems or disorders
- Metabolic acidosis
- Heart failure
- Before surgical procedures
- Before radiology procedures with iodine contrast
Metformin side effects
The common side effects of metformin are typically short-term while the body adjusts to the medication and include:
Over time, metformin may contribute to vitamin B12 deficiency or anemia.
Metformin drug interactions
There are many possible drug interactions with metformin.
Keep your medical provider and pharmacist informed about the prescriptions, OTC medicines, and supplements that you take.
Metformin can interact with the following:
- Oral contraceptives
- Beta blockers
- Calcium channel blockers
- Coenzyme Q10
- Green tea
When to See a Medical Provider
If you are trying to lose weight and feel that your efforts aren’t making enough progress, speak to a healthcare provider.
They can recommend potential medications or other support that could help.
While metformin is not a weight-loss drug, it may be effective to help some people lose weight.
A medical provider can determine if metformin may be appropriate for you.
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Frequently Asked Questions
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Glucophage (Metformin Hydrochloride) Tablets. (2017).
Combined Lifestyle Modification and Metformin in Obese Patients With Polycystic Ovary Syndrome. A Randomized, placebo-controlled, double-blind multicentre study. (2006).
Metformin and weight loss in obese women with polycystic ovary syndrome: comparison of doses. (2005).
Effect of long-term treatment with metformin added to hypocaloric diet on body composition, fat distribution, and androgen and insulin levels in abdominally obese women with and without the polycystic ovary syndrome. (2000).
Role of metformin in the management of polycystic ovary syndrome. (2010).
What causes the insulin resistance underlying obesity? (2014).
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Metformin-associated lactic acidosis: Current perspectives on causes and risk. (2016).