Should You Take Metformin For Weight Loss?

Metformin is an antihyperglycemic drug that lowers blood glucose levels to treat and manage type 2 diabetes. The latest data shows that just over 34 million people in the U.S. alone have diabetes,¹ accounting for approximately 10% of the entire population. While metformin is typically used for diabetes management rather than weight loss purposes, there is also evidence that it supports weight loss.²

Can metformin help you lose weight?

Obesity is a serious global health concern, especially in the U.S. where 42.4% of Americans were classified as obese between 2017-2018.³

This disease results in a cascade of other health problems such as cardiovascular diseases (CVD) and type-2 diabetes. It can also lead to various types of cancer, which contribute to the deaths of many Americans every year.

Metformin is a first-line oral medication commonly prescribed to patients with type 2 diabetes or prediabetic patients with at least one cardiovascular disease risk factor, such as hypertension (high blood pressure).⁴ ⁵

Not only does metformin reduce blood glucose levels, but it can also induce moderate weight loss. This effect has been observed in both diabetic and non-diabetic individuals.⁶ ⁷

Although metformin has been shown to promote weight loss, just how it works remains unclear. Medical researchers have suggested that it may affect how the brain regulates appetite and food intake.⁶ Other studies have examined metformin’s effect on peripheral brain pathways, such as fat storage, hormone sensitivity, and body clock.

Metformin does not cause immediate weight loss. Instead, weight loss occurs gradually over a long period of time. A long-term diabetes prevention program (DPP) study observed weight-loss effects from metformin use over a period of up to two years, with participants losing an average of approximately six pounds after the first year and just under five pounds after two years.²

Over the next ten years, researchers followed up with patients who had responded well to metformin treatment, which showed they had maintained their weight loss.²

In a shorter study, metformin use was similarly found to have resulted in weight loss of up to 12 pounds in overweight or obese non-diabetic patients.⁷

These studies highlight how the effect metformin has on weight loss differs from person to person.²

Can metformin help you lose weight quickly?

Since metformin does not cause immediate weight loss, combining it with a healthy diet and regular exercise is an optimal approach to speed up the weight loss process.²

Another DPP study that followed up with patients taking metformin or implementing intensive lifestyle changes for almost three years after the study ended observed an average weight loss ranging between five to 12 pounds.⁸

A longer-term study showed that a significant proportion of patients taking metformin or those undergoing intensive lifestyle changes achieved weight loss of more than 5% over a 15-year period.⁹

Therefore, combining both metformin use and a healthy lifestyle may promote quicker and more significant weight loss.

Is metformin safe?

Clinical studies have not shown any major safety concerns associated with metformin use. In fact, there is limited evidence indicating starting treatment at a low dose of 500mg/day and increasing it slowly over time may mitigate any gastrointestinal side effects associated with metformin treatment.¹⁰ If the dose is tolerable, it can be slowly increased up to 2000mg/day.¹⁰

Recent research has also demonstrated that a low dose of metformin (1000-1500mg/day) can promote weight loss in non-diabetic individuals.¹¹ If you experience any side effects, you should consult your healthcare professional to discuss whether metformin is right for you.

What are the risks with metformin?

Despite metformin being a relatively safe drug, there are a few potential risks to note before starting treatment.

Blood glucose

Metformin acts by lowering blood glucose levels, so if your blood glucose levels are typically low (hypoglycemia), you should avoid taking this medication.

Co-administration of metformin with other diabetic therapies may also result in adverse drug interactions.²

Make sure to discuss with your healthcare professional whether you should take metformin. If you are taking it, check-in regularly with your doctor to monitor your blood glucose levels in order to adjust your dose to minimize any complications.

Renal impairment and lactic acidosis

Metformin may not be appropriate for you if you have a history of renal impairment.¹² This may result in lactic acidosis, the overproduction of lactic acid, which is a relatively rare side effect of metformin treatment. It is unclear whether metformin causes lactic acidosis or whether other predisposing factors cause it.¹³

If you have a history of renal complications, talk to your doctor to discuss whether metformin is an appropriate drug for you.

Gastrointestinal issues

Gastrointestinal problems (diarrhea, vomiting, nausea, and/or abdominal cramps) are a common side effect of taking many types of medication, including metformin. While the prevalence and severity tend to be relatively minor, you should consult your doctor if you are experiencing any issues.

The lowdown

Metformin is a common form of treatment for diabetic patients, but studies have shown that it also assists with weight loss. Generally, metformin is considered safe and well-tolerated with few side effects.¹⁴ However, the weight loss effects of metformin vary from person to person.

Metformin is not currently recommended as a therapy on its own for overweight or obese patients who do not also present with metabolic complications, such as diabetes or cardiovascular disease.

To find out whether metformin is a safe and appropriate treatment to help you lose weight, you should talk to your doctor or healthcare professional.