Table of Contents

Metformin is a popular medication for treating Type 2 diabetes, but did you know it’s also used for off-label purposes? The various uses of this drug may surprise you. Doctors often prescribe it for weight loss, polycystic ovary syndrome (PCOS), and gestational diabetes. Among these non-FDA-approved uses, people are particularly interested in its weight loss benefits. Can this antidiabetic drug help you slim down? Is metformin even effective for weight loss? What are some key things you should know before using it off-label?

Key Takeaways

  • Metformin belongs to a class of drugs known as biguanides, and it’s the eighth most commonly prescribed antidiabetic drug.
  • It comes in different formulations — metformin immediate-release (IR), metformin ER, and metformin hydrochloride extended-release oral suspension. They vary in dosing, form, and how fast they work.
  • Metformin may lead to modest weight loss. In one study, participants lost 2.1 kg or 2.06% of their body weight after taking metformin.
  • Metformin doses are highly individualized, but doctors often prescribe the lowest 500 mg dose for new users, then gradually increase it based on the patient’s tolerance to side effects.
  • Up to 30% of people who use metformin experience nausea, diarrhea, and vomiting. Long-term use is associated with vitamin B12 deficiency.

What Is Metformin and Why Is It Used?

What is Metformin?

Metformin is the eighth most commonly prescribed medication for Type 2 diabetes. The American Diabetes Association (ADA) considers it the first-line agent for treating diabetes in adults and children who are at least 10 years old. 

It was approved by the FDA in 1994 and belongs to a class of drugs known as biguanides. Like other antidiabetic drugs, it helps lower blood sugar levels by improving how your body responds to insulin and reducing the production of glucose in the liver. It’s often used alone or with other medications like insulin to manage blood glucose. 

Metformin is available in tablet and liquid forms and comes in different formulations. 

    • Metformin IR: Sold under the brand name Glucophage. It works faster but requires twice-daily dosing. 
    • Metformin ER: Sold under Glucophage XR, Fortamet, and Glumetza. It releases metformin slowly over time and requires once-daily dosing.
    • Metformin hydrochloride extended-release oral suspension: Sold under the brand name Riomet ER and is the first and only FDA-approved liquid metformin. It’s taken once daily with the evening meal. 

Does the FDA Approve Metformin for Weight Loss?

No, metformin is not FDA-approved for weight loss. However, some users report it has helped them slim down. Clinical trials on this drug have primarily focused on its glucose-lowering effects. However, it’s true that some people may lose weight after taking it. This secondary benefit is due to its impact on appetite. 

Metformin helps lower blood sugar levels and improve insulin sensitivity. These benefits indirectly reduce your appetite, decreasing the amount of food you eat. Some doctors prescribe it off-label, particularly to those with weight problems. 

Talk to your doctor if you’re curious about metformin for weight loss but don’t have diabetes. They can help you decide if it’s safe for you.

Does Metformin Help You Lose Weight? 

Yes. Here are different ways metformin helps you slim down.

    • Reduces appetite: Metformin can help minimize blood sugar spikes, which means fewer cravings. 
    • Improve insulin sensitivity: It lowers insulin resistance, which positively impacts your appetite.
    • Reduce liver glucose production: It helps stabilize blood sugar levels, which reduces how frequently you feel hungry. 
    • Prevent fat gain: Its direct and indirect effects on your appetite will help prevent further weight gain. 

Because of these benefits, doctors may prescribe metformin for weight loss in people without diabetes. 

How Much Weight Can You Lose on Metformin?

Person standing on weight scale

In one study published by the American Diabetes Association, participants who took metformin lost 2.1 kg or 2.06% of their body weight during the 2-year double-blind period. 

Researchers called this study the Diabetes Prevention Program (DPP), involving 3,234 participants from various clinics throughout the country. They were randomized to receive metformin or a placebo. 

Participants took an 850 mg dose of metformin once a day. After one month, the dose was increased to 850 mg twice daily. This dose increase was delayed in participants who experienced severe side effects, giving their bodies more time to adjust to the drug.

Below is a summary of the study’s findings:

    • People on metformin lost an average of 2.06% of their body weight, while the placebo group lost only 0.02%. 
    • The metformin group reduced their waistline by 2.13 cm compared to only 0.79 cm in the placebo group. 

This study concluded that the more consistently participants took metformin, the more weight they lost. The results aren’t as dramatic as those of newer antidiabetic drugs like semaglutide, but they still improved participants’ overall health. 

How Much Metformin Should You Take to Lose Weight?

Woman hodling metformin pills in one hand and a glass of water in the other

There’s no one-size-fits-all metformin dose for weight loss. Your doctor will create a treatment plan tailored to your unique health situation and needs.

For Off-label Weight Loss

According to the National Library of Medicine, the recommended initial dose for metformin IR for off-label weight loss is 750 mg up to 2000 mg daily, divided into 2 to 3 doses. This suggested dose specifically applies to people who use antipsychotic medications. These drugs are known to cause weight gain as a side effect. The maximum dose is 2550 mg daily.

For metformin ER, the starting dose is typically 500 mg. This is increased by 500 mg increments every 2 to 6 weeks until the maximum dose of 1000 mg to 2000 mg daily is reached. 

For Type 2 Diabetes

If you have diabetes, below is the recommended treatment dose:

Metformin IR

    • Start with 500 mg once or twice daily or 850 mg once daily.
    • The dose is typically increased weekly in increments of 500 mg or 850 mg. 
    • The standard maintenance dose is 850 mg or 1000 mg twice daily. 

Metformin ER

    • Start with 500 mg or 1000 mg once daily. 
    • The dose is increased weekly in increments of 500 mg for up to 6 weeks.
    • The recommended maximum dose is 2000 mg once or twice daily.

Metformin is typically combined with a healthy diet and regular exercise for optimal results. 

Articles you may also be interested in

Can People Without Diabetes Use Metformin for Weight Loss?

Yes, doctors may prescribe metformin to individuals without diabetes, but it’s considered off-label. If you want to try it, make sure you work with your healthcare provider to monitor the side effects. People without diabetes should only take metformin under medical supervision. 

How Long Before You See the Results?

It may take several weeks to months before you notice some changes in your body size. People with diabetes can lose around 2% to 3% of their body weight within the first year of treatment. However, results vary from person to person. How much you eat or how frequently you exercise also affects the outcomes. 

Is it possible to lose weight on metformin for a short period? How much weight can a non-diabetic person lose on metformin for two months? In an earlier study published in the National Library of Medicine, people who were obese but not diabetic who took metformin for 15 days lost an average of 2.8 kg (6.2 lbs). They also lost about 1.4 kg (3.1 lbs) of body fat. 

Metformin reduces appetite, resulting in lower food intake and, consequently, weight loss. Participants who ate less were the ones who lost the most weight and fat. 

What Are the Side Effects of Metformin?

Below are common side effects of metformin for weight loss and diabetes that affect up to 30% of users:

    • Diarrhea 
    • Nausea 
    • Vomiting

Some less common adverse reactions include: 

    • Diaphoresis
    • Hypoglycemia
    • Rhinitis 
    • Weakness
    • Chest discomfort
    • Headache

Long-term use of metformin can reduce vitamin B12 levels in the body. This adverse reaction often affects people with anemia or peripheral neuropathy. Sometimes, patients may need to take vitamin B12 supplements to prevent deficiency. 

Most people can tolerate metformin well, but doctors usually adjust the dose for those who don’t. If you notice persistent or worsening symptoms, inform your doctor immediately.

Tips to Lose Weight Fast on Metformin

Dumbells, apples measuring tape and diabetes monitor on a counter

Like other antidiabetic medications, metformin is recommended alongside healthy lifestyle habits. Here are some tips to speed up weight loss with metformin. 

  • 1

    Reduce Your Carbs

    Switching to a low-carb diet can improve insulin sensitivity and boost metformin’s effects.
  • 2

    Move Your Body

    Engage in regular physical activities, such as walking, strength training, or any activities you enjoy.
  • 3

    Be Mindful of What You Eat

    If you’re prone to late-night cravings, try eating smaller portions throughout the day. Include more protein and fiber in your meals to prevent hunger pangs.
  • 4

    Be Consistent With Your Dosing Schedule

    Take metformin at the same time every day. Set an alarm or use a pill dispenser to avoid skipped doses.
  • 5

    Stay Well-hydrated

    Drinking lots of water can help tone down nausea, headache, and other gastrointestinal side effects.

These healthy habits can help you maximize the benefits of your metformin treatment.

Metformin May Be Prescribed for Off-label Weight Loss

Metformin is approved for treating Type 2 diabetes, but some doctors may prescribe it for off-label weight loss. It doesn’t cause rapid weight loss, unlike newer antidiabetic medications like Ozempic or Wegovy. HHowever, this gradual and steady weight loss tends to cause fewer severe stomach-related side effects, which some patients may find more tolerable.

Weight loss from metformin is typically modest — just a few pounds over several months — and results vary between individuals. A key consideration is that long-term metformin use may lead to vitamin B12 deficiency. Be sure to talk to your doctor about potential side effects before beginning treatment.

Frequently Asked Questions

Yes, metformin can make you lose a few pounds. You need to combine it with healthy lifestyle habits for optimal weight loss results.

There’s no standard metformin dose for weight loss. Doctors typically recommend starting with the lowest 500 mg dose, then increasing it gradually each week until you achieve your ideal body size.

People without diabetes who take metformin may lose weight. But alongside this benefit, they may also experience side effects like nausea or vomiting. For off-label use, metformin should always be taken under medical supervision.

Hitting the gym regularly, eating nutritious foods, and staying consistent with your treatment are a few ways to lose weight fast with metformin.

Doctors recommend taking metformin with meals to minimize the stomach-related side effects. The best time can either be right after breakfast or dinner.

Metformin helps stabilize blood sugar levels by reducing how much glucose the liver produces. It also improves insulin sensitivity. All these benefits help reduce appetite, leading to lower food intake and gradual weight loss.

No. There are no studies proving that metformin causes weight gain. In fact, some doctors prescribe it specifically for weight loss.

Original Publish Date: 1/13/2023 – Updated 6/27/2025