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Metformin for Weight Loss: Mechanisms and Potential Side Effects

Metformin for Weight Loss: Mechanisms and Potential Side Effects
Dr. Constance Odom, MD Picture of Dr. Constance Odom, MD

Medically reviewed by

Written by our editorial team.

Last Edited 5 min read

With the obesity rate rapidly growing in America, many people are seeking new ways to lose weight. Fad diets can be hard to stick to. They are often ineffective, leading many people to turn to prescription medications to reach their weight loss goals. Many believe that Metformin, a diabetes drug, is effective in helping people lose weight. But does it work? The short answer is yes, it works. 

A 2013 study conducted by PubMed found Metformin to be effective in helping people lose weight. The study found that 154 patients with a high body mass index benefited from Metformin to lose weight. The study took place over six months and found that patients taking Metformin lost a considerable amount of weight when compared to participants who did not take Metformin.

Many patients taking Metformin lose an average of 15 pounds over the course of several months. The drug is especially effective in helping those with insulin resistance. Studies have found that obese patients taking Metformin lost an average of 3.2 percent of their body weight. This is a significant finding, considering that weight loss drugs were once the only options available for those seeking weight loss. 

What is Metformin?

Metformin is most often prescribed for patients with type 2 diabetes. The drug helps regulate blood sugar levels, allowing the body to better utilize insulin. It reduces glucose absorption from the intestines, lowers liver glucose production, and improves insulin sensitivity. 

Metformin is one of the few diabetes drugs that help people lose weight. Many diabetes drugs can lead to weight gain, so using Metformin may be beneficial for obese individuals with diabetes. 

How does it work?

Metformin begins working in your stomach the moment it is ingested. Many medical professionals think it alters the balance of digestive bacteria that exists naturally in the gut. It also may activate enzymes that allow the body to process fat more efficiently. Studies have found that many people taking Metformin for weight loss continue to lose weight after they stop taking the medication. 

Metformin helps bring down blood sugar in a few ways. It makes your muscles utilize insulin better. That way, glucose can get into the muscles more easily. As a result of this, glucose doesnât linger in the blood for too long. Metformin also causes the intestines to absorb less glucose from your food. 

Although Metformin was not originally to be a weight loss drug, weight loss is a beneficial side effect for those seeking weight loss. According to experts, you must take between 500 and 1,000 milligrams of Metformin per day to achieve weight loss. This drug reduces the amount of glucose that is released by the liver. As a result, existing insulin in the body works more effectively. This results in lower blood sugar levels.

Multiple Benefits of Metformin

It also sets off several other benefits, including better glucose metabolism and a lowered risk of diabetes complications. Studies have found that Metformin may reduce the risk of stroke, retinopathy, heart disease, and neuropathy. 

Metformin works by stopping the body from releasing large amounts of insulin into your bloodstream. As a result, the body begins to metabolize glucose properly. You tend to lose weight when your insulin resistance goes down. Metformin helps with weight loss, because reduced hunger is a side effect of the drug. The drug also minimizes blood sugar spikes that can make you feel hungry. 

Metformin Side Effects

While Metformin has many benefits for weight loss, the drug also has a few unwanted side effects. The more common side effects of Metmofmin are:

  • Abdominal or stomach discomfort

  • Cough or hoarseness

  • Decreased appetite

  • Diarrhea

  • Fast or shallow breathing

  • Fever or chills

  • A general feeling of discomfort

  • Lower back or side pain

  • Muscle pain or cramping

  • Painful or difficult urination

  • Sleepiness

Some experts believe that Metformin aids in weight loss because it raises the bodyâs leptin levels. Leptin creates feelings of fullness. Because of this increase in satiety, some people are inclined to eat less.

The weight lost from this drug comes mainly from fat stores and does not disrupt lean muscle mass. Many people taking Metformin experience a lower waist circumference. Body fat as a whole significantly decreases from this drug. In one study, researchers found that those who lost weight from Metformin can maintain that weight loss for over fourteen years. However, participants who did not take Metformin also kept the weight off for the same amount of time. For this reason, it is unwise to rely on Metformin as a primary aid for weight loss.  

Metformin may also lower your A1c. It can also prevent prediabetes from developing into full-blown diabetes. 

Is Metformin safe?

Research shows that it is effective in helping people of all ages lose weight. In a study of non-diabetic and obese teenagers, researchers found that teenagers involved in the study saw a significant decrease in their body mass index or BMI. 

At present, you can find ads online that advertise Metformin as a weight loss drug, even though it was primarily created to treat diabetes. Some people have considered using it primarily as a weight loss drug. 

Notwithstanding, those looking to take Metformin for weight loss should also implement other lifestyle changes, such as eating a healthy diet of lean meats and grains and staying active. Experts recommend exercising five days of the week and using two days as rest days. 

For those who need an added boost for weight loss, incorporating Metformin might be effective in reaching a healthy weight. Experts recommend 2,000 calories per day for women and 2,500 calories per day for men. When combined, all these factors help promote weight loss and a healthy BMI. 

It is beneficial for obese people with diabetes to take Metformin. It not only treats diabetes, but also helps diabetics to treat their condition and decrease body mass at the same time.  

There may be cases where a doctor will prescribe Metformin for weight loss, but it is meant primarily for those with diabetes or insulin resistance. For this reason, it is more beneficial for diabetics seeking weight loss to take this medication. Metformin is not typically prescribed for people with type 1 diabetes, so those with type 2 diabetes are most likely to benefit from its ability to cause weight loss.

In which cases should Metformim not be taken?

While Metformin has many benefits, it is also important to know the risks of the medication. You should not take Metformin if you have kidney disease or diabetic ketoacidosis. As with any medication, it is important to make sure you are getting the nutrients you need for your body to function properly. Also be aware that in rare cases, Metformin may cause the development of lactic acidosis, a rare but serious condition. 

Key recommendation to avoid side effects when you are taking Metformin:

  • Inform your doctor about any other medications you're taking before starting Metformin.

  • Start with a small dose as prescribed by your doctor and gradually increase it.

  • Take Metformin at the same time every day for consistency.

  • Be vigilant for potential side effects like loss of appetite, metallic taste in mouth, and nausea.

  • To prevent nausea, take Metformin with food; eat meals when hungry and consider small meals throughout the day.

  • If experiencing diarrhea, increase fluid intake with water and fruit juices like apple juice and lemonade.

  • Watch for signs of vitamin B12 deficiency such as muscle weakness or vision problems; seek medical attention if necessary.

  • Contact your doctor if experiencing sweating, confusion, difficulty concentrating, or symptoms of low blood sugar like brain fog.

Metformin vs. Other Medications:

Metformin alone is an effective diabetes treatment option. However, it is not the only diabetes drug with the ability to cause weight loss. Dapagliflozin, another diabetes medication, was found to promote weight loss in people who take the medication. However, some patients who take Metformin may initially see an increase in weight before they actually lose weight.

All medications affect people differently, so what may work for one person may not work for another.

You may be interested in reading the following contents:

  1. Metformin vs. Mounjaro for Weight Loss

  2. Acarbose vs Metformin: What Studies Say

  3. Wegovy vs Metformin: Differences and Similarities

  4. Rybelsus vs Metformin: What's The Difference?


This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your physician about the risks and benefits of any treatment. Nu Image Medical may not offer the medications or services mentioned in this article.