Metformin, a medication long used to treat type 2 diabetes, has recently gained attention for a different reason—its potential role in weight loss. While new weight loss drugs such as semaglutide (marketed as Ozempic and Wegovy) have dominated the market, some patients are turning to metformin as a more affordable alternative. But does it really work for weight loss? Here’s everything you need to know about this decades-old drug, its history, benefits, risks, and why experts remain cautious about its off-label use for shedding extra pounds.
What is Metformin?
Metformin is an oral medication primarily prescribed for managing type 2 diabetes. It belongs to the biguanide class of drugs and works by lowering blood sugar levels. The drug improves insulin sensitivity and reduces the amount of glucose produced by the liver, making it an effective treatment for people with diabetes.
The origins of metformin can be traced back to a natural source—French lilacs (Galega officinalis). Researchers discovered that compounds in this plant had glucose-lowering properties, leading to the development of metformin as a pharmaceutical treatment in the 1950s. Since then, it has become one of the most widely prescribed diabetes medications worldwide.
How Does Metformin Work?
Metformin primarily lowers blood sugar by:
- Reducing Liver Glucose Production: It decreases the amount of sugar produced by the liver, preventing excessive glucose release into the bloodstream.
- Enhancing Insulin Sensitivity: It helps the body’s cells respond better to insulin, allowing them to absorb glucose more efficiently.
- Slowing Sugar Absorption in the Gut: It reduces the amount of glucose absorbed from food, leading to better blood sugar control.
Unlike insulin or sulfonylureas (another class of diabetes drugs), metformin does not cause the body to produce extra insulin, which means it has a lower risk of causing low blood sugar (hypoglycemia).
Metformin and Weight Loss: What Does the Research Say?
Despite its primary role as a diabetes medication, metformin has been observed to cause modest weight loss in some patients. However, experts do not consider it a dedicated weight loss drug like semaglutide or liraglutide.
Reasons why metformin may aid weight loss include:
- Appetite Suppression: Some studies suggest that metformin reduces hunger, leading to lower calorie intake.
- Improved Insulin Sensitivity: Since metformin helps the body use insulin more efficiently, it may prevent excessive fat storage.
- Reduction in Fat Absorption: Some research indicates that metformin may limit the amount of dietary fat absorbed by the intestines.
While these mechanisms contribute to minor weight loss, most patients only lose about 2-5 kg (4-11 lbs) over several months. In contrast, newer weight loss drugs like semaglutide can lead to significantly greater weight reduction.
Metformin vs. Semaglutide: The Super Bowl Controversy
During the 2025 Super Bowl, Hims & Hers, a telehealth company, promoted an injectable version of semaglutide at a lower price, making it seem more accessible. However, many patients later reported that they were prescribed metformin instead, likely due to shortages or affordability issues.
This led to confusion, as metformin does not have the same potent weight-loss effects as semaglutide. Unlike semaglutide, which mimics GLP-1 hormones to slow digestion and reduce hunger, metformin works primarily by regulating blood sugar. This means that while it may help with weight stabilization, it is not as effective as newer anti-obesity medications.
Experts warn that patients seeking weight loss solutions should not rely on metformin alone and should consult a doctor before considering any medication.
Who Should Take Metformin?
Metformin is FDA-approved for type 2 diabetes and is sometimes prescribed off-label for conditions such as:
- Prediabetes: To prevent progression to full-blown diabetes.
- Polycystic Ovary Syndrome (PCOS): To improve insulin resistance and regulate menstrual cycles.
- Gestational Diabetes: In some cases, to manage blood sugar during pregnancy.
However, it is not FDA-approved for weight loss, and doctors generally do not recommend it as a primary weight-loss solution.
Side Effects and Risks of Metformin
Metformin is considered a relatively safe medication with mild side effects. However, some people may experience:
- Gastrointestinal issues – Nausea, diarrhea, bloating, and stomach cramps are common, especially when first starting the drug.
- Vitamin B12 deficiency – Long-term use can reduce vitamin B12 absorption, potentially leading to anemia or nerve problems.
- Lactic acidosis (rare but serious) – In rare cases, metformin can cause a buildup of lactic acid in the blood, a life-threatening condition that requires immediate medical attention.
To minimize side effects, doctors often start patients on a low dose and gradually increase it.
Can Metformin Be Used for Weight Loss?
While metformin has been linked to slight weight loss, experts do not recommend it as a weight loss drug due to:
- Limited Effectiveness: Most patients only experience modest weight loss, which is much lower than that seen with GLP-1 receptor agonists like semaglutide.
- Lack of FDA Approval for Weight Loss: Metformin is only approved for diabetes management, meaning its off-label use for weight loss is not backed by strong clinical trials.
- Potential Side Effects: Although relatively safe, metformin still carries risks, particularly for those without diabetes or insulin resistance.
For individuals seeking weight loss solutions, lifestyle changes (healthy diet, exercise) and FDA-approved weight loss medications are considered more effective options.
Should You Take Metformin for Weight Loss?
Before considering metformin for weight loss, it’s important to speak with a doctor. They can determine whether it’s appropriate based on your health history, blood sugar levels, and weight loss goals.
Metformin may be beneficial for individuals with insulin resistance, prediabetes, or PCOS. However, for those without metabolic issues, its effectiveness for weight loss is questionable.
Alternatives like semaglutide (Ozempic, Wegovy), liraglutide (Saxenda), and tirzepatide (Mounjaro) have been scientifically proven to promote significant weight loss and may be better suited for individuals looking to manage obesity.
Metformin is a well-established medication for type 2 diabetes, with some minor weight loss benefits. However, it is not a dedicated weight-loss drug and should not be used as a replacement for newer medications like semaglutide.
The recent controversy surrounding Hims & Hers’ Super Bowl ad highlights the need for proper medical guidance when choosing weight loss treatments. Patients should be cautious about off-label prescriptions and consult healthcare professionals before starting any medication.
Ultimately, while metformin may aid in modest weight loss, its primary role remains diabetes management, and it should not be relied upon as a sole weight-loss strategy.
