Metformin for Weight Loss: Does It Really Work?

1. What is metformin?
2. Does metformin cause weight loss?
3. Who can take metformin?
4. Who can’t take metformin?
5. Side effects of metformin
6. Is Metformin safe?
7. Dosage and cost

If you struggle with weight gain, you’re not alone. Over 73% of adults in the United States over the age of 20 years old have measurements in the overweight or obese range according to BMI. But, losing a healthy amount of weight (as agreed upon with your healthcare provider) and keeping the weight off can be challenging for many–you might be curious about medications like metformin to help you on your weight loss journey. Though metformin wasn’t designed as a weight loss drug, research shows it may help people shed unwanted pounds. 

Metformin is a medication prescribed to treat type 2 diabetes (T2D). Metformin helps lower blood sugar levels in people who cannot meet their goals with diet and exercise alone. The American Diabetes Association (ADA) considers it the preferred first-line diabetes drug for diabetics ten years old and up.

Metformin’s primary purpose is to lower blood glucose (blood sugar) levels. It does this in three ways. First, it reduces glucose production in the liver. Second, it slows down glucose absorption through the intestines. Third, it increases insulin sensitivity to help the body better process glucose.

Metformin may be prescribed off-label for several other purposes. These include gestational diabetes (diabetes diagnosed during pregnancy), type 2 diabetes prevention, and polycystic ovary syndrome (PCOS). Providers also prescribe it to people taking antipsychotic medications to manage the weight gain experienced with those drugs.

Metformin is a safe and effective drug for treating type 2 diabetes, but does metformin help you lose weight? The answer is it may, for some. Metformin is not a replacement for healthy eating and exercise. 

New studies have shown that metformin may have other health benefits, and weight loss is high among them. At first, scientists thought metformin weight loss was a direct result of lowering glucose, but research shows there may be more to the side effect—metformin may lower food intake by reducing appetite. However, exactly how the drug curbs appetite isn’t fully understood.

Early research on metformin was limited to people with diabetes. Participants who took metformin saw small weight loss benefits versus placebo or other diabetes medications. Other studies found metformin treatment to be “weight neutral,” meaning that people neither gained nor lost weight while taking it. However, this was still preferable to other drugs that cause weight gain.

An early study of people with diabetes and morbid obesity found significant weight loss after 28 weeks of metformin alongside a healthy diet. Other risk factors for coronary heart disease were lowered as well, including fasting insulin, leptin, and LDL cholesterol. This study was small, however, and contained no placebo group.

Even in studies that indicated weight loss, the results were modest. One of the most extensive studies to date, performed by the Diabetes Prevention Program (DPP), tested metformin in people with prediabetes (those at risk for developing T2D). People randomly assigned metformin lost an average of 4-7 pounds.

Even for groups in which metformin shows clear weight benefits, it isn’t a magic pill by any stretch. The amount of weight reduced appears to level off over time. In the DPP study, 29% of people in the group taking metformin lost 5% or more of their body weight by the end of the first year. At the end of year two, 26% of the group had maintained their weight loss. The average reduction in waist size did not change much between year one and year two, either. However, these results were superior to results of the placebo group. 

The keyword regarding the effectiveness of metformin for weight loss is modest. Metformin can’t replace lifestyle changes like adopting a healthy diet and exercise routine. Weight loss tends to be small and takes time to achieve. But for people with diabetes or prediabetes, metformin may offer an extra boost.

In addition to those with type 2 diabetes, other people may benefit from metformin. Some people taking antipsychotic medications may develop a condition called metabolic syndrome. Weight gain and elevated lipids (triglycerides and cholesterol) are among the many signs of this syndrome. In one study, people on antipsychotics gained an average of eight pounds during the first twelve weeks of treatment. For people new to antipsychotics, those taking metformin saw significantly reduced weight gain, lower body mass index (BMI), and lower insulin resistance.

Metformin is not for everyone. The drug carries a black box warning from the FDA. You should not take metformin if you have severe kidney disease. Metformin may contribute to a condition called lactic acidosis, which can be life-threatening. If you are over 65 and have experienced any of the following, metformin might not be safe for you:

• Heart attack
• Stroke
• Diabetic ketoacidosis (blood sugar so high that it required emergency treatment)
• Liver disease
• Heart disease
• Coma
• Excessive alcohol consumption

Tell your healthcare provider if you are pregnant or plan to become pregnant before taking metformin. If you become pregnant while taking metformin, inform your provider as soon as possible.

Your healthcare provider will help you determine if metformin is right for you. Be sure to be honest about your drinking habits, as alcohol consumption increases your risk of lactic acidosis.

If you experience symptoms of hypoglycemia (very low blood sugar) or lactic acidosis, when taking metformin, contact your healthcare provider immediately. Symptoms include:

• Dizziness, lightheadedness
• Extreme tiredness, weakness, or discomfort
• Confusion
• Coma
• Tremors
• Sweating
• Numbness/tingling
• Nausea, vomiting, stomach pain
• Deep, rapid breathing or shortness of breath
• Fast or slow heartbeat
• Flushing of the skin
• Muscle pain
• Feeling cold, especially in your hands or feet

Other conditions may affect your ability to take metformin. Tell your provider if you have had a serious infection, diarrhea, fever, or vomiting just before or after starting treatment. If you find yourself drinking less fluid for any reason, talk with your provider.

Metformin is generally well-tolerated, but adverse effects can happen. Common side effects of metformin include:

• Diarrhea
• Bloating, gas
• Indigestion, heartburn
• Constipation
• Metallic taste
• Headache
• Changes to the fingernails or toenails

If you experience chest pain or rash when taking metformin, seek emergency treatment. These symptoms could be a sign of an allergic reaction or another serious issue.

Some medications may increase your risk of developing serious side effects if taken with metformin, including: 

• Carbonic anhydrase inhibitors like topiramate (brand name Topamax) and acetazolamide (brand name Diamox)
• Cimetidine (brand name Tagamet)
• Insulin or other medications for diabetes
• Diuretics (water pills)
• Oral steroids such as dexamethasone, methylprednisolone, and prednisone
• Medications for thyroid disease
• Oral contraceptives (birth control pills)
• Hormone replacement therapy
• Calcium channel blockers
• Phenytoin (brand name Dilantin)
• Niacin
• Medications for asthma and colds

Medications not included in these lists may also cause possible interactions. Tell your healthcare provider about all medications, both prescription and over-the-counter, and vitamins or supplements (including herbal supplements) you take before taking metformin.

Metformin is available both generically and under the brand names Fortamet, Glucophage,  Glumetza, and Riomet. It comes in both regular and extended-release formulas. It is also an ingredient in many combination-therapy pills with other diabetes medications. 

Your healthcare provider will determine an appropriate dose. They may choose to start you at a lower amount and gradually increase your dose to reduce the risk of side effects. 

As with all medication, the cost of metformin will be impacted by your healthcare coverage. If the drug isn’t covered by your insurance, metformin still may be affordable. Cost ranges from about $5 to $14 for a thirty-day supply, depending on the dose.

Unfortunately, metformin won’t magically melt away fat. But for people with certain conditions who are unable to meet their weight goals through diet and exercise alone, it could provide an extra boost. If you want to lose weight, talk to your healthcare provider about possible safe and effective treatment plans for you. 

If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

1. Corcoran, C. & Jacobs, T. F. (2020). Metformin. StatPearls. Retrieved Mar. 8 from https://pubmed.ncbi.nlm.nih.gov/30085525/
2. de Silva, V. A., Suraweera, C., Ratnatunga, S. S., et al. (2016). Metformin in prevention and treatment of antipsychotic induced weight gain: A systematic review and meta-analysis. BMC Psychiatry, 16(1), 341. doi: 10.1186/s12888-016-1049-5. Retrieved from https://pubmed.ncbi.nlm.nih.gov/27716110/
3. DailyMed. (2020). Metformin hydrochloride tablet, film coated. Retrieved from https://dailymed. nlm.nih.gov/dailymed/drugInfo.cfm?setid=56d13a1c-b289-4528-b23c-60f5427b4552
4. Diabetes Prevention Program Research Group. (2012). Long-term safety, tolerability, and weight loss associated with metformin in the Diabetes Prevention Program Outcomes Study. Diabetes Care, 35(4), 731–737. doi: 10.2337/dc11-1299. Retrieved from https://pubmed.ncbi.nlm.nih.gov/22442396/ 
5. Dyatlova, N., Tobarran, N. V., Kannan, L., et al. (2022). Metformin associated lactic acidosis (MALA). StatPearls. Retrieved on Mar. 8, 2023 from https://www.ncbi.nlm.nih.gov/books/NBK580485/
6. Fryar, C. D., Carroll, M. D., & Afful, J. (2020). Prevalence of overweight, obesity, and severe obesity among adults aged 20 and over: United States, 1960–1962 through 2017–2018. NCHS Health E-Stats. Retrieved from https://www.cdc.gov/nchs/data/hestat/obesity-adult-17-18/obesity-adult.htm
7. Garvey, W. T., Mechanick, J. I., Brett, E. M., et al. (2016). American association of clinical endocrinologists and American College of Endocrinology comprehensive clinical practice guidelines for medical care of patients with obesity. Endocrine Practice: Official Journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, 22(3), 1–203. doi: 10.4158/EP161365.GL. Retrieved from https://pubmed.ncbi.nlm.nih.gov/27219496/. 
8. Glueck, C. J., Fontaine, R. N., Wang, P., et al. (2001). Metformin reduces weight, centripetal obesity, insulin, leptin, and low-density lipoprotein cholesterol in nondiabetic, morbidly obese subjects with body mass index greater than 30. Metabolism: Clinical and Experimental, 50(7), 856–861. doi: 10.1053/meta.2001.24192. Retrieved from https://pubmed.ncbi.nlm.nih.gov/11436194/
9. Golay, A. (2008). Metformin and body weight. International Journal of Obesity (2005), 32(1), 61–72. doi: 10.1038/sj.ijo.0803695 Retrieved from https://pubmed.ncbi.nlm.nih.gov/17653063/
10. GoodRX. (n.d.) Metformin. Retrieved Mar. 8, 2023 from https://www.goodrx.com/metformin 
11. Mathew, P. & Thoppil, D. (2022). Hypoglycemia. StatPearls. Retrieved on Mar. 8, 2023 from https://www.ncbi.nlm.nih.gov/books/NBK534841/
12. MedlinePlus. (2020). Metformin. Retrieved Mar. 8, 2023 from https://medlineplus.gov/druginfo/meds/a696005.html
13. Yerevanian, A., & Soukas, A. A. (2019). Metformin: Mechanisms in human obesity and weight loss. Current Obesity Reports, 8(2), 156–164. doi: 10.1007/s13679-019-00335-3. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30874963/

Dr. Chimene Richa is a board-certified Ophthalmologist and Senior Medical Writer/Reviewer at Ro.

8 Warning Signs of Type 2 Diabetes

Type 2 diabetes symptoms can be mild and hard to recognize, if they occur at all. It’s easier to spot them if you know what to look for.

By Maria MastersMedically Reviewed by Kacy Church, MD

Reviewed: April 2, 2023

Medically Reviewed

Type 2 diabetes is marked by high blood sugar.

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More than 37 million people in the United States have type 2 diabetes, according to the Centers for Disease Control and Prevention (CDC). But one-fourth of those people don’t know they have the condition.

Getting your annual physical, which typically involves testing your fasting blood sugar levels, is a great first-line screening for type 2 diabetes, no matter how healthy you think your blood sugar levels are, says Dawn Turner, RD, CDCES, a diabetes educator at the Northwestern Medicine Regional Medical Group in suburban Chicago. If your physician finds your levels to be high, they’ll evaluate your A1C, which is a two- to three-month average of your blood sugar levels. In some cases, based on your family history, age, and overall health, your doctor may go ahead and include an A1C test in your yearly workup.

To stay fully on top of your metabolic health, you need to listen to what your body is telling you. Because type 2 diabetes affects every cell in the body, the condition can cause a wide range of symptoms, says Fernando Ovalle, MD, the director of the multidisciplinary diabetes clinic at the University of Alabama at Birmingham School of Medicine. No two people with type 2 diabetes experience the condition in the exact same way, and the number of symptoms and their severity fluctuate from person to person. Dr. Ovalle notes that most symptoms of type 2 diabetes come on and progress gradually.

RELATED: How Is Type 2 Diabetes Diagnosed?

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Frequent Urination Could Be Related to Diabetes

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When there is excess glucose present in the blood, as with type 2 diabetes, the kidneys are not able to handle all of it and have to flush some out of the blood and into the urine, Ovalle says. This results in more urine production and increased urinary frequency and urgency, called polyuria. Some people may notice they have to get up every couple of hours during the night to urinate and that they produce more urine when they do go.

The presence of excess glucose can also cause the urine to have a sweet smell. This is most common in advanced cases of type 2 diabetes, he says.

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Increased Thirst or a Dry Mouth May Signal Diabetes

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Excessive thirst, or polydipsia, is another leading symptom of type 2 diabetes. After all, with increased urination, dehydration can result, according to Mayo Clinic. To try to remedy things, the body uses thirst to urge you to rehydrate.

What’s more, a study from 2017 found that people with type 2 diabetes may produce less saliva, exacerbating feelings of dry mouth, or xerostomia.

RELATED: What Are the Signs of High and Low Blood Sugar?

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Uncontrolled Diabetes May Trigger Unexpected Weight Loss

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In type 2 diabetes, the body’s cells don’t get enough glucose for energy. As a result, the body can turn to breaking down its fat stores for energy, according to the Cleveland Clinic. Severe, unintended weight loss is most common when the type 2 diabetes goes undetected for a long time, according to research.

Increased urination can also contribute to weight loss. For example, if you are urinating high levels of glucose because of uncontrolled diabetes, you are literally flushing calories down the toilet, says Daniel Einhorn, MD, a diabetes specialist in La Jolla, California. Dehydration involves a significant loss of water weight.

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Feeling Hungry All the Time Also May Be a Diabetes Symptom

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In people with type 2 diabetes, the body is not able to use insulin properly to help glucose get into cells. As a result, cells throughout the body can lack the energy they need for proper function. In an attempt to get the cells the energy they need, the body increases feelings of hunger, Turner says.

Excessive hunger, or polyphagia, is a common sign of diabetes. This is different from simply having a desire to eat. Polyphagia happens when you have an appetite even after you have eaten a sufficient amount of food.

RELATED: 20 Quick and Easy Snack Ideas for People With Diabetes

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Foot Pain and Numbness Can Be Signs of Diabetic Neuropathy

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Over time, a prolonged exposure to high blood sugar level can damage the nerves throughout the body through a condition called diabetic neuropathy. Some people may not have any symptoms of the damage, while others may notice numbness, tingling, or pain in the extremities.

“Diabetic neuropathy usually starts in the feet and then it progresses upward,” says Ovalle. Although most common in people who have had type 2 diabetes for 25 years or more, it can occur in people who have prediabetes as well. When it affects the nerves outside the brain and spinal cord, it’s termed peripheral neuropathy.

Numbness in the feet can increase their risk of infection: If you don’t feel a cut or scrape on your foot, you might not notice or properly treat it, he says.

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Frequent Urinary Tract and Yeast Infections Can Signal Diabetes

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Bacteria and yeast multiply more quickly when blood sugar levels are elevated. Excess glucose in the urine, then, can cause urinary tract infections, according to the Cleveland Clinic.

Furthermore, these microbes thrive in warm, moist environments, such as the genital areas. This increases the frequency and severity of yeast infections, especially in women.

RELATED: What Are the Possible Complications of Type 2 Diabetes, and How Can You Avoid Them?

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Blurred Vision Could Be a Result of Rapid Blood Sugar Changes

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Blurred vision can occur when there are rapid changes in blood sugar — from low to high or high to low — and the eye muscles have not yet adapted to it, Dr. Einhorn says.

The lens of the eye is a flexible membrane suspended by muscles that change the shape of the lens to focus the eye. In a high-sugar environment, such as with uncontrolled type 2 diabetes, the lens loses some of its ability to bend, he explains, and the muscles of the eye have to work harder to focus.

The good news: Caught early, diabetes-related vision changes can return to normal after about six weeks of healthy blood sugar levels, Turner says.

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Oral Health Problems Can Point to Diabetes

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Declining oral health is another symptom of type 2 diabetes. “Elevated blood sugar levels can increase the risk of gingivitis, periodontal disease, and inflammation in the mouth,” Turner says. “Any mouth sores can also be slow to heal.”

In fact, in a study published in May 2019, researchers found that people with type 2 diabetes have a higher risk of thick or yellow tongue “fur,” as well as blue-tinged tongues. Researchers note that evaluating tongues is a traditional Chinese practice for diagnosing type 2 diabetes.

RELATED: What Gum Disease Can Mean for Your Overall Health

Most Recent in Type 2 Diabetes

Metformin treatment leads to small but long-term weight loss

New data from the Diabetes Prevention Program Outcomes Study (DPPOS) showed that metformin is associated with “modest but long-term weight loss”, 2% of body weight over 10 years, and appears to be safe and well tolerated.

The results support the findings of the original 3-year double-blind study showing that metformin (850 mg twice daily) resulted in sustained weight loss. In both metformin and placebo groups, weight loss was a strong predictor of diabetes prevention.

According to the Diabetes Prevention Program Research Group, the effect of metformin is similar to exercise.

As previously reported, metformin therapy may represent a more cost-effective alternative to lifestyle changes in the prevention of diabetes.

In the DPP study, overweight and obese participants with impaired glucose tolerance were randomized to lifestyle changes, metformin, or placebo. Results by 2002 showed that metformin therapy resulted in a 31% reduction in the risk of developing diabetes over an average of 2.8 years of follow-up.

During the study, participants randomized to receive metformin had a decrease in body weight and waist circumference compared to placebo patients (mean 2.06% ± 5.65% vs. 0.02% ± 5.52%, and by 2.13 cm ± 7.06 cm versus 0.79 cm ± 6.54 cm, respectively).

During an unblinded follow-up period of 10 years from study entry, weight loss was significantly greater in the metformin group compared with placebo (2. 0% vs. 0.2%) and was associated with the degree of therapeutic compliance.

Participants highly compliant with metformin achieved a weight loss of 3.5% (3.1 kg, 6.8 lb), while those with low compliance experienced initial weight loss, then their weight changed as in the placebo group up to 5 years in which the weight increased.

The authors note that waist circumference increased after 2 years, with the exception of highly compliant participants who experienced an increase after 5 years. Because body weight did not increase, the authors hypothesized that central obesity is related to redistribution of body fat.

“Metformin-induced weight loss was almost exclusively limited to reductions in fat mass with few changes in lean tissue,” the scientists write, emphasizing that caloric restriction leads to loss of both lean and fat tissue.

The authors note that metformin has several effects on energy metabolism similar to exercise, such as phosphorylation of AMP-activated protein kinase, which is an important regulator of mitochondrial biogenetics, fatty acid oxidation in liver and muscle tissue, glucose transport, insulin secretion, and lipogenesis.

During the fourth year of the study, participants who received metformin reported drug-related gastrointestinal symptoms more frequently than those in the placebo group (9.5% vs. 1.1%).

Non-severe hypoglycemia and anemia were relatively rare, with similar rates in the metformin and placebo groups during nearly 18,000 patient-years of follow-up (n = 7 vs. 8 and 50 vs. 38, respectively). Serious adverse events were rare: there were only 3 reports of anemia (metformin, 2; placebo, 1), and no reports of lactic acidosis or hypoglycemia.

During DPP, mean hemoglobin and hematocrit decreased slightly during the first year among metformin-treated participants, but then remained constant (13.6 mg/dl vs 13.8 mg/dl and 40.6% vs 41.1% for both).

Although the proportion of participants with low hemoglobin was similar between groups (11.2% vs. 7.6%), low hematocrit was more common among metformin-treated participants (12.6% vs. 8.4%).

Metformin and weight loss: truth or myth

Losing weight is not an easy task, especially if you need to lose more than a few kilos. There are real drugs that can help you lose weight, but is metformin one of them?

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Weight loss drugs should be used only when there have already been repeated attempts to lose weight for at least six months.

Content of article

What is metformin?

Metformin is a medicine for people with type 2 diabetes mellitus (T2DM). Metformin helps lower blood glucose levels in people who cannot reach their target blood glucose levels through diet and exercise. The American Diabetes Association (ADA) considers it the best first-line diabetes drug for people with type 2 diabetes, starting at age 10.

Metformin may be prescribed off-label for several other purposes:

• gestational diabetes (diabetes diagnosed during pregnancy)
• prevention of type 2 diabetes mellitus (prediabetes)
• polycystic ovary syndrome (PCOS)

fattening. Can he help them? Perhaps a little and only for the first time.

No weight loss drug can replace a healthy, balanced, calorie-deficient diet and physical activity.

Metformin is not registered as a weight loss drug

How does Metformin work?

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The main purpose of metformin is to lower blood glucose levels. This is done by the following mechanisms:

• metformin reduces the production of glucose in the liver
• slows down the absorption of glucose through the intestines
• increases sensitivity to insulin, helping the body to process glucose better

Why does metformin cause weight loss?

The relationship between metformin and weight is unclear, but several theories offer possible explanations for weight fluctuations. According to the Mayo Clinic, reduced hunger is one of the documented side effects of metformin.

In a small 24-week study conducted in 1998, people with diabetes who received metformin lost up to 8 kg due to reduced calorie intake. In a much larger study of over 4,000 people with type 2 diabetes, metformin use was associated with weight loss of 2.4 kg (approximately 5.3 lb) over a four-year period.

Metformin is still not the magic pill, even though there are studies in which metformin shows a clear benefit in weight loss. The amount of weight loss seems to level off over time.

Ways metformin can affect weight:

1. May reduce appetite. This is due to the fact that metformin increases the body’s sensitivity to hormones such as insulin and leptin. Leptin is responsible for the feeling of satiety, so increased sensitivity to this hormone can cause you to feel less hungry.
2. Metformin may increase the secretion of the hormone GLP-1, which suppresses appetite and may cause weight loss. In fact, a GLP-1 receptor agonist drug that specifically targets this hormone, semaglutide, currently exists and has already been approved by the FDA for the treatment of obesity as well as type 2 diabetes.
3. Metformin can also reduce weight by reducing the amount of visceral fat in the liver and muscle tissue. Visceral fat is stored around organs in the abdominal cavity and is a more serious problem than subcutaneous fat.

The word we read over and over in the weight loss studies of metformin is “humble.” It cannot replace important lifestyle changes related to diet and exercise. Weight loss is usually small and may take some time to achieve. Lifestyle changes such as diet and exercise remain the best methods for losing weight.

Is long-term weight loss possible with metformin?

While metformin may help you lose weight, the amount you lose may be much less than expected. According to the Diabetes Care study, the average weight loss after one year of taking the drug is only about 3 kg. Although metformin is often prescribed for people with high insulin levels who find it difficult to lose weight, it is not a weight loss miracle cure.