Can Metformin Cause Weight Loss?

Weight loss pills are usually too good to be true. 

If an effective weight loss pill existed, then there wouldn’t be thousands of weight loss books published or hundreds of diet programs invented over the past several decades.

Metformin is one of the most popular medications to treat type 2 diabetes. While metformin isn’t specifically meant for weight loss, it might promote weight loss as one of its potential side effects. 

Metformin can be especially beneficial if you have insulin resistance, existing type 2 diabetes or prediabetes, and are overweight or obese.

Does metformin cause weight loss?

Metformin isn’t considered a weight-loss drug, but it has been shown to produce modest weight loss among some people who take it. 

According to a study on non-diabetic individuals with a body mass index (BMI) over 27, taking metformin resulted in more weight loss than the control group.

According to that study, metformin was more effective in producing weight loss when the participants were considered “severely” insulin-resistant compared to insulin-sensitive patients. 

The group receiving up to 2,500 milligrams of metformin daily for six months lost an average of nearly 13 pounds, while the group that didn’t receive metformin gained weight on average.

A review of over 30 clinical trials summarized that taking metformin significantly reduced both weight and BMI. Researchers noted that 2,000 milligrams per day could be suitable for adolescents, while doses of 1,000 milligrams or 3,000 milligrams daily were the most effective for metformin weight loss.

How does metformin help you lose weight?

Part of the reason metformin is believed to aid in weight loss is through suppressing your appetite and reducing your caloric intake. If you eat fewer calories than you normally do without changing your activity level, weight loss can occur. 

As this study found, taking metformin resulted in lower caloric intake among obese participants with type 2 diabetes.

Metformin comes with potential negative side effects such as bloating, gas, diarrhea, belly pain, and reduced appetite. These side effects may play a part in reducing your appetite and inducing weight loss as well.

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What dosage of metformin causes weight loss?

The common dosage for metformin when treating type 2 diabetes ranges from 500 milligrams to a maximum of 2,550 milligrams per day. It’s usually recommended to split the dose among meals, typically three times per day. 

According to the studies we mentioned earlier, the metformin dosage for weight loss ranged from 1,000-2,500 milligrams daily. Because metformin isn’t meant to be used solely as a weight-loss drug, there isn’t a standard recommendation for dosing for that purpose.

If your healthcare provider recommends metformin, they will prescribe a dosage appropriate for your body composition, health history, and current blood test results. You might start with a lower dose and increase it over time.

When is the best time to take metformin?

There are two types of metformin – regular and extended-release (XR). The extended-release version of metformin is meant to be taken once daily, usually with breakfast or dinner.

If you take regular metformin, it’s recommended to split your dose evenly among your meals. Metformin tablets are usually 500 or 850 milligrams each. A standard starting dose is to take one 500 milligram tablet twice daily with meals and increase as tolerated over a few weeks until you reach the goal dose.

The best time to take metformin for weight loss is when you will remember and therefore be able to take it most consistently. You should avoid taking a full dose all at once to reduce potential negative side effects, though.

How long after starting metformin do people tend to experience weight loss?

The studies on metformin and weight loss were typically within a six-month time frame. Everyone loses weight at different rates, so it’s impossible to predict when you might notice weight loss from taking metformin.

Gastrointestinal side effects are usually the worst when you first start taking metformin. Side effects often get better as your body gets used to the medication. If you lose weight because of the side effects of metformin, you may notice the most significant weight loss within a few weeks of starting metformin.

Is metformin effective as a weight loss pill? 

Metformin isn’t meant to be used solely as a weight-loss drug. However, you might experience weight loss as a result of taking metformin. As mentioned earlier, several scientific studies suggest that metformin may be effective in promoting weight loss, especially among those with obesity.

Metformin can be used off-label, which is when it’s prescribed for reasons other than what the FDA has approved it to treat. For instance, metformin is used off-label in some women with polycystic ovarian syndrome and related infertility. If metformin is prescribed solely as a weight-loss drug, it is being used off-label.

Metformin helps reduce fat accumulation in muscle tissue by increasing fat oxidation, which essentially means metabolizing fats into usable energy. The exact way metformin helps boost fat oxidation isn’t entirely clear, but it is one of the reasons why metformin may be beneficial for weight loss.

What are the potential adverse effects of metformin?

One of the potential benefits of metformin over other weight loss pills is that there are minimal serious adverse effects. Metformin doesn’t cause low blood sugar, so it’s safe to use even in people who don’t have diabetes.

Some weight-loss drugs and supplements are dangerous, such as Ephedra. Ephedra was a popular weight loss aid in the 1990s and early 2000s that the FDA later banned since it caused heart rhythm irregularities, heart attack, stroke, seizure, and sudden death.

While rare, metformin’s main serious adverse effect is lactic acidosis. Lactic acidosis is a serious condition where your body creates more lactic acid than your body can clear. The symptoms of lactic acidosis usually set in quickly and include:

  • Abdominal or stomach discomfort
  • Decreased appetite
  • Diarrhea
  • Fast, shallow breathing
  • Discomfort
  • Muscle pain or cramping
  • Unusual sleepiness, tiredness, or weakness

Metformin overdose is the main risk factor for developing lactic acidosis. According to a position statement in the American Diabetes Association’s Diabetes Care, “When metformin is used as labeled, the increased risk of lactic acidosis is either zero or…close to zero.”

If you have severe kidney disease, you might also be at greater risk of developing lactic acidosis because your kidneys can’t clear the lactic acid from your system, so that could make you a poor candidate for taking metformin. 

Metformin is safe to use when the estimated glomerular filtration rate (GFR) is greater than or equal to 45 milliliters per minute. The GFR is an indicator of how efficiently your kidneys filter blood. A GFR greater than 60 mL/minute is considered normal, and kidney failure occurs when the GFR falls below 15.

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Will your doctor prescribe metformin for weight loss?

Whether or not your doctor prescribes metformin for weight loss will depend on many factors, so it’s truly a unique situation for everyone.

Your doctor might be more likely to prescribe metformin for weight loss if you have prediabetes, a condition that increases your risk of developing type 2 diabetes later in life. 

They might be more inclined to prescribe metformin for weight loss if you have one or more of the common risk factors for type 2 diabetes, such as if you:

  • Are overweight or obese
  • Are age 45 or older
  • Have a family history of diabetes
  • Are African American, Alaska Native, Native American, Asian American, Hispanic/Latino, Native Hawaiian, or Pacific Islander
  • Have a low level of HDL (“good”) cholesterol or a high level of triglycerides
  • Have a history of gestational diabetes or gave birth to a baby weighing 9 pounds or more
  • Are not physically active
  • Have depression
  • History of heart disease or stroke
  • Have polycystic ovary syndrome (PCOS)
  • Have acanthosis nigricans (dark, thick, and velvety skin around your neck or armpits)

Can metformin cause weight gain?

Metformin isn’t likely to cause weight gain on its own. Instead, metformin is considered a drug that can help promote weight loss, especially if you are overweight, obese, and/or have insulin resistance.

Metformin helps lower blood sugar levels by making your body more sensitive to insulin. Insulin resistance is a common condition that can lead to the development of type 2 diabetes. 

Insulin is a hormone that helps lower blood glucose (blood sugar) levels. It also helps promote the storage of fat. If you have insulin resistance, your body doesn’t respond to insulin effectively, which can lead to higher blood sugar levels.

Once your blood sugar levels start to rise, your body will try to compensate by producing more insulin. This process continues, which can lead to more fat storage and accumulation and weight gain.

Since metformin helps improve insulin sensitivity, it’s unlikely to cause weight gain. If you change your lifestyle habits, such as your food intake or activity level, once you start taking metformin, then you could gain weight because of those other factors.

How weight loss can help you manage your diabetes

Weight loss can significantly improve your blood sugar control. Weight loss is so effective at improving blood sugar levels and insulin sensitivity that it’s the primary goal for the nationally accredited Diabetes Prevention Program (DPP). The purpose of DPPs is for patients to lose at least 7% of their starting body weight.

Lifestyle interventions that result in weight loss can reduce the incidence of type 2 diabetes by almost 60%. According to the National Institute of Diabetes and Digestive and Kidney Diseases, another potential benefit of taking metformin is improved cardiovascular health through promoting healthy cholesterol and blood pressure.

According to a study, patients’ A1c levels dropped by 0.1% for every one kilogram of body weight lost. (The hemoglobin A1c is a more accurate indicator of overall blood sugar control since it’s a 60-90 day running average of your blood glucose.)

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Other ways to lose weight while taking metformin

Healthy lifestyle changes, in addition to taking metformin, can provide the best results in terms of weight loss. If you’re prescribed metformin for your diabetes, it’s best not to rely completely on it for blood sugar control and potential weight loss benefits. 

Some people can stop taking medications for their diabetes if their blood sugar improves enough through healthy lifestyle changes alone.

If you’re looking for some healthy ways to lose weight in addition to taking metformin, here are some great ideas that will also benefit your health.

Cut back on added sugar

Added sugar contributes a significant amount of additional calories to your diet. Added sugar is any type of sugar that isn’t naturally present in a food or drink.

Sugary beverages like soda, sweetened coffee, and many other drinks are the leading source of added sugar in the typical Western diet. Added sugar can also be hidden in foods that seem healthy, like whole-wheat bread, yogurt, and many types of cereal.

The American Heart Association recommends limiting your added sugar intake to fewer than 36 grams of added sugar per day. For a frame of reference, one 12-ounce can of standard Cola contains 39 grams of added sugar, which is already over 100% of the recommendation.

To spot added sugar, you’ll need to look at the nutrition facts and ingredients labels on packaged foods you buy. The good news is that whole, unprocessed foods don’t have added sugar, so you don’t have to worry about added sugar with fresh fruit, vegetables, meat, legumes, and plain dairy products, to name a few examples.

Show fiber some love

Dietary fiber, also known as roughage or bulk, comes from parts of plant foods your body can’t digest and absorb. Fiber helps make you feel full since it takes longer for your stomach to digest than some lower-fiber foods. Including fiber in your meals and snacks is one method to aid in healthy weight loss.

Fiber is only found in plant foods but can also be added to non-plant foods to increase their fiber content. Animal products don’t contain fiber, such as meat and dairy products.

Plant-based foods vary in their fiber content based on their type and how much they’ve been processed. For instance, a whole apple has more fiber than applesauce because the fruit isn’t broken down from its original state and maintains the skin.

Fiber is also found in wheat products, but its amount is dependent on the type of product. 100% whole grain products maintain most of their fiber content because the bran and germ are maintained instead of being removed like they are in refined grain products. 

Some examples of high-fiber foods include:

  • Raspberries
  • Pears
  • Apples
  • Bananas
  • Oranges
  • Strawberries
  • Green peas
  • Broccoli
  • Turnip greens
  • Brussels sprouts
  • Potatoes
  • Cauliflower
  • Carrots
  • Barley
  • Bran flakes
  • Quinoa
  • Oat bran 
  • Oatmeal
  • Air-popped popcorn
  • Brown rice
  • Whole wheat bread 
  • Split peas
  • Lentils
  • Black beans
  • Chia seeds
  • Almonds 
  • Pistachios
  • Sunflower kernels

Not only can fiber help you achieve healthy weight loss, but it’s good for your digestive and heart health as well.

Get moving

Physical activity plays a major role in losing weight. However, most people fall short of the recommendation to get 150 minutes of physical activity per week. Physical inactivity can lead to weight gain and health problems like heart disease.

To achieve sustainable weight loss, it’s best to find something you enjoy. You don’t have to spend hours of your day at a gym or hire a personal trainer to benefit from exercise.

If you have a busy schedule, aim to get your physical activity in three ten-minute segments. A ten-minute walk in the morning before work, a ten-minute walk during your lunch break, and a ten-minute walk after dinner will easily satisfy the 30 minutes per day goal.

Get enough sleep

Sleep deprivation can worsen insulin resistance, which can lead to high blood sugar levels and weight gain. Setting a bedtime routine, having a consistent wake-up time, avoiding caffeine later in the day, and getting regular physical activity during the day can help promote healthy sleep patterns.

What if you’re worried about your weight loss?

Metformin shouldn’t cause drastic weight loss. If you’re losing weight quickly, especially if you haven’t been trying, you should consult your healthcare provider for an evaluation. 

Losing 5-10% of your body weight in a year can be a red flag if you didn’t lose weight through healthy lifestyle changes or other intentional habits.

If you’re losing too much weight on metformin due to adverse side effects (stomach issues, diarrhea, bloating, etc.), then you should speak with your healthcare provider.


Metformin is considered a safe and effective medication to treat type 2 diabetes. It may also help you lose a modest amount of weight, which can further improve insulin sensitivity and blood glucose levels.

Metformin isn’t considered a weight-loss drug, but some healthcare providers may prescribe it to patients at risk of developing type 2 diabetes and who also want to pursue weight loss.

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Metformin Diet: 5 Foods To Eat and 6 You Should Avoid.


  1. Seifarth C, Schehler B, Schneider HJ. Effectiveness of metformin on weight loss in non-diabetic individuals with obesity. Exp Clin Endocrinol Diabetes. 2013. 
  2. Hui F, Zhang Y, Ren T, Li X, Zhao M, Zhao Q. Role of metformin in overweight and obese people without diabetes: a systematic review and network meta-analysis. Eur J Clin Pharmacol. 2019.
  3. Lee A, Morley JE. Metformin decreases food consumption and induces weight loss in subjects with obesity with type II non-insulin-dependent diabetes. Obes Res. 1998.
  4. Wang C, Liu F, Yuan Y, Wu J, Wang H, Zhang L, Hu P, Li Z, Li Q, Ye J. Metformin suppresses lipid accumulation in skeletal muscle by promoting fatty acid oxidation. Clin Lab. 2014.
  5. Zell-Kanter, M., Quigley, M., & Leikin, J. (2015). Reduction in Ephedra Poisonings after FDA Ban. New England Journal Of Medicine, 372(22), 2172-2174. 
  6. Misbin, Robert. The Phantom of Lactic Acidosis due to Metformin in Patients With Diabetes (2004) 
  7. Hur KY, Kim MK, Ko SH, et al. Metformin Treatment for Patients with Diabetes and Chronic Kidney Disease: A Korean Diabetes Association and Korean Society of Nephrology Consensus Statement. Diabetes Metab J. 2020.
  8. Gummesson A, Nyman E, Knutsson M, Karpefors M. Effect of weight reduction on glycated haemoglobin in weight loss trials in patients with type 2 diabetes. Diabetes Obes Metab. 2017.

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