Metformin Weight Loss: Does This Drug Help You Lose Weight 2024?

metformin weight loss
Metformin may potentially help with weight loss efforts. Photo: Who is Danny/Shutterstock

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Weight loss can be a confusing task for many people. Several articles online about weight loss answer questions such as “How much cardio should you do to lose weight?” and “How long does it take to lose weight?”

People are often told what foods to avoid and what exercises correlate most to weight loss. What most related articles don’t seem to mention is how the antidiabetic drug metformin is linked to a decrease in body mass index and overall body weight.

In recent years, it has become a subject of fascination for some researchers looking for how to lose weight fast on metformin. Although metformin wasn’t designed to be a weight loss drug and metformin weight loss reviews appear to be scarce, it could still be a helpful tool.

So, can metformin cause weight loss, and how long would it take to lose weight by taking metformin?

Does Metformin Cause Weight Loss?

Yes, metformin can cause very minor weight loss for some people. However, metformin is not a weight loss drug, and methods such as a healthy hypocaloric diet and regular exercise are much more effective for weight loss.

Metformin Weight Loss

metformin weight loss
Metformin may promote minor weight loss results. Photo: Sonis Photography/Shutterstock

First of all, what is metformin?

Metformin is an antidiabetic agent[1] that helps to control the amount of glucose in your blood, simply known as your blood sugar. It does this by[2] decreasing its production in the liver to reduce intestinal absorption while enhancing insulin sensitivity. Metformin treatment is also given to those who have[3] polycystic ovary syndrome or PCOS to reduce androgen levels to normal, prevent diabetes, and lose weight.

Those with type 2 diabetes can take metformin either by itself or in combination with other antidiabetic drugs such as insulin medications. In fact, it can be used as a way to treat prediabetes and even prevent type 2 diabetes or gestational diabetes altogether.

So, for those wondering, “Is metformin used for weight loss?” the answer is not exactly. It is not designed to be a weight-loss drug. Its main purpose is for glycemic control and to increase insulin sensitivity in patients who have diabetes.

Although type 2 diabetes and insulin resistance are not directly linked to weight gain or human obesity, taking metformin and weight loss do seem to have some sort of correlation based on science. The cardiometabolic effects of metformin have been found to decrease body mass index, BMI, and overall body weight in some people.

In fact, some people have discovered that taking metformin can help address antipsychotic-induced weight gain, which is caused by antipsychotics such as clozapine and olanzapine, which alter glucose metabolism in a way that increases body mass index and the risk for type 2 diabetes. Using metformin alongside antipsychotics[4] can counteract this interaction and reduce weight gain from the latter.

Why Does Metformin Cause Weight Loss

With all of that said, how exactly does metformin help with weight loss?

Metformin is known as a weight-neutral drug, though it is possible for taking it to cause a small amount of weight loss based on scientific evidence. So, at the very least, even if the evidence to support claims of it helping with weight loss isn’t concrete, taking metformin won’t make you gain weight in most cases. Metformin may cause a decrease in appetite or intake of food[5] from gut-related changes in appetite hormones, or GI side effects that affect food intake.

Any possible weight loss that comes from taking this drug may be because metformin decreases food consumption. The increase in sensitivity to insulin[6] can lead to a reduced appetite in some patients, meaning that they’ll find it easier to cut back on eating certain foods and resist cravings that may cause them to gain weight.

Weight Loss Studies Explained

In one study, researchers examined how metformin therapy influences metabolic parameters in those at high risk of developing type 2 diabetes. In terms of weight loss, participants who were randomly assigned to the experimental group taking metformin lost an average of 2.1 kg of body weight,[5] as well as an average of 3.5% reduction in overall body mass. Furthermore, those who were assigned to the experimental group also noticed more of a decrease in waist circumference compared to that of the control group.

For those hoping that taking metformin is one potential answer for losing weight fast without exercise, don’t expect metformin to be some magic pill to get slimmer overnight. The results of follow-up studies to support the Diabetes Prevention Program outcomes mentioned previously are so insignificant and inconsistent that the FDA has not approved metformin being used as a weight loss drug. Realistically, metformin can only be considered a supplement to long-term lifestyle changes that promote weight loss, such as exercising and eating a healthy diet.

As for how much weight you’ll lose on metformin, it’s hard to say.

The rate at which your body burns fat and loses weight, along with where fat will be burned on your body, depends not only on your life choices but also on your genetics. You have no control over what genes you are born with, and no amount of metformin — or any medication, for that matter — can change that.

Metformin Dosage For Weight Loss

As for how much metformin to lose weight, it depends primarily on age.

According to researchers and other health experts, the ideal dosage[7] of metformin for weight loss is 3,000 milligrams per day for adults, as long as it is paired with some lifestyle modifications that promote weight loss. The ideal metformin weight loss dosage in adolescents is 1,000 mg per day over the course of 90 days, though metformin in 500 mg for weight loss appears to also be a viable option in case their bodies can’t handle 1,000.

Regardless of the dosage, it is recommended to start on a lower dose to reduce the chance of experiencing any unwanted side effects. From there, your doctor can gradually increase the dosage every few weeks.

Metformin Side Effects

metformin weight loss
Metformin usage comes with a risk of side effects. Photo: max.ku/Shutterstock

Like all medications, Metformin can cause various side effects[1] regardless of why you’re taking it. Before starting on metformin for weight loss, it is important to seek consultation from a doctor or other healthcare provider first to make sure it is safe and appropriate for you to take. Your doctor can also warn you of any potential precautions to take while on metformin to reduce the likelihood of adverse reactions.

Some potential side effects of this drug include, but are not limited to, the following:

Abdominal Pain

Gastrointestinal or GI side effects are the most common ones associated with metformin.

Some patients with diabetes who are on metformin may experience some form of abdominal pain that is often accompanied by other GI-related symptoms such as gassiness, diarrhea, indigestion, constipation, or a bloated feeling. This may seem very similar to those who know how to eat flax seeds for weight loss, which can cause similar feelings of being bloated.

The best way to reduce the likelihood and/or intensity of GI side effects from metformin is by starting off with a low dose and taking metformin with food.


While taking metformin, it is important to monitor your blood sugar levels. This is because since the main purpose of metformin is to decrease glucose production and build up in your bloodstream, you want to have a high degree of blood sugar control.

Hypoglycemia occurs when your blood sugar levels are very low. However, it is unlikely that you will experience low blood sugar reactions on metformin unless combined with insulin or other diabetes medications.

In the event you develop hypoglycemia, the fastest way to find relief is by eating a small snack of about 15 grams of carbohydrates or less. Those who intend to use metformin as a weight loss agent have to remember how many carbs per day they should be consuming.

Thus, it is imperative in such cases to know how to calculate net carbs so you can find a snack that doesn’t impact your carb or overall food intake too much. To do this, you need to subtract the number of grams of sugar, alcohol, and fiber from the overall number of grams of carbs.

If you’re looking to treat the headaches that can come from hypoglycemia, then it is also highly recommended to drink water to find some relief.


When used over a long period of time, spanning several months or even years, metformin can lead to an eventual vitamin B12 deficiency,[8] especially when taken at larger doses. This can lead to feelings of moderate to severe fatigue or a lack of energy accompanied by feelings of faintness and breathlessness.  

Fortunately, it is very easy to relieve these symptoms by simply increasing the amount of vitamin B12 you consume. Some foods that can be eaten to treat vitamin B12 deficiency while still promoting weight loss include dairy products, various types of meats, including beef and chicken, and certain types of fish, such as salmon or tuna. Some herbs for weight loss, such as dandelion and garlic, can also give your body a slight boost in vitamin B12 if added to your diet.

The real at-risk groups for B12 deficiency when taking metformin for modest weight reductions are vegans and vegetarians. They must typically take a B12 supplement.

Lactic Acidosis

Supposedly, the most serious adverse reaction that you could experience while taking metformin is lactic acidosis or a buildup of lactic acid in your bloodstream. This condition can reduce cardiac contractility, which can cause nausea and fatigue at best and be life-threatening at worst.

Fortunately, this rarely occurs, though the likelihood of this happening comes from whether or not the patient has certain cardiovascular or kidney-related issues. Its risk also increases[9] in those following a keto diet.


It is important to note that metformin is, first and foremost, an antidiabetic drug for treating issues with insulin resistance associated with type 2 diabetes. Any impact it appears to have on weight loss is almost exclusively secondary; it should not be considered an actual weight loss drug.

Even though the evidence isn’t concrete, it still has the potential to help you lose even just a few pounds if used as a sort of supplement to weight loss. Any weight loss can be considered crucial, so metformin is still worth considering even if you don’t have diabetes.

Metformin is no miracle pill. Between metformin or lifestyle interventions that include cutting out unhealthy eating habits or promoting more physical activity, the latter is more effective.

If you do plan on using metformin as a weight loss agent, be sure to check with your primary healthcare provider first to see if it’s appropriate for you to take. Everybody’s body will react differently to the drug, so your doctor can guide you through special precautions.

Frequently Asked Questions

What is the average weight loss with metformin?

When taking metformin, people can lose an average of only four to six pounds over the course of several months of long-term use, typically after at least six months.

How quickly will you lose weight on metformin?

If you use metformin as a way to promote weight loss in your body, you can see results after at least six months. That is to say, two months of metformin weight loss results will barely be noticeable.

Can I take metformin to lose weight if I’m not diabetic?

It is typically not recommended for people without diabetes or PCOS to use metformin for weight loss. However, that does not mean it is necessarily harmful to those who don’t have type 2 diabetes or PCOS.

What not to eat on metformin?

If you’re taking metformin for weight loss, you should avoid foods high in fats or sugar, as these can lead to mild GI side effects or exacerbate the issue, and combine the drug with healthy eating.

How to maximize weight loss on metformin?

Weight loss on metformin works best when combined with a balanced, hypocaloric diet and a sufficient amount of weekly exercise that helps burn away body fat.

+ 9 Sources

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  1. (2020). Metformin: MedlinePlus Drug Information. [online] Available at:
  2. Nasri, H. and Rafieian-Kopaei, M. (2014). Metformin: Current knowledge. Journal of research in medical sciences : the official journal of Isfahan University of Medical Sciences, [online] 19(7), pp.658–64. Available at:,the%20intestines%20or%20stomach%20absorb.
  3. Hany Lashen (2010). Review: Role of metformin in the management of polycystic ovary syndrome. Therapeutic Advances in Endocrinology and Metabolism, [online] 1(3), pp.117–128. doi:
  4. Hakami, A.Y., Razaz Felemban, Rami Ghazi Ahmad, Abdulrahman Hamid Alsamadani, Salamatullah, H.K., Baljoon, J.M., Alghamdi, L.J., Mostafa and Mohamed Eldigire Ahmed (2022). The Association Between Antipsychotics and Weight Gain and the Potential Role of Metformin Concomitant Use: A Retrospective Cohort Study. Frontiers in Psychiatry, [online] 13. doi:
  5. Armen Yerevanian and Soukas, A.A. (2019). Metformin: Mechanisms in Human Obesity and Weight Loss. Current Obesity Reports, [online] 8(2), pp.156–164. doi:
  6. Cree‐Green, M., Bergman, B.C., Cengiz, E., Fox, L.A., Hannon, T.S., Miller, K.M., Nathan, B.M., Pyle, L., Kahn, D.E., Tansey, M., Tichy, E., Tsalikian, E., Libman, I. and Nadeau, K.J. (2019). Metformin Improves Peripheral Insulin Sensitivity in Youth With Type 1 Diabetes. The Journal of Clinical Endocrinology and Metabolism, [online] 104(8), pp.3265–3278. doi:
  7. Hui, F., Zhang, Y., Ren, T., Li, X., Zhao, M. and Zhao, Q. (2018). Role of metformin in overweight and obese people without diabetes: a systematic review and network meta-analysis. European Journal of Clinical Pharmacology, [online] 75(4), pp.437–450. doi:
  8. Kim, J., Ahn, C.W., Fang, S., Lee, H.S. and Park, J.S. (2019). Association between metformin dose and vitamin B12 deficiency in patients with type 2 diabetes. Medicine, [online] 98(46), p.e17918. doi:
  9. Aryadi Arsyad, Idris, I., Rasyid, A.A., Usman, R.A., Faradillah, K.R., Wa, Zidni Imanurrohmah Lubis, Aminuddin Aminuddin, Ika Yustisia and Yulia Yusrini Djabir (2020). Long-Term Ketogenic Diet Induces Metabolic Acidosis, Anemia, and Oxidative Stress in Healthy Wistar Rats. Journal of Nutrition and Metabolism, [online] 2020, pp.1–7. doi:


Christine is a certified personal trainer and nutritionist with an undergraduate degree from Missouri State University. Her passion is helping others learn how strong and healthy they can become by transforming their daily habits. Christine spends… See More