Many medications prescribed for patients with type 2 diabetes have been found to help with weight loss, such as Saxenda and Wegovy. As well as managing blood sugar, metformin is another medication proven to achieve weight loss but has yet to be approved as a weight loss medication.

Below we look at metformin in more detail and answer the common questions regarding metformin, such as does metformin cause weight loss?

What is Metformin?

Metformin was originally one of the first medications used to treat type 2 diabetes when a healthy diet and exercise program could not control a patient’s blood sugar (blood glucose) levels. It is a man-made treatment based on a compound found in the French lilac plant.

Metformin belongs to a group of medications called biguanides. In overweight adults, it can also lower the risk of complications caused by diabetes. Metformin is a tablet that is taken up to three times a day, with or after a meal. If you have diabetes, you may also be prescribed insulin.

How Does Metformin Work?

Insulin is an important hormone produced in the pancreas that controls blood sugar levels. This can also affect your weight. When you eat, insulin removes glucose from your blood and either stores it for later or uses it to produce energy.

This energy can be used for everyday functions, such as creating new cells or breathing. Your body may need more energy and is less likely to store glucose if you are working out or doing lots of physical activity during the day.

If you have type 2 diabetes, your pancreas cannot make enough insulin, or your body cannot use insulin properly. This causes a high level of glucose in your bloodstream. Metformin is used to lower blood glucose levels to normal limits. It has also been found to help patients lose weight and improve weight management.

How Does Metformin Cause Weight Loss?

Metformin is still being tested for weight loss, but there are a few solid theories as to why it helps with losing weight.

Promoting insulin sensitivity

The exact reason that metformin causes weight loss is unknown, but it likely has something to do with blood sugar levels. When we have excess glucose in our blood, this signals our body to store it. Glucose is stored in our muscles and liver.

When these are full, glucose is stored as fat, which causes weight gain. If you have poor insulin sensitivity, you may take up more glucose than you need, meaning more fat stores.

As metformin helps to lower blood glucose levels, it can limit the amount of fat we store, helping us to lose weight and improve insulin sensitivity.

Boosting appetite-suppressing hormones

Metformin has also been proven to make you feel less hungry, much like other diabetic medications. It can increase the secretion of GLP-1 (Glucagon-like peptide-1). This is a hormone released after eating, which sends signals to your appetite centre in the brain.

Basically, metformin tells your brain “I’m full”, making it easier to reduce your calorie intake without

Changing your gut microbiome

Metformin may affect your gut microbiome, including an increase in the production of SCFAs (short-chain fatty acids). SCFAs have been linked to better insulin sensitivity and improved appetite regulation.

Battling ‘inflammaging’

Metformin is thought to combat inflammation linked to human obesity, which is diagnosed by calculating your BMI (body mass index). In particular, it is thought to help with low-grade systemic inflammation, which has been termed as ‘inflammaging’.

How Much Weight Can You Lose on Metformin?

Although metformin can aid with weight loss, it is not the most potent weight loss treatment available. Weight loss can vary from person to person, depending on age, insulin sensitivity, diet, and lifestyle.

In one study from 2019, patients taking metformin lost around 5% of their original body weight in the first year of treatment.

In comparison to other approved weight loss medications such as Saxenda, your doctor will look for a 5% initial body weight loss within the first 12 weeks.

That being said, metformin can still help with weight loss and lower the risk of type 2 diabetes, but it is not a ‘miracle weight loss drug’.

How Fast Will You Lose Weight on Metformin?

Again, this depends on your diet and lifestyle changes, but weight loss can be expected anywhere from 6 to 12 months of use. Patients may see weight loss earlier if they have a high body fat percentage and poor insulin sensitivity.

Can People Without Diabetes Take Metformin for Weight Loss?

Metformin is available for weight loss in patients who are overweight or obese and are at risk of type 2 diabetes or have prediabetes. This is known as ‘off-label’ use, which means doctors can prescribe metformin if they think it is suitable.

Metformin for Weight Loss Dosage

Metformin is often started at a lower dose and gradually increased to get the best effects from the medication with a lower risk of side effects. The exact dosage for weight loss is unknown as metformin is not yet approved as a weight loss treatment.

If you are given metformin for weight loss, your doctor will prescribe the correct dose for you.

Side Effects and Precautions

Metformin can cause some side effects, which is why the dosage is increased slowly. The most common side effects are:

● nausea

● vomiting

● diarrhoea

Common side effects of metformin also include:

● constipation

● headaches

● bloating

● stomach pain

● heartburn or indigestion

● an unpleasant taste

There are also some serious side effects you should look out for, such as hypoglycemia (low blood sugar levels).

In extremely rare cases, metformin can cause lactic acidosis, which is a medical emergency caused by too much metformin. Symptoms of lactic acidosis include confusion, appetite loss, muscle pains, dizziness, and trouble breathing.

You should not take metformin if you have low blood sugar or if you take certain medications, such as aspirin.

Healthy Weight Loss

Effective weight loss can be achieved through a weight loss plan, which consists of a healthy diet and exercise regime. If you are struggling to lose weight, there are approved weight loss treatments available in the UK to help you achieve healthy weight loss and maintaining weight loss. Speak to your healthcare provider for more information.

Metformin and other FDA approved diabetes medications can help with weight loss, especially in patients with poor insulin sensitivity. The best weight loss results are seen with long-term use. You can only use metformin for weight loss if it has been prescribed to you.

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.