Does metformin cause weight loss? Our experts weigh in
Metformin is a medication used to manage type 2 diabetes, gestational diabetes, insulin resistance, and polycystic ovary syndrome (PCOS). While it’s not designed for weight loss, some people taking metformin may lose some weight as a side effect.
If your main goal is to lose weight, there are more effective options available—including prescription weight loss injections. If you have a BMI over 35 and a related health condition, you may be eligible for Oviva’s NHS-funded weight loss programme, which includes expert support and access to proven medications like Wegovy.
Key Takeaways
- Metformin is used to treat conditions like diabetes, insulin resistance and PCOS.
- It’s not approved for weight loss but may support it in some people.
- Healthy habits like balanced eating and regular activity are key to long-term weight loss.
- If you have a BMI over 35 and a related health condition, you may be eligible for prescription weight loss medication through Oviva.
What is metformin, and how does it work?
Metformin helps your body respond better to insulin, lowering blood glucose levels. It’s commonly prescribed for:
- Type 2 diabetes – helps control blood sugar and reduces diabetes-related risks.
- PCOS – may help regulate periods and improve ovulation by lowering insulin levels.
- Insulin resistance and gestational diabetes – improves how your body processes glucose.
Metformin comes as tablets, a drinkable liquid, or sachets you dissolve in water.
It has also demonstrated effectiveness in weight loss, even among people without diabetes or PCOS.
Can metformin cause weight loss?
Metformin isn’t approved as a weight loss medication in the UK. But some people taking it experience weight loss, especially when combined with other healthy habits.
How might it work?
Metformin isn’t designed for weight loss, but researchers think it may help in a few different ways:
It may reduce your appetite
A 2024 study found that metformin may increase production of a molecule called Lac-Phe, which is also released after exercise. This molecule is believed to help reduce hunger—meaning you may feel less inclined to eat, which could lead to weight loss over time.
It may help your body burn fat for energy
Metformin lowers insulin levels. Insulin helps your body store and use energy from food. Insulin helps your body use glucose for energy. When insulin levels are reduced, your body uses stored fat to release energy instead, which can help reduce your overall fat levels.
It may help you feel fuller
Metformin may influence how your body produces short-chain fatty acids. Some research suggests short-chain fatty acids can stimulate the release of hormones like GLP-1 and leptin, which can increase feelings of fullness and reduce your appetite
Is metformin an effective weight loss treatment?
Studies show that metformin can produce weight loss results.
One study found that a 1,700 mg/day dose led to a small but sustained average weight loss of 2.5 kg (around 5.5 lbs) over time.
Around 30% of the patients taking metformin achieved body weight loss of more than 5% in the first year.
While overall weight loss was higher among a group in the same study receiving lifestyle interventions, the weight loss in the metformin group was more sustained.
Some people experience no weight loss while taking metformin and even among those who do lose weight, often, the initial weight loss plateaus.
It’s important to stress that metformin alone is not a replacement for healthy weight loss habits.
Metformin should only be taken under medical supervision from healthcare providers.
Who can be prescribed metformin for weight loss?
In the UK, metformin isn’t prescribed for weight loss alone. It may be prescribed if you have:
- Type 2 diabetes
- Gestational diabetes
- Polycystic ovary syndrome (PCOS)
- Insulin resistance
Metformin is often prescribed if you have type 2 diabetes or insulin resistance, and changes to your diet and activity levels haven’t been enough to manage your blood glucose.
Type 2 diabetes and insulin resistance are often linked to weight gain. While metformin isn’t a weight loss medication, it may help with weight management as a secondary benefit.
If you have PCOS, losing just 5% of your body weight can improve symptoms. While metformin may support this, it’s worth exploring other options, like lifestyle changes or weight loss medication with PCOS.
Monitor your goals
Receive personalised recommendations to help you to work towards your goal. Log your food, mood, water intake, exercise and other health metrics using the Oviva app.
Keep a food journal
Snap photos of your daily meals effortlessly within the Oviva app.
Get meal analysis
Get an in-depth meal analysis instantly with a daily summary of your diet.
Stay connected
Connect with your Oviva coach anytime through the app.
Browse learning resources
Written by Oviva’s team of experts, explore advice on nutrition, exercise, and motivation to guide you through the programme and maximise long term weight maintenance.
Who shouldn’t take metformin?
Metformin may not be suitable if you:
- Have kidney or liver problems
- Have poorly controlled diabetes
- Recently had a heart attack or have heart failure
- Have severe breathing or circulation issues
- Drink heavily or regularly
- Have had side effects from metformin before
Always speak to your GP before starting or stopping any medication.
If you’re struggling with weight management, metformin alone isn’t the best option and can’t be prescribed unless you have a relevant health condition.
If you have a BMI over 35, you may be eligible for Oviva’s weight management programme, which can provide tailored support and access to approved weight loss medication.
Metformin vs. weight loss medications
Metformin is not approved as a weight loss medication but may support weight loss. However, other medications are more effective.
Wegovy and Mounjaro are both approved for weight loss in the UK and may be available through the NHS for those who meet certain criteria.
See a comparison of metformin, Wegovy and Mounjaro for weight loss:
| Metformin | Wegovy | Mounjaro | |
| Approved uses | Type 2 diabetes
Gestational diabetes Insulin resistance PCOS |
Weight loss | Type 2 diabetes
Weight loss |
| Recommended dosage | Maximum daily dose of 2,000 mg/day | Starting at 0.25 mg/week
Gradually increasing to 2.4 mg/week |
Starting at 2.5 mg/week
Gradually increasing to 15 mg/week |
| How to take | Tablets
Sachets dissolved in water Liquid |
Self-administered injection, taken once a week. | Self-administered injection, taken once a week. |
| Average weight loss | 2 to 3% of total
body weight after 12 months |
16% of total body weight over 68 weeks | 15 to 21% of total body weight over
72 weeks |
It’s generally safe to take either Wegovy or Mounjaro in combination with metformin, but you should always discuss this with your doctor or diabetes team first.
How to lose weight while taking metformin
You’ll get the most benefit from metformin when it’s combined with sustainable lifestyle changes. Here’s how:
1. Eat well
- Focus on fibre-rich foods and lean proteins to stay fuller for longer.
- Cut back on processed foods, which tend to be high in sugar, salt and unhealthy fats.
- Choose meals that support stable blood sugar and energy levels.
2. Move more
- Exercise can help improve insulin sensitivity.
- It can also help manage gut health—important to minimise side effects.
- Aim for 150 minutes of moderate activity each week (e.g. brisk walking, swimming).
- Add resistance exercises to help maintain muscle.
- Daily movement—like housework or gardening—counts too.
- You may need to gradually build towards this over time.
3. Track your progress
- Use a journal or app to log meals, mood, exercise, and weight.
- Tracking helps you notice patterns and stay motivated.
One study found that people who logged their food most days lost weight faster and more sustainably than those who didn’t.
4. Prioritise sleep
- Aim for 7–9 hours of sleep a night, if you can.
- Sleep helps boost your metabolism and supports appetite regulation and energy.
- A regular bedtime can help, but even small changes matter.
- Getting enough exercise and managing stress can also help to improve your sleep.
5. Weight loss medications
If you meet the eligibility criteria, you may be able to combine metformin with approved weight loss medications like Wegovy or Mounjaro. Always speak to your doctor or diabetes team first to ensure this approach suits you.
How Oviva can support your weight loss journey
Oviva is your personalised, NHS-funded weight loss plan for long-term results.
No calorie counting. No crash diets. Just expert, one-to-one support from dietitians and doctors who get it — plus a simple-to-use app that fits around your life.
Whether you’re managing type 2 diabetes, PCOS, or struggling to lose weight on your own, Oviva gives you the tools, the structure, and the accountability to make real, lasting change.
Sick of quick fixes that don’t stick? This is where you turn things around.
Trust the 97% of Oviva users that would recommend us.
-
Weight management -
Weight management
