Metformin for PCOS: how it works, benefits and weight loss
If you’re living with PCOS, managing weight, cravings or energy can feel harder than it should. That’s partly because PCOS is often linked with insulin resistance – where the body struggles to use insulin properly, leading to higher insulin levels and weight gain.
Metformin is sometimes prescribed off label to help improve insulin response and ease symptoms. It may also support weight loss for some.
Oviva offers an NHS-funded weight management programme for people with a BMI over 35 and conditions like PCOS – including a personalised plan, 1:1 coaching and, if suitable, prescription medication.
Key Takeaways
- Metformin is sometimes prescribed off-label to treat PCOS.
- It may help by improving insulin resistance, which affects up to 80% of people with PCOS.
- Metformin can regulate your period, support ovulation and lower the risk of miscarriage.
Metformin for PCOS – how it works
While metformin is typically prescribed for type 2 diabetes, it can support people living with PCOS by dealing with insulin resistance. It’s not a licensed PCOS medication, but is sometimes used ‘off label’.
Let’s quickly cover what insulin resistance is
- Insulin’s job is to move glucose from your blood into your cells for energy
- With insulin resistance, your cells don’t respond properly to insulin
- Your body makes more insulin to try to fix this, but your cells remain resistant and don’t take in the glucose
- Glucose stays in the blood and is stored as fat
- Because glucose isn’t getting into cells, you may feel tired and hungry
- This can lead to strong cravings, especially for sugary foods
- The extra insulin in your body signals to your ovaries to produce more androgens (like testosterone) which can disrupt your menstrual cycle, cause excess hair growth and acne
Up to 80% of women with PCOS have insulin resistance – it can help explain some of the most common symptoms of PCOS:
- Low energy levels
- Weight gain
- Irregular or missing periods
- Excess hair
- Acne
Metformin improves the way your body handles insulin. So, if you have PCOS, taking metformin can help you manage those common symptoms that can be caused by high levels of insulin.
Metformin can regulate your menstrual cycle, boost fertility and improve metabolic symptoms that cause weight gain.
Benefits of using metformin for PCOS
Metformin may help ease several PCOS symptoms by:
- Improving insulin resistance and managing weight
- Regulating menstrual cycles and supporting ovulation, which may improve fertility
- Reducing the risk of miscarriage if you get pregnant
- Supporting heart health by reducing cholesterol
It’s often recommended if other PCOS treatments aren’t suitable and tends to cause fewer side effects than some hormone-based options.
Some people also report better energy and improved sleep, although these effects haven’t been confirmed in clinical studies.
Metformin and weight loss
PCOS affects people of all sizes, but if you’re carrying excess weight, losing just 5% of your body weight may help improve symptoms and support your health. If you’re trying to get pregnant, losing weight can increase your chances of conceiving and reduce risks for you and your baby.
While it isn’t a weight loss medication, metformin may support weight management by:
- Lowering insulin levels – which can help you lose weight and burn fat
- Reducing hunger, due to an increase in a molecule called Lac-Phe
However, GLP-1s like Wegovy are usually more effective than metformin alone for supporting weight loss in PCOS.
You may be able to take Wegovy and metformin together. And if you meet certain criteria – including a BMI over 35 with PCOS – you might qualify for NHS-funded support through a weight loss programme like Oviva’s, where you can access prescription weight loss injections like Wegovy.
Remember: taking medication isn’t a sign that you’re not doing enough. PCOS is a complex condition, and it’s common to need medical support to manage symptoms. Lifestyle changes can make a big difference – but they don’t always work on their own, and that’s not your fault.
Dosages: how much do you need to manage PCOS?
Metformin is usually taken as a tablet, and there are two types:
- Standard release: Works quickly and needs to be taken several times a day
- Slow-release: Works slowly and is usually taken once daily
You’ll start at a low dose and gradually increase it to minimise side effects. A typical dosing schedule starts at 500 mg and increases in 500 mg increments.
For standard-release tablets, your dose may increase like this:
- Start with one tablet with breakfast
- Then one with breakfast and one with your evening meal
- Eventually, you may take up to four tablets a day
Your doctor will guide you through the right dose and schedule. The maximum dose is 2,000 mg a day.
How to know metformin is helping
Metformin starts working in the body straight away – if you monitor your blood glucose levels, you might notice an improvement within 1-2 weeks. But it can take a few months to see changes in your PCOS symptoms.
Here are some signs metformin may be helping:
- Your periods return if they’ve been absent
- Your cycle becomes more regular over time
- Gradual weight loss, especially if you’re making other lifestyle changes
- Reduced unwanted hair growth, which may take a few months
What about the side effects?
Metformin is generally well tolerated – most people experience only mild side effects, if any.
The most common side effects are:
- Feeling sick (nausea)
- Diarrhoea
- Stomach ache
- Loss of appetite
Vitamin B12 deficiency is a rare side effect when taken at higher doses.
Another rare side effect is lactic acidosis, where lactic acid accumulates in the blood.
If you experience ongoing side effects, your doctor may suggest switching to slow-release metformin, which some people find easier to tolerate.
Are there any contraindications?
You shouldn’t take metformin if you have either severe liver disease or kidney failure, as this increases the risk of lactic acidosis. Before prescribing metformin, your doctor will check your kidney and liver function with a blood test.
Metformin may also not be suitable if:
- You have a severe infection
- You’re being treated for heart failure
- You’ve recently had a heart attack
- You have severe breathing or circulation issues
Your healthcare team will talk through your medical history to make sure metformin is safe and right for you.
How else can you manage your PCOS?
Medication is one way to manage PCOS, and many people benefit from it – especially when symptoms feel harder to manage on their own. Alongside medical support, small day-to-day changes can also make a real difference over time.
You might find it helpful to:
- Move regularly – a mix of cardio and resistance training can support hormone balance
- Eat balanced meals across the day to keep energy steady
- Include high-fibre, low-GI carbs – like oats, beans, wholegrains and vegetables
- Prioritise quality sleep by setting habits like no screen time an hour before bed and trying to stick to a bedtime routine
Access NHS-funded weight loss support
Losing weight can make a big difference if you have PCOS, and you don’t need to face this challenge alone. You may be eligible for NHS-funded support from Oviva.
Along the way, you can expect:
- A personalised weight loss plan and 1:1 support
- A sustainable approach to weight loss, without crash diets or counting calories
- Fully-remote support from dietitians, doctors and other experts
- A free app where you can set goals, track your progress and access learning resources
- Access to weight loss medication, when appropriate, offered via the NHS
Download your free info pack and speak to your GP about a referral.
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Weight management -
Weight management