Metformin for PCOS: Best practices and foods to avoid when taking metformin for PCOS

Metformin is a medication used to treat type 2 diabetes and may also be used to manage Polycystic ovary syndrome (PCOS). However, the kind of food you consume while on this medication matters and may help you get better results. Knowing the foods to avoid while taking metformin (as you'll learn from this article) is one key way to properly manage your condition. 

Image of an overweight woman on a bed eating food, and apple drinking from a glass of juice placed on the bed

Key takeaways:

  • Metformin is a medication primarily used to treat type 2 diabetes. Although it is not officially approved for PCOS treatment, it is sometimes prescribed for this. In recent years, lifestyle changes using diet and medications like metformin have helped people with PCOS manage their symptoms and live healthier and better lives.
  • Salts, red meat, refined carbs, canned foods, and alcohol are examples of foods to avoid or limit when taking metformin for PCOS. These foods may interact negatively with metformin or reduce its efficacy, so it would be best to avoid them.
  • Metformin dosage for every individual differs depending on the number of symptoms shown and the side effects produced. Taking metformin with meals like breakfast or dinner is best for the best results.

Polycystic ovary syndrome (PCOS) is a common endocrine or hormonal condition affecting about 8 to 13% of women of childbearing age, according to the World Health Organization (WHO).  Unfortunately, 70% of those with this condition don’t know they have it.

The name "polycystic ovary syndrome" refers to the numerous small cysts that may form in the ovaries of some women with this condition. Cysts may not be present in all people with PCOS, and their presence is not what causes the syndrome most times. This condition is often characterized by hormonal imbalance, irregular menstrual cycles, and the absence of ovulation. 

Common symptoms of PCOS include: 

  • Irregular menstruation that may be long and heavy  
  • Abnormal hair growth on the face, chest, and other parts of the body
  • Oily skin and acne 
  • Obesity
  • Infertility
  • Dark, thickened skin patches around the neck, armpits, and skin folds called acanthosis nigricans  

The exact cause of PCOS is unknown, but it is thought to be related to a combination of genetic and environmental factors, so it could be termed a multifactorial condition.

Some people with PCOS are more likely to have obesity,  insulin resistance, diabetes mellitus,  systemic inflammation, or other chronic conditions that raise the risk of diabetes, cardiovascular diseases, metabolic syndrome, and endometrial cancer.

PCOS does not have a cure for now, but treatment options are available to help manage the symptoms. Therapy is designed to address each patient’s symptoms, health complications, and reproductive goals. PCOS management strategies may include:

  • Lifestyle changes such as diet, weight loss and exercise
  • Medications such as birth control pills, medications to regulate ovulation, or medications to reduce androgen levels. 
  • Laparoscopic ovarian surgery


Metformin (Glucophage) is a first-line medication for treating type 2 diabetes. It reduces the amount of glucose absorbed from the intestines, lowers the amount of glucose produced by the liver, and improves the body's response to the insulin hormone. This hormone regulates the body’s blood sugar level.

Doctors sometimes prescribe metformin for PCOS treatment, particularly for obese and diabetic people with insulin resistance or those who have not responded well to other ovulation induction medicines like clomiphene citrate. Studies have revealed that metformin can help restore ovulation, reduce weight gain, lower androgen levels, and decrease the risks of gestational diabetes and miscarriages in women.

Even while taking medications like metformin, your diet plays a significant role in the proper management of PCOS. Studies suggest that the ketogenic diet and Mediterranean diet can improve the symptoms and outcomes of PCOS.

In the following sections, we’ll discuss the best foods for people with PCOS and those they should avoid. 

7 foods people with PCOS should avoid when taking metformin and why they should avoid it

It is best to avoid or reduce the consumption of these foods while on metformin medication:

1. Sugary drinks and foods

Sugary foods and drinks can raise blood sugar levels and cause insulin resistance, inflammation, increased androgen levels, and weight gain. Since one of metformin's primary actions is to lower blood sugar, such foods can hinder the effectiveness of the treatment.

Also, glucose in the blood triggers the release of insulin, and high insulin is both a symptom of PCOS and a major driver of the condition.

Examples of sugary foods and drinks to avoid are sodas, energy drinks, juices, pastries, candy, and sugary cereals.

2. Refined carbohydrates

Refined carbohydrates like white bread, pasta, noodles, and sugary breakfast cereals (e.g., cornflakes and golden morn) can also cause blood sugar spikes. This increases the work metformin has to do to restore normal blood glucose levels. A high glucose level is also a hallmark of insulin resistance, which is associated with PCOS. 

It is best to go for whole grains and whole carbs like wheat, brown rice, potatoes, millet, and oats. These foods contain more nutrients, are more filling, and don’t spike blood glucose as fast as refined carbs. 

3. Processed foods

Processed foods include canned foods, frozen meats, hot dogs, sausages, and cookies. They may contain additives like sweeteners, preservatives, or artificial colors and are often high in saturated fats, sodium, and sugar. Heavily processed foods can trigger inflammation, which can induce or worsen PCOS symptoms and interfere with metformin's effectiveness. 

4. Fried foods

Fried foods are high in calories and saturated fats, which are unhealthy and can contribute to weight gain and chronic inflammation. Therefore, if you consume fried foods excessively, it might be harder for metformin to help with weight management (which is crucial for PCOS management).

5. Red meat

Red meat contains high amounts of saturated fats, which can contribute to insulin resistance, inflammation, and low progesterone levels when consumed in high amounts. Reducing or avoiding red meat intake may be beneficial for those on metformin.  A better option is to eat lean protein like fish and poultry. 

6. High-sodium foods

High sodium intake can worsen insulin resistance, high blood pressure, and inflammation. While on metformin medication for PCOS, cooking with less salt and natural spices is advisable.

7. Alcohol

Excessive alcohol intake while on metformin may increase the risk of lactic acidosis two times higher. This can cause weakness, fatigue, nausea, difficulty breathing, or a medical emergency. 

Additionally, alcohol consumption may lead to unpredictable blood sugar fluctuations by increasing or reducing it at will. This would disrupt the work done by metformin in trying to regulate the blood sugar level. Therefore, it is best to avoid alcohol consumption while on metformin.

Foods to consume when taking metformin for PCOS

Remember that moderation is the key to achieving any goal with diet plans. Here is the list of foods to consume when taking metformin for PCOS:

High-fiber foods

Fiber helps regulate blood sugar levels and reduce weight gain and cholesterol levels. These are beneficial for treating PCOS.

You can get fiber from: 

  • Whole grains like brown rice, barley, quinoa, oats, wheat, and millet
  • Fruits 
  • Leafy greens like broccoli, spinach, lettuce, pumpkin leaves, water leaves, and kale 
  • Carrots
  • Tomatoes
  • Cabbage 
  • Cauliflower 
  • Peas 
  • Mushrooms 
  • Celery 
  • Fennel

Vegetables are also a great source of vitamins and phytonutrients that help reduce inflammation in PCOS.


Legumes are a good source of plant-based proteins. They have a low glycemic index, meaning they’re less likely to cause sharp fluctuations in blood sugar. 

Low-glycemic index foods are better food options than high-glycemic foods because they contain little sugar, may help prevent coronary heart disease in diabetic people, and may help obese or overweight people feel full and have portion control. Examples of legumes to add to your diet are black beans, soy beans, lentils, and chickpeas.

Lean protein

Lean protein foods are protein sources with lower fat content that help with satiety and weight management. They also help to reduce inflammation and improve insulin sensitivity. Examples of lean protein foods are fish (salmon, sardines, mackerel, and herring), skinless chicken or turkey breast, and eggs. 

Seeds and nuts

Most plant seeds are packed with fiber, omega-3 fatty acids, and zinc, which studies have shown to support regular ovulation in PCOS by regulating hormonal imbalance

Seeds also help with weight loss, blood sugar control, and insulin resistance. Chia, flax, pumpkin, sesame, and sunflower seeds are examples of healthy seeds to include in your diet.

Healthy fats

Unsaturated fats are considered healthy because they help reduce blood sugar levels, improve insulin levels, and reduce insulin resistance. Excellent sources of healthy fats are avocados, nuts, and seeds (almonds, walnuts, flaxseeds, and olive oil), and omega-3-rich fish ( salmon, herring, sardines, and mackerel).

Low glycemic index fruits

Just because you’re trying to cut down on your sugar intake doesn’t mean you can’t enjoy fruits. Fruits with a low glycemic index contain lower amounts of sugar and high fiber, which helps reduce blood glucose, boost insulin, and lower androgen levels in people with PCOS. 

Examples of fruits you can enjoy are cucumber,  apples, grapes, oranges, plums, kiwis, peaches, pears, and berries such as blueberries, raspberries, and strawberries.

Probiotic foods

Probiotics contain live microorganisms like yeast or bacteria that help boost the healthy bacteria in the gut. Consuming probiotic foods can aid in the correction of hormonal imbalance and reduce androgen levels and inflammation in people with PCOS.  You can find probiotics in yogurt, kefir, kimchi, natto cottage cheese, buttermilk, tempeh, sauerkraut, kombucha, miso soup, and pickles.

Metformin may not start working immediately after you take it. And for people with PCOS, it may work faster when combined with other medications like clomiphene citrate.

When should you take metformin?

Metformin is available as tablets, liquid formulations, and sachets in 500mg, 850mg, and 1000mg doses. Your health provider will prescribe how much of this drug you should take daily, typically starting with a lower dose. 

The dosage of metformin you’re given is gradually increased every week depending on the body’s response. It may also follow an evening-morning-evening pattern. All these will enable the gynecologist or endocrinologist to monitor and track the duration of treatment.

Some people may experience adverse effects like diarrhea, nausea, vomiting, headaches, flatulence, and abdominal pain from taking metformin. Report to your doctor if you have severe side effects from taking this medication, and they may put you on slow-releasing metformin tablets or change your treatment entirely.

Metformin and potential drug interactions

Metformin can interact with certain drugs and cause adverse effects when combined. Make sure your doctor is aware you are on other medications to avoid any potential drug interactions. Some of the drugs that can interact with metformin are listed below.

  • Metformin can increase the risk of hypoglycemia when combined with these medications that decrease blood sugar levels in diabetic patients. Some of these drugs are Insulin, Glipizide (Glucotrol XL) and Repaglinide. This interaction may cause symptoms like increased heartbeat, anxiety, dizziness, confusion, and seizures in people with PCOS.
  • Metformin can interact with medications that cause hyperglycemia (high blood sugar) when combined. They include Prednisone, Hydrochlorothiazide (Microzide), Olanzapine (Zyprexa), Metoprolol (Lopressor), Simvastatin (Zocor) and Phenytoin (Dilantin, Phenytek). If metformin is overpowered in this interaction, there is increased hyperglycemia, which can result in complications like diabetic ketoacidosis, stroke, and kidney failure.
  • Metformin can cause lactic acidosis when combined with medications like topiramate (Topamax)  and cimetidine ( Tagamet HB). It can also induce lactic acidosis when combined with alcohol.
  • Metformin can interfere with vitamin B12 absorption, leading to vitamin B12 deficiency. 

Wrap Up

PCOS is the most common hormonal disorder affecting women in their reproductive age. This condition interferes with a woman’s menstrual cycle, making conception difficult in most cases. The cause of PCOS is unclear, and symptoms include obesity, anovulation, irregular menstruation, acne, and abnormal hair growth.

All these make it difficult to manage with a particular drug, hence the reason it has no cure yet. Nevertheless, with some medications like metformin, dietary changes, weight loss, and exercise, people with PCOS have been able to live their lives to the fullest and bear children too.

Sugary foods, drinks, alcohol, fries, and processed foods can interfere with metformin's effectiveness in the body and should be avoided. High-fiber foods, probiotics, lean protein, healthy fats, and low-glycemic fruits are very beneficial to PCOS treatment. They help with better blood sugar control, insulin resistance, weight management, and regular menstrual cycle.

To achieve the best results, people with PCOS should consider working with a registered dietician to help draw up an appropriate meal plan.

Frequently Asked Questions (FAQs)

Should PCOS patients always take metformin with food?

Taking metformin with food is generally recommended to minimize side effects such as nausea, diarrhea, bloating, and abdominal pain. 

Starting with a low dose of 500mg daily with an evening meal for 1-2 weeks may help reduce the side effects and improve tolerance. It is very important to discuss this with your doctor to determine the best approach for you.

How long does it take metformin to work for PCOS?

How long it takes for metformin to work for PCOS depends on several factors, such as the individual involved, the number of symptoms presented, side effect tolerance, and other related health conditions. For some people, it takes a few weeks; for others, it takes months or years. 

For most people, especially those who are obese, it takes at least six months, when combined with clomiphene citrate and lifestyle changes, to notice the effect of metformin on PCOS.  During this period, metformin may help correct the menstrual cycle and reduce insulin resistance and the body mass index of obese people.


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