Foods to avoid while taking metformin: A complete guide to nutrition with PCOS

In a nutshell

Metformin is one of the most often prescribed medicines for treating PCOS symptoms. Reducing blood sugar and insulin levels in your body, this medicine is traditionally used in type 2 diabetes patients and hence, requires sticking to a proper diet while taking it. The primary foods to avoid when taking metformin for PCOS include:

• High-sugar foods
• Foods containing bitter melon
• High-fat products
• Refined carbohydrates
• Alcohol

Although PCOS can affect your physical and emotional health, as well as your sexual life and relationships, living with it can be comfortable thanks to optimal treatment. Yet, it’s crucial to know about the foods to avoid when taking metformin for PCOS to make your treatment effective.

PCOS: Definition, symptoms, and diagnosis

Polycystic ovary syndrome or PCOS is a hormonal condition affecting the female menstrual cycle and reproductive health. Often causing hormonal imbalances, PCOS can greatly affect your emotional wellness, everyday comfort, sexual desire, relationships, and overall health. The common symptoms of this syndrome include:

• Abnormal menstruation (e.g. missing or rare periods, prolonged menstruation, etc.)
• Acne on the face, chest, and back
• Excess hair growth (hirsutism)
• Cysts
• Weight gain and obesity
• Fertility issues

Whether you do or don’t have the aforementioned symptoms, a healthcare provider might diagnose PCOS based on the results of your physical exam, pelvic exam, or pelvic ultrasound.

How is PCOS treated?

This condition, albeit can’t be cured completely yet, is manageable with the help of different treatment methods. A healthcare provider can assess your condition and suggest suitable treatment methods to ease your PCOS symptoms.

Available treatment options include:

• Hormonal birth control
• Medications to block androgens
• Insulin-sensitizing medicine

Metformin for PCOS

Among all treatment options, metformin has shown to be one of the most effective and thus, popular methods. It’s one of the longest-established oral insulin-sensitizing agents that has been used to manage type 2 diabetes for many decades. It helps your body sense and process insulin to keep its levels under control.

In the past two decades, as the properties of insulin-sensitizing agents have been found to help manage PCOS, these medicines were integrated into the treatment of this syndrome. Metformin has become one of the most effective treatment options for anovulatory infertility among women with PCOS.

The effects of metformin on your body

Metformin helps manage PCOS symptoms by lowering blood sugar and insulin levels in your body. Once these are under control, it can improve your ovary’s function, restoring regular periods.

Common side effects of taking metformin include:

• Nausea
• Vomiting
• Diarrhea
• Loss of appetite
• Stomach ache
• Vitamin B12 deficiency

5 foods to avoid when taking metformin for PCOS

Since metformin, in essence, is a medicine meant for treating type 2 diabetes, it requires you to adhere to a specific diet while taking it. Why? - Certain foods can interfere with metformin’s ability to manage insulin and blood sugar levels in your body, respectively, hindering the effectiveness of your treatment. Additionally, some foods and drinks can enhance the likelihood of side effects, including gastrointestinal discomfort.

So what foods should you avoid while taking metformin? Let’s look at the top five types of products to steer clear of:

1. High-sugar foods

Sugary foods, such as sweet snacks, desserts, cakes, juices, fizzy beverages, and others instantly spike your blood sugar levels and significantly worsen insulin resistance. Respectively, they might be counteracting the effects of metformin.

What happens if you eat a lot of sugar while taking metformin? First and foremost, such foods can drastically lower the effectiveness of your treatment. Besides, spiking blood sugar levels while taking metformin can worsen side effects and make you experience nausea, upset stomach, or diarrhea. To avoid this, it’s recommended to steer clear of sugary foods during your treatment.

Pro tip: To ensure you’re on the safe side, always read the nutrition labels on foods and drinks you’re consuming. Sometimes, there might be hidden sugars in pretty large amounts even in products in which you don’t expect them to be, such as sauces, low-fat yogurts, ready meals, etc.

2. Bitter-melon-containing foods

Bitter melon (or karela) is a tropical vine originating from India and other Asian countries. Sometimes, it’s added to flavor different foods, for example, bitter gourd masala or to add a bitter taste to some beverages including teas and juices.

The reason you want to avoid foods containing bitter melon is because this vine is proven to have a mild hypoglycemic effect, similar to metformin. Simply put, it can also lower your blood sugar levels. An uncontrolled or significant drop in blood sugar can potentially lead to hypoglycemia.

3. High-fat foods

Processed foods that are high in fats and calories should also be avoided while taking metformin. Studies show that diets containing a large amount of high-fat foods lower the extent and rate of metformin absorption. Consuming such foods daily can lead to the necessity for increased metformin doses. Otherwise, it can hinder the effectiveness and time of treatment.

On top of that, high-fat foods are known to slow our digestion. Thus, when combined with metformin, such foods can lead to gastrointestinal discomfort, such as bloating, nausea, and other metabolic complications.

4. Refined carbohydrates

White bread, pastries, juices, breakfast cereal, white rice, and potato chips - these all are examples of refined carbohydrates. Such foods spike glucose levels in your blood. They can lead to increased weight gain and reduce the effectiveness of metformin. Due to this reason, these foods are recommended to be excluded from your diet during metformin intake.

5. Alcohol

Although the general recommendations imply that you can drink alcohol while taking metformin (no more than 2 units per day), it’s important to be incredibly careful when it comes to mixing metformin and alcohol.

Alcohol affects your body in a number of ways. It can increase your blood sugar (when consumed in moderate amounts) or make it drop significantly (when you consume alcohol excessively). Also, when having to remove alcohol-related poisons from your body, your liver undergoes significant stress, gets tired, and releases less glucose. Over time, alcohol use can make your cells absorb less glucose from the blood, hindering your insulin sensitivity. 

All in all, the effects of alcohol on your body can interfere with the work of metformin and lead to more adverse gastrointestinal side effects, including nausea, vomiting, diarrhea, abdominal discomfort, and increased risk of lactic acidosis.

What fruits to avoid when taking metformin?

Since we’re talking about blood sugar levels, one of the most common concerns facing women taking metformin for PCOS is whether they need to eliminate certain fruits from their diets.

As you may know, many fruits contain natural sugars. On the one hand, natural sugar can also affect your blood sugar levels. However, it doesn’t work exactly the same as added sugars. So all in all, it’s okay to eat fruits (and vegetables) with natural sugars even when you’re taking metformin.

On the other hand, it’s worth noting that some fruits are known to have a higher sugar content. These include:

• Mangoes
• Grapes
• Cherries
• Pears
• Watermelon
• Figs
• Bananas

While you can still enjoy these fruits during your PCOS treatment, it’s advised to eat them in moderation to avoid consuming too much sugar.

What to eat while on metformin?

As you now know, there are some foods to avoid while taking metformin. On the good side, there are also foods that can help balance out your diet and support metformin’s effect, while helping you feel healthy and active. These foods include:

1. Low GI foods

Foods with a low glycemic index (GI) are known to help you lose weight, maintain a healthy body mass index, reduce insulin resistance, and control blood sugar levels. Respectively, these foods are good to add to your diet while on metformin.

Feel free to diversify your daily meal plan with legumes, nuts, berries, and leafy greens.

2. Healthy fats

A sufficient supply of healthy fats to your organism is pivotal for managing PCOS. Healthy fats, such as Omega 3, help support the right balance of female hormones. Additionally, healthy fats promote heart health and improve insulin resistance.

Some healthy fatty products to include in your diet include nuts, seeds, olive oil, and avocado.

3. Lean proteins

Lean proteins break down into glucose slower compared to carbohydrates and sugars, hence, their effect on blood sugar is never as drastic and quick. Thanks to this, lean proteins tend to help stabilize blood sugar, manage weight, and maintain lean muscle mass.

To get these benefits, add products like chicken, fish, turkey, and tofu to your diet.

Final verdict

Although PCOS can have a significant effect on your life, managing its symptoms is possible with proper treatment. Metformin is being more and more often prescribed to females with PCOS to help them manage blood sugar, improve ovary function, and restore regular periods.

While metformin has shown its efficacy in women with PCOS, it requires adhering to a specific diet like any other diabetes medicine. After reading this article, you should have a complete understanding of which foods to avoid when taking metformin for PCOS and which foods to include in your daily diet. Use this knowledge as a guide to your proper nutrition during PCOS treatment and ensure its efficiency.

List of references:

1. “Polycystic Ovary Syndrome (PCOS).” Cleveland Clinic, 15, Feb. 2023. https://my.clevelandclinic.org/health/diseases/8316-polycystic-ovary-syndrome-pcos 
2. “Hirsutism.” Cleveland Clinic, 8, Jul. 2022. https://my.clevelandclinic.org/health/diseases/14523-hirsutism 
3. Neil P. Johnson. “Metformin use in women with polycystic ovary syndrome.” Annals of Translational Medicine, 27, Jun. 2014. https://atm.amegroups.org/article/view/3899/html#B10 
4. “Side effects of metformin.” The National Health Service (NHS), 24, Mar. 2022. https://www.nhs.uk/medicines/metformin/side-effects-of-metformin/ 
5. Fuangchan A, Sonthisombat P, Seubnukarn T, Chanouan R, Chotchaisuwat P, Sirigulsatien V, Ingkaninan K, Plianbangchang P, Haines ST. “Hypoglycemic effect of bitter melon compared with metformin in newly diagnosed type 2 diabetes patients.” J Ethnopharmacol, 24, Mar. 2011. https://pubmed.ncbi.nlm.nih.gov/21211558/ 
6. “Hypoglycemia (Low Blood Sugar).” Cleveland Clinic, 31, Jan. 2023. https://my.clevelandclinic.org/health/diseases/11647-hypoglycemia-low-blood-sugar 
7. Sun ML, Liu F, Yan P, Chen W, Wang XH. “Effects of food on pharmacokinetics and safety of metformin hydrochloride tablets: A meta-analysis of pharmacokinetic, bioavailability, or bioequivalence studies.” Heliyon, 1, Jul. 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10344758/ 
8. “Common questions about metformin.” The National Health Service (NHS), 24, Mar. 2022. https://www.nhs.uk/medicines/metformin/common-questions-about-metformin/ 
9. Michael Dansinger. “Diabetes and Alcohol.” WebMD, 21, May, 2023. https://www.webmd.com/diabetes/drinking-alcohol 
10. Berkshire Healthcare Foundation Trust Dietitians. “Polycystic Ovary Syndrome (PCOS) dietary advice.” Berkshire Healthcare Foundation Trust, Nov. 2022. https://www.royalberkshire.nhs.uk/media/afta2biw/pcos-dietary-advice_nov22.pdf