Metformin Diet: 5 Foods To Eat and 6 To Avoid

Did you know that medications can interact with the food you eat? 

Metformin is no exception. If you are taking metformin, you may want to adjust your diet accordingly.

Read on to find out why and learn which foods to include in your metformin diet and what you should avoid when taking metformin.

What is metformin?

Metformin is a drug that treats type 2 diabetes. In fact, it is one of the first choices the American Diabetes Association recommends. 

People with type 2 diabetes cannot use insulin properly. They usually have insulin resistance or decreased insulin sensitivity.

This means that they have a difficult time controlling how much sugar is in their blood.

Metformin is a diabetes drug in a class called biguanides. These are medications that prevent your liver from producing glucose.

Therefore, metformin lowers the amount of glucose your body absorbs from what you eat. It also improves your body’s response to insulin.

Metformin can be used alone. You can also combine it with insulin treatment or with an oral antidiabetic medicine called sulfonylurea. Metformin is only available with a prescription from a doctor. 

RELATED: Metformin Recall: Is Your Medication Affected?

What is metformin used for?

Metformin is a medication for type 2 diabetes. It’s also used in diabetes prevention for prediabetes.

Metformin does not help in type 1 diabetes because these people cannot produce insulin from their pancreas. Patients with type 1 diabetes usually control their blood glucose with insulin injections.

Metformin is also used in the treatment of PCOS. PCOS stands for polycystic ovary syndrome. 

This is a hormonal condition that affects ovulation and may increase androgen production. Androgens are male hormones responsible for facial hair growth and male pattern baldness.

PCOS increases the risk of developing obesity, depression, infertility, and type 2 diabetes. 

Healthcare providers sometimes use metformin in people with polycystic ovarian syndrome who are struggling with infertility. The goal is to use metformin to improve ovulation and chances of conceiving. 

In the past, metformin has also been used to help women with PCOS with bodyweight loss maintenance. This is because metformin may decrease adipose tissue mass. Metformin may also help to reduce waist circumference and help with long-term weight loss.

Metformin can also be used in the treatment of metabolic syndrome.

Foods you should avoid while taking metformin

Below are six foods you to avoid while taking metformin.

1. Fats

You should avoid foods high in trans and saturated fats when taking metformin. Healthy fats, on the other hand, are fine and you should include them as part of a healthy diet if you’re on metformin.

2. Sodium

You should avoid having too much sodium while you’re on metformin. Keep your sodium intake under 2300 milligrams per day.

3. Simple and refined carbs

Simple and refined carbs increase your blood sugar levels. Avoid simple carbs such as soda, candy, and desserts. Stay away from refined carbs such as white bread, pasta, and white rice.

4. High-fiber foods

Fiber can absorb certain drugs and lower their concentration in your bloodstream. If you eat large amounts of fiber, your metformin levels may decrease. Keep your fiber intake under 30 grams per day.

5. Alcohol

You’ll want to avoid large amounts of alcohol since it increases your risk of developing low blood sugar and lactic acidosis. Alcohol prevents the liver from storing and releasing glucose.

Since people with diabetes already struggle to manage blood sugar levels, minimizing the risk factor of alcohol consumption is worth consideration.

Drinking alcohol with an empty stomach can cause low blood sugar. This is even more true for people taking insulin or other diabetes medications that increase insulin levels.

Metformin increases the amount of lactate. Lactate is the underlying compound of lactic acid.

This isn’t of too much concern, but research shows that too much alcohol, along with a thiamine deficiency, can lead to a buildup of lactate.

Alcohol and metformin together can lead to too much lactic acid in the blood. This can lead to lactic acidosis, a serious condition.

In general, drinking in moderation is safe. Safe levels are one drink per day for women and two drinks per day for men.

Discuss this with your doctor, as it’s possible that abstaining from alcohol may be the best choice for you as an individual.

6. Grapefruit

One study looked at the effects of grapefruit on metformin in rats. Some rats were exposed to grapefruit juice and metformin, while the others were given metformin on its own. 

Researchers found that the rats that had both grapefruit juice and metformin had a higher amount of lactic acid production than the just metformin group. They may also have more weight gain.

Researchers postulated that grapefruit juice increased the accumulation of metformin in the liver. This then caused an increase in lactic acid production.

Researchers concluded that drinking grapefruit juice might lead to a higher risk of lactic acidosis in patients taking metformin.

Foods to avoid when taking metformin for PCOS

If you’re taking metformin for PCOS, you may need to adjust your diet. Below we share five foods to avoid when taking metformin for PCOS.

  • Sugary drinks: Sugary drinks like soda, sweetened teas, flavored coffee drinks, and energy drinks are very high in added sugar, which can raise your blood sugar levels quickly. Since PCOS often stems from insulin resistance, it’s best to avoid sugary drinks so metformin can more easily do its job to help improve insulin sensitivity.
  • Alcohol: Drinking alcohol can lower your blood sugar levels. If you drink a lot of alcohol while taking metformin for PCOS, you might develop even lower blood sugar levels. If you choose to drink alcohol while taking metformin for PCOS, try to limit it to no more than one drink per day.
  • Foods with added sugar: Food high in added sugar can worsen insulin resistance and PCOS symptoms. The American Heart Association recommends limiting your added sugar consumption to fewer than 25 grams per day.
  • Refined grains: Refined grains are stripped of their nutrient- and fiber-rich parts, leaving behind a lower-fiber, lower-nutrient grain. These types of grains are more likely to raise your blood sugar levels and worsen insulin resistance.
  • Fried foods: If you experience stomach side effects while taking metformin for PCOS, try cutting back on fried foods to see if that’s part of the culprit. Cutting back on fried foods might also help you lose weight, which can improve insulin sensitivity and PCOS symptoms.

how to reverse type 2 diabetes

Foods to include in your metformin diet

Below are five foods you should eat while taking metformin.

1. Complex carbohydrates

Complex carbohydrates come from vegetables, fruits, and whole grains, such as brown rice and whole-grain bread.

These carbs have more fiber, which makes them more difficult for the body to metabolize. This then slows the release of glucose into the bloodstream.

If you are consuming complex carbs, keep an eye on your overall carb intake. This is important because carbohydrates do directly affect blood sugar levels.

2. Nonstarchy vegetables

Nonstarchy vegetables can help to slow your carb metabolism. Examples of nonstarchy vegetables include broccoli and leafy greens.

3. Healthy fats

You can get healthy fats from sources such as fish, nuts, and olive oil.

4. Moderate fiber intake

Although lots of fiber is not recommended, moderate fiber intake can actually be helpful. This is because fiber can help to control blood glucose levels.

An average intake of fiber is between 25 and 30 grams per day.

5. Lean protein

Encourage the consumption of lean proteins such as turkey, fish, and tofu.

Other things to avoid while taking metformin

Fortunately, there aren’t many serious metformin drug interactions. But using some drugs while on metformin can increase the risk of lactic acidosis.

If you take any of the following medications, let your healthcare provider know:

  • Anticonvulsants, such as topiramate (Topamax) and zonisamide (Zonegran)

  • Oral contraceptives

  • Diuretics, such as acetazolamide

  • Antipsychotic drugs, such as chlorpromazine 

Get Your FREE Diabetes Diet Plan

  • 15 foods to naturally lower blood sugar levels
  • 3 day sample meal plan
  • Designed exclusively by our nutritionist

By clicking “Download Now”, I agree to Ben's Natural Health Terms and Conditions and Privacy Policy.

Should metformin be taken with food?

It is fine to take metformin on an empty stomach, but taking metformin with food is usually better tolerated and helps to reduce the stomach or bowel side effects that can occur.

Should you take metformin before or after your meals?

You might wonder whether you should take metformin before or after your meals. There are two types of metformin – regular and extended-release (XR). 

Typically, the regular tablet is taken with your meal two to three times a day. People usually take the extended-release tablet once a day with their evening meal.

As discussed above, the best way to take metformin is with your meal or just after you’ve finished eating to minimize the gastrointestinal side effects.

Talk to your healthcare provider or pharmacist for guidance on how and when you should take your metformin tablets.

Any other safety concerns?

Metformin has been associated with lactic acidosis. Although this is a rare situation, it is potentially life-threatening and therefore worth mentioning here. 

Less than ten out of every 10,000 people on metformin experience lactic acidosis. You are at higher risk if you have impaired liver or kidney function. You are also at higher risk of lactic acidosis if you have congestive heart failure.

If you have ever had an allergic reaction to a medicine, you must tell your doctor this. Any other allergies to foods, preservatives, animals, or dyes are worth mentioning as well.

In terms of metformin contraindications, this drug is contraindicated if you have diabetic ketoacidosis.

Other potential side effects of metformin include the following:

  • Nausea

  • Vomiting

  • Abdominal pain

  • Gas

How to reduce the side effects of metformin

The best way to reduce the side effects of metformin is to take it with food. The most common side effects of metformin are nausea ad diarrhea, and they happen most often if you take it on an empty stomach.

Since metformin therapy impairs your body’s ability to absorb glucose (through its effects on the gut microbiota), you may have diarrhea after eating carbs if you are on metformin.

You need to balance your dose of metformin with the foods you eat and the exercise you do. 

If you change your diet, exercise habits, or make other lifestyle interventions, you will want to test your blood sugar to ensure it doesn’t go too low. If this does happen, your healthcare provider will be able to help you out.

glyco optimizer

A word from Ben’s Natural Health

At Ben’s Natural Health, we believe that natural options are the way to go. Given the above side effects of metformin, many people prefer natural alternatives such as herbs and supplements, which can treat type 2 diabetes without side effects. 

Talk to your healthcare provider about natural diabetes treatments to see which ones may be suitable for you.


If you’re taking metformin, foods to avoid include high fiber foods, trans and saturated fats, sodium, and simple and refined carbs. Get most of your carbs from vegetables, fruits, and whole grains. 

Eat nonstarchy vegetables, healthy high fat foods, lean proteins, and a moderate amount of fiber. If you’re taking metformin, it’s worth talking with your health care provider about a metformin diet.

Explore More

natural metformin

5 Natural Alternatives to Metformin for Diabetes & Insulin Resistance.


  1. Bailey, DG; Dresser, G & Arnold, JM. (2013). Grapefruit-medication interactions: Forbidden fruit or avoidable consequences?. CMAJ. 185 (4), 309-316. 
  2. Bonnet, F & Scheen, A. (2016). Understanding and overcoming metformin gastrointestinal intolerance. Diabetes Obesity and Metabolism. 19 (4), 473-81. 
  3. Chudnovskiy, R; Thompson, A; Tharp, K; Hellerstein, M; Napoli, JL & Stahl, A. (2014). Consumption of clarified grapefruit juice ameliorates high fat diet induced insulin resistance and weight gain in mice. PLoS One. 1 (1), 1. 
  4. DeFronzo, R; Fleming, GA; Chen, K & Bicsak, TA. (2016). Metformin-associated lactic acidosis: Current perspectives on causes and risk. Metabolism. 65 (2), 20-29. 
  5. Gong, L; Goswami, S; Giacomini, KM; Altman, RB & Klein, TE. (2012). Metformin pathways: pharmacokinetics and pharmacodynamics. Pharmacogenet Genomics. 22 (11), 820-827. 
  6. Owira, PM & Ojewole, JA. (2009). Grapefruit juice improves glycemic control but exacerbates metformin-induced lactic acidosis in non-diabetic rats. Methods Find Exp Clin Pharmacol. 31 (9), 563-70. 
  7. Lashen, H. (2010). Role of metformin in the management of polycystic ovary syndrome. Ther Adv Endocrinol Metab. 1 (3), 117-128. 
  8. Owira, PM & Ojewole, JA. (2010). The grapefruit: an old wine in a new glass? Metabolic and cardiovascular perspectives. Cardiovasc J Afr. 21 (5), 280-285. 
  9. Yang, C; Chan, K; Tseng, K & Weng, S. (2016). Prognosis of alcohol-associated lactic acidosis in critically ill patients: an 8-year study. Sci Rep. 6 (1), 35368. 
  10. Siavash M, Tabbakhian M, Sabzghabaee AM, Razavi N. Severity of Gastrointestinal Side Effects of Metformin Tablet Compared to Metformin Capsule in Type 2 Diabetes Mellitus Patients. J Res Pharm Pract. 2017.

Top Products

Total Health


Glucose Control