Are Bananas Keto-Friendly? We Asked the Expert

Banana calories and carbs

Are you wondering if your beloved bananas can fit on a keto meal plan?

Known for their rich potassium content, there is no arguing that bananas are packed with nutrition, making them an ideal healthy snack for most people, especially children and athletes.

But, because over 90% of a banana’s calories come from carbs, they do not fit easily into a carbohydrate-restricted diet, especially a keto diet. 

It can be challenging to fit even one serving of fruit on a true keto diet, which restricts carbs to 5% of calories or about 20 grams per day. Just one medium banana, at about 25 grams of carbohydrates, already exceeds the 20-gram limit. This rigid carb restriction should be considered just a temporary phase of a keto diet and not a long-term sustainable way of eating. Because of possible adverse effects, the beginning phase should be overseen by a doctor or dietitian. 

The keto diet that most people follow for weight loss is known as a modified keto diet, which typically aims for less than 50 grams of net carbohydrates per day. A small banana, or 1/2 of a banana, can fit into this type of low-carb diet.



Nutrition Facts of a banana 

1 small (100 g) – 6-7 inches

  • Calories – 90
  • Total carbohydrate – 23 g
  • Fiber – 2.5 g
  • Net carbs – 20 g

1 large (136 g) – 8-9 inches

  • Calories – 121
  • Total carbohydrate – 31 g
  • Fiber – 3.5 g
  • Net carbs – ~27 g



Are Bananas a Carb?

Bananas consist primarily of carbohydrates and water. As mentioned above over 90% of the calories in a banana come from carbs, which is why they are not considered keto-friendly. The term “carbohydrate” can be misleading because not all carbs are created equal. Carbs can be complex starches or fibers, and they can be simple sugars. Your body processes these carbs differently.

About 10% of the calories from carbs in a banana come from fiber. Fiber has little to no caloric value in the body so these carbs can be subtracted from the total carbohydrates. Fiber has the added benefit of stabilizing blood sugar levels by slowing down digestion. This is why it is important to calculate net carbs on a keto diet. 

Carbs in Banana

The amount of carbs in bananas, of course, depends on the size of the banana. After accounting for the fiber, a large banana nets approximately 27 grams of carbs and one medium-sized banana nets 24 grams. A small-sized banana is about 20 grams of net carbohydrates. If you cut several bananas into 1-inch pieces and freeze them, each 1-inch piece is going to be about 3 grams of net carbs. The ripeness of a banana affects how your body processes the carbs from bananas.

A green banana is higher in a type of carb called resistant starch. Because resistant starch is digested so slowly, it doesn’t cause a spike in blood sugar the way glucose does. For this reason, green bananas have a much lower glycemic index.



Will a Banana Kick Me Out of Ketosis?

Achieving and maintaining a state of ketosis is highly individualized. This is why it is recommended that you work with a nutrition professional who can help you plan a keto diet that meets your nutritional needs, monitor, and evaluate your labs, and help you manage any side effects.

Once it is deemed safe for you to start a keto diet, a dietitian can help you figure out your goal carb intake, which takes into account your age, gender, metabolism, body composition, physical activity level, lifestyle, overall health, etc. In the initial phase of a keto diet, where the goal is to maintain a state of ketosis, high-carb fruits like bananas will not be on your meal plan.

However, this highly restrictive phase is temporary, and as more carbohydrates are added to your diet in later phases, a small banana may be included. 

On a final note, with regard to whether your body is maintaining a state of ketosis, the only way to really know is to measure ketone levels. Blood ketone levels are the most accurate measure of ketosis.



Health Benefits of Bananas

Bananas are one of the most popular fruits on earth and a favorite snack across the lifespan from infants to the elderly. They are loaded with nutrients including fiber, vitamins, minerals, and antioxidants. They are exceptionally rich in potassium, vitamin c, and vitamin B6. Bananas also contain resistant starch, which acts as a prebiotic in the body and has favorable effects on blood sugar. The greener the banana, the greater the amount of resistant starch.

How to Eat Banana on a Low-Carb Diet

The answer to this question is highly individualized. A small banana provides 20 grams of net carbs. If your goal is to eat less than 50 grams of net carbs per day, then you could fit a small banana into your meal plan, but it will fill up a good chunk of your carb allowance.

Again this is not a one size fits all diet. A highly active individual has more flexibility to include a banana on a low-carb diet. For example, a small banana with peanut butter is an excellent way to replenish and nourish the body after intense exercise. For someone who is just beginning a keto diet and in the most restrictive phase for carbs, it is best to choose only keto fruits.

A dietitian who knows your history, body composition, age, activity, and exercise levels, can help you determine if a banana is a good snack choice.

Creative Ways to Include Banana on a Low-Carb Diet

  • Cut a small banana in half, cut one half into thin slices, and top on cottage cheese. Give the other half to a family member or freeze for later. 1/2 of a small banana is 10 grams of net carbs.
  • Cut several bananas into 1-inch pieces and freeze. Throw 3 pieces into a low-carb smoothie. This will naturally sweeten the smoothie while adding important nutrients like potassium, B vitamins, and fiber. Three 1-inch pieces would provide approximately 10 grams of net carbs.

Substitutes for Bananas On Keto 

Use banana extract if you desire the flavor of banana without the added sugar. Make sure to look for products made from real bananas, not imitation or artificial flavorings. There are many ways you can use banana extract as a flavoring — in low-carb smoothies, baking, pancakes, waffles, french toast, or mix into sugar-free syrup. 

There are some lower-carb options you can use to replace bananas in a recipe, such as mashed avocado or canned pumpkin. You can also try using chia seeds. Transform chia seeds into a gel-like consistency by combining 1 tbsp. chia seeds with 3 tbsp. of water, and let soak for 5-10 minutes. Many keto-friendly recipes use this substitution to replace banana in low-carb baking. 

What Are Some Keto-Friendly Fruits?

Keto fruits lowest in net carbs per serving are açaí berries, avocados, lemons, limes, olives, coconut meat, tomatoes, star fruit, blackberries, plums, raspberries, strawberries, and watermelon.

Keep in mind that some of these fruits are only keto-friendly if you stick to the recommended portion size. 1 cup of watermelon nets 10 grams of carbs and it’s easy to quickly exceed this amount.

What Is the Lowest Carb Fruit?

After accounting for fiber, açaí berries (unsweetened) are the lowest carb fruit with 1 gram of net carbs per serving (100 grams).

Last Words

The intent of this article is not to classify bananas as bad or forbidden. Sometimes during a popular diet trend, certain foods or macronutrients become labeled as bad. For many years, high-fat foods were considered bad — like eggs, butter, coconut, and full-fat Greek yogurt. Now, most people understand that these are highly nutritious foods and that the fat content actually helps to create a sense of fullness and satisfaction. 

In a complete reversal of the “fat is bad” mentality, the keto diet has fueled the fire of the “carbs are bad” mentality. Foods that don’t fit the typical keto profile — high-fat, low-carb, and moderate in protein sometimes get tossed into the “bad” foods category. This happens to bananas because they are high in carbs. This doesn’t mean that they’re unhealthy though. It simply means that in order to stay within a certain carb budget, high-carb fruits like bananas may need to be replaced with low-carb fruits

Please note that certain groups of people are advised not to follow a ketogenic diet, including people with: type 1 diabetes, pancreatic disease, liver conditions, thyroid problems, eating disorders, gallbladder disease, pregnant or breastfeeding women, and athletes. Always check with your doctor or dietitian to first make sure it is safe for you to start a keto diet. 

References

Food Data Central. U.S. Department of Agriculture. https://fdc.nal.usda.gov/index.html

Lisa Rainer
Lisa Rainer

MS, RD - Contributor

Lisa Rainer, MS, RD is a registered dietitian nutritionist and mom of three. She earned a Master’s Degree in Nutrition from California State University, Northridge. As a graduate student, her research was published in the Journal of the American Dietetic Association. She has worked in a variety of settings as a clinical dietitian, renal dietitian, freelance writer, and in private practice. In her spare time, she loves to be out-of-doors hiking, biking, or watching her children play in their sports activities.

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