Bananas are a beloved fruit enjoyed worldwide, not only for their sweet taste and convenience but also for their nutritional benefits. If you’re curious about the calorie content of this popular snack, you’ve come to the right place. Let’s dive into the nutritional facts of a banana, focusing on just how many calories you’ll find in this yellow fruit.
A medium-sized banana, weighing approximately 100 grams, contains around 89 calories (1). This makes it a relatively low-calorie and nutrient-dense food, perfect for a quick energy boost or a healthy addition to your meal.
Beyond just calories, bananas are packed with other essential nutrients. Here’s a detailed look at the nutrition facts for one medium-sized banana (100 grams):
- Calories: 89
- Water: 75%
- Protein: 1.1 grams
- Carbohydrates: 22.8 grams
- Sugar: 12.2 grams
- Fiber: 2.6 grams
- Fat: 0.3 grams
Carbohydrates in Bananas: From Starch to Sugar
Bananas are primarily known for being a good source of carbohydrates, which serve as the body’s main source of energy (2). What’s fascinating about bananas is how their carbohydrate composition changes as they ripen.
In unripe, green bananas, the predominant form of carbohydrate is starch. In fact, green bananas can contain up to 80% starch when measured by dry weight. This starch is what gives unripe bananas their firm texture and less sweet taste.
As bananas ripen, a natural transformation occurs. The starch is gradually converted into sugars, including sucrose, fructose, and glucose (3). By the time a banana is fully ripe and yellow, the starch content reduces dramatically, often to less than 1% of its weight. Simultaneously, the sugar content rises, making ripe bananas sweeter and softer, with total sugars potentially exceeding 16% of their fresh weight (3).
Despite their sugar content, bananas have a relatively low to medium glycemic index (GI), ranging from 42 to 58 depending on ripeness (4). The Glycemic Index measures how quickly carbohydrates in food raise your blood sugar levels. This lower GI is attributed to the presence of resistant starch and fiber in bananas, which slows down sugar absorption.
Fiber Power: Resistant Starch and Pectin
Bananas are not just about quick energy; they are also a good source of dietary fiber. Unripe bananas are particularly rich in resistant starch (5). This unique type of starch escapes digestion in the small intestine and travels to the large intestine, where it acts much like fiber.
In the large intestine, resistant starch becomes a food source for beneficial gut bacteria. These bacteria ferment the resistant starch, producing butyrate, a short-chain fatty acid (6). Butyrate is known to have positive effects on gut health and may play a role in preventing diseases like colorectal cancer (7).
Bananas also contain pectin, another type of fiber. Some of the pectin in bananas is water-soluble, and its proportion increases as bananas ripen (8). This increase in soluble pectin is a key factor in why bananas soften as they mature. Both pectin and resistant starch contribute to moderating blood sugar levels after meals, making bananas a healthier carbohydrate source.
In Conclusion
Bananas are a nutritious fruit that offers a moderate amount of calories, around 89 calories for a medium-sized banana. They are rich in carbohydrates that shift from starch to sugars as they ripen, and they provide beneficial fiber, including resistant starch and pectin. Whether you are looking for a pre-workout snack, a healthy dessert alternative, or simply a convenient and nutritious fruit to include in your diet, bananas are an excellent choice.
References
[1] United States Department of Agriculture. FoodData Central. Bananas, raw. https://fdc.nal.usda.gov/food-details/173944/nutrients
[2] Healthline. How Many Carbs Should You Eat Per Day to Lose Weight? https://www.healthline.com/nutrition/how-many-carbs-per-day-to-lose-weight
[3] Food Chemistry. Sugars and non-volatile organic acids changes during ripening and storage of banana fruit. http://www.sciencedirect.com/science/article/pii/S0144861704004023
[4] Glycemic Index. Banana. http://glycemicindex.com/
[5] Healthline. Resistant Starch 101 — Everything You Need to Know. https://www.healthline.com/nutrition/resistant-starch-101
[6] Healthline. Short-Chain Fatty Acids: Everything You Need to Know. https://www.healthline.com/nutrition/short-chain-fatty-acids-101
[7] National Center for Biotechnology Information. Butyrate and colonic health: implications for colitis and carcinogenesis. https://www.ncbi.nlm.nih.gov/pubmed/22797568
[8] Journal of Food Biochemistry. Pectic Fractions from Banana Fruit: Extraction, Fractionation, and Characterization during Ripening. http://www.sciencedirect.com/science/article/pii/S0308814608003440
