Bananas are widely consumed fruits, celebrated for their convenience, potassium content, and natural energy boost. Because they have a reputation for being a high-carbohydrate food, many people managing their carb intake question their place in their diet. Understanding the precise carbohydrate content requires focusing on the specific nutritional data tied to serving size. This analysis provides the carbohydrate and calorie information for a small banana and explores how the fruit’s composition changes over time.
The Core Answer: Carb Content by Size
A small banana, defined by the USDA as measuring approximately 6 to 7 inches in length and weighing around 101 grams, contains a specific amount of total carbohydrates. This size typically provides about 23 grams of total carbohydrates. The associated calorie count is approximately 90 calories, with over 90% of those calories coming directly from the carbohydrates.
Variation in size significantly impacts these numbers, which is important for accurate dietary tracking. A medium banana (7 to 8 inches) contains roughly 27 grams of carbohydrates and 105 calories. A large banana (8 to 9 inches long) increases the total carbohydrate content to about 31 grams, supplying around 121 calories. A small banana therefore offers a measurably lower carbohydrate option compared to its larger counterparts.
The Carbohydrate Breakdown
The total carbohydrate count in a moderately ripe small banana is a combination of three components: sugars, dietary fiber, and starch. The majority of carbohydrates are natural sugars, primarily fructose, glucose, and sucrose, which the body quickly processes for energy. A small banana typically contains about 12 grams of these simple sugars.
This fruit also contributes a beneficial amount of dietary fiber, with a small banana providing roughly 2.6 grams. Fiber is a carbohydrate the body cannot digest; it passes through the digestive tract largely intact, promoting satiety and regularity. The remainder of the carbohydrate content is composed of starch, a complex carbohydrate slower to break down than simple sugars.
Ripeness and Carb Composition
The nutritional profile of a banana is not static; it undergoes a transformation as the fruit ripens. This change is driven by natural enzymes that convert complex carbohydrates into simpler forms. In a green, unripe banana, the carbohydrate content consists mainly of resistant starch, which can account for up to 70% of the dry weight.
Resistant starch functions similarly to soluble fiber, bypassing digestion in the small intestine and having a minimal impact on blood sugar levels. As the banana matures and turns yellow, enzymes break down this resistant starch into digestible sugars: glucose, fructose, and sucrose. This conversion explains why a ripe banana tastes sweeter than a green one.
This process also affects the fruit’s glycemic index (GI), which measures how quickly a food raises blood glucose. The GI is lower for green bananas due to the high resistant starch content, making them a slower-releasing energy source. As the banana ripens and the sugar content increases, its GI rises, which is a consideration for those monitoring blood sugar. The soft texture of a fully ripe banana is another result of this carbohydrate breakdown, as starches and pectin compounds change form.
Fitting Bananas into Low-Carb Diets
Integrating a small banana into a structured diet plan requires a strategic approach, particularly for those following low-carb or ketogenic protocols. Since a small banana contains 23 grams of carbohydrates, it typically exceeds the strict daily limit of 20 to 50 grams for a ketogenic diet. For those following a less restrictive low-carb plan, this size can occasionally be accommodated, but careful portion control is necessary.
A practical strategy is to consume the banana with a source of protein and healthy fat, such as nut butter or Greek yogurt. This pairing helps slow down the digestion and absorption of the fruit’s natural sugars, moderating the subsequent rise in blood sugar. Choosing a slightly under-ripe banana, which retains more resistant starch, is also a beneficial tactic for minimizing the glycemic impact. For individuals managing blood sugar, such as those with diabetes, a small banana is a significant carbohydrate serving. It may be best consumed post-exercise when muscle cells are more receptive to glucose uptake.