Calories in a Banana: Nutrition Facts and Health Insights

You’ve probably grabbed a banana as a quick snack without giving its calorie count much thought. A medium banana delivers around 105 calories along with 15 grams of natural sugar — numbers that often raise questions about weight loss and blood sugar, so here’s a closer look at the evidence to help you decide where this convenient fruit fits in your diet.

Average calories (medium banana): 105 kcal ·
Carbohydrates: 28 g ·
Natural sugar: 15 g ·
Fiber: 3 g ·
Protein: 1 g ·
Potassium: 422 mg

The six key figures below show the macronutrient split that drives banana’s reputation as a nutrient-dense snack. Notice that fiber accounts for about 11% of total carbs — a ratio that helps blunt blood sugar spikes.

How many calories are in 1 average banana?

Banana calories depend heavily on size. According to the USDA SNAP-Ed, a medium banana (118 grams) contains 105 calories, 27 grams of carbohydrates, 3 grams of fiber, and 14 grams of sugar. That aligns with data from the Harvard T.H. Chan Nutrition Source (university nutrition research center), which reports 110 calories for a slightly riper fruit.

Calories by banana size

• Extra-small (81g): ~72 calories — Noom Blog (behavioral weight-loss platform)
• Small (101g): ~90 calories — Noom Blog
• Medium (118g): ~105 calories — Harvard T.H. Chan Nutrition Source
• Large (136g): ~121 calories — Noom Blog

The implication: a single banana accounts for only 5–6% of a 2000-calorie diet, making it a relatively low-energy food regardless of size.

Calories in a banana with peanut butter

Pairing banana with peanut butter is a classic snack, but it roughly doubles the calorie count. One medium banana (105 cal) plus 2 tablespoons of peanut butter (≈190 cal) comes to about 295 calories. Healthline (medically reviewed nutrition site) notes this combo can be a balanced mini-meal with protein and healthy fats, though portion control matters if you’re watching total intake.

Calories in a banana slice

A typical slice from a medium banana weighs about 15 grams and contains roughly 13 calories, per Eat This Much (calorie database). That makes banana a reasonable topping for cereal or oatmeal without blowing your daily budget.

Protein and carbs in a banana

One medium banana provides about 1 gram of protein (NutriScan App) and 27–28 grams of carbohydrates (Harvard T.H. Chan Nutrition Source). The carb load makes it a popular pre-workout fuel: the 27g of carbs replenish glycogen, and 422mg of potassium help prevent muscle cramps.

Is 1 banana a day too much sugar?

A medium banana contains about 15 grams of natural sugar (Harvard T.H. Chan Nutrition Source). That’s roughly the same amount as a small apple, and far less than a 12-ounce soda (∼40g added sugar). Healthline points out that the fiber in bananas slows digestion and blunts blood sugar spikes, making them a better choice than high-sugar processed foods.

Natural sugar versus added sugar

Bananas contain only naturally occurring sugars — fructose, glucose, and sucrose — packaged with fiber and micronutrients. The USDA’s SNAP-Ed program (government nutrition education) lists bananas as a whole fruit that contributes to recommended fruit intake without added sugars.

Daily sugar recommendations

The American Heart Association recommends no more than 25–36 grams of added sugar per day for most adults. Since banana sugar is naturally occurring, it doesn’t count toward that limit — but total carbohydrate intake matters for people with diabetes. The Harvard T.H. Chan Nutrition Source notes that one banana provides about 10% of the daily carbohydrate needs for a 2000-calorie diet.

Bananas in a balanced diet

For most people, one banana per day is well within healthy limits. The fiber (3g per medium banana) increases fullness and helps regulate blood sugar, as reported by Noom Blog (behavioral weight-loss platform). Green bananas offer even more resistant starch, which further stabilizes glucose response. The pattern: one banana a day fits easily into a balanced diet — the risk isn’t the fruit itself but displacing other vegetables and proteins.

Are bananas good for dieting?

With 105 calories and 3g of fiber per medium fruit, bananas are a low-energy-density food that can support weight loss when eaten in moderation. Noom Blog highlights that the fiber promotes satiety, helping you feel full with fewer total calories.

• Low calorie density: 0.89 kcal/g
• 3g fiber per medium banana improves satiety (Harvard T.H. Chan Nutrition Source)
• Portable and naturally packaged — reduces temptation for ultra-processed snacks

An apple provides about 95 calories with 4g fiber, and a cup of strawberries has 55 calories with 3g fiber. Bananas sit in the middle — higher in calories than berries but richer in potassium and vitamin B6. The catch: bananas are more calorie-dense than most berries, so volume control matters more.

Why do some doctors say not to eat bananas?

Some health professionals advise caution with bananas for specific medical conditions — not because they’re unhealthy, but because their nutrient profile can be problematic for certain populations.

Potassium and kidney concerns

One medium banana provides 422mg of potassium. For people with chronic kidney disease, excess potassium can be dangerous. The Harvard T.H. Chan Nutrition Source notes that individuals on dialysis or with impaired kidney function should consult their doctor about banana intake.

Sugar and diabetes management

Bananas have a glycemic index (GI) that ranges from 42 to 62 depending on ripeness, placing them in the low-to-medium category. For diabetics, portion size and ripeness matter more than total avoidance. Healthline recommends choosing less-ripe bananas because they have more resistant starch and a lower GI.

Ripeness and blood sugar impact

As bananas ripen, starches convert to sugars. A green banana has a GI of about 30–42, while a fully ripe banana can reach 51–62. The fiber content remains stable, but the sugar load increases, which can affect post-meal glucose levels.

Allergies and sensitivities

Banana allergies are rare but exist, often linked to latex-fruit syndrome. People with known allergies should avoid bananas entirely. Additionally, those on low-carb or ketogenic diets often limit bananas because of the 28g carb count per medium fruit.

Which fruit can burn belly fat?

No fruit specifically targets belly fat. Spot reduction is a myth: fat loss occurs from the whole body when you maintain a calorie deficit, as emphasized by Healthline. However, some fruits support overall fat loss better than others.

Spot reduction myth

Ab exercises and “belly-burning foods” don’t selectively remove abdominal fat. Noom Blog explains that a calorie deficit combined with whole foods, including bananas, can reduce overall body fat over time.

Fruits that support overall fat loss

• Berries (low calorie, high fiber)
• Apples (~95 cal, 4g fiber)
• Grapefruit (some studies suggest modest appetite suppression)
• Bananas (provide energy for exercise, which supports calorie burn)

Healthline notes that bananas can be part of a fat-loss diet but are not a magic bullet. The key is overall diet quality and adherence to a calorie deficit.

Role of bananas in a calorie deficit

Bananas offer a convenient, portable snack that can replace higher-calorie options. A medium banana at 105 calories is a smart swap for a 200-calorie granola bar. Pair it with protein (like Greek yogurt or peanut butter) for better satiety. Noom Blog suggests using bananas as a pre-workout fuel to maintain intensity during exercise, which can increase total daily energy expenditure.

Frequently asked questions