How many calories are in a banana?

A medium banana (about 150g edible portion after peeling) contains approximately 135 kcal. A small banana (~100g) has around 90 kcal. Per 100g of edible flesh, all bananas at Tesco provide 90 kcal regardless of whether they are loose, organic, or in packs — the nutritional content is identical.

Are bananas high in sugar?

Compared to other fruits, yes. Bananas contain 18.1g of sugar per 100g, which is higher than apples (11.6g), pears (10.9g), and strawberries (~4.9g). A single medium banana delivers around 27g of sugar — about the same as a small chocolate bar. However, this is naturally occurring sugar within a whole-food matrix that includes fibre, potassium, and vitamin B6. The glucose response is moderate (GI ~51), not sharp.

Does a green banana have a lower GI than a ripe one?

Yes, significantly. A green or just-turning banana contains more resistant starch, which your body digests slowly — giving it a GI as low as 30. As the banana ripens, that resistant starch converts to simple sugars (fructose, glucose, sucrose), raising the GI to 51 for a standard yellow banana and potentially 60+ for a very ripe banana with brown spots. If you are managing blood sugar, choosing slightly green bananas — or Tesco Ripen At Home Bananas before they fully ripen — is a practical way to reduce glucose impact.

Glucose: MediumNOVA 1

Nutritional Information for Banana

Bananas provide 90 kcal per 100g with 20.3g of carbohydrates, of which 18.1g are sugars — making them one of the higher-sugar fruits. From a SpikeSaver perspective, bananas have a medium GI of around 51, meaning they produce a moderate glucose response. Ripeness matters: a green banana has more resistant starch and a lower GI, while a very ripe banana converts that starch to sugar, raising GI significantly.

Nutrition per 100g

Nutrient	Per 100g	Per serving
Energy	90 kcal / 380 kJ	135 kcal
Protein	1.2g	1.8g
Carbohydrates	20.3g	30.5g
of which sugars	18.1g	—
Fat	0.1g	0.2g
of which saturated	0.1g	—
Fibre	1.4g	—
Salt	0.01g	—

Serving size: 1 medium banana (~150g edible portion) · Source: Tesco product page, October 2025

Glucose impact

Glycemic Index

Medium

Glucose risk

Bananas have a medium glycaemic index of approximately 51, with a glycaemic load of around 13 per medium banana. The 18.1g of sugar per 100g is entirely natural fructose, glucose, and sucrose. While this is higher than most fruits, the fibre content (1.4g/100g) and the physical structure of the fruit slow digestion somewhat. Ripeness is the key variable — a green banana can have a GI as low as 30 due to resistant starch, while a very ripe banana with brown spots can reach GI 60+.

Processing level

NOVA 1 (unprocessed)

A fresh banana is a single-ingredient whole fruit — completely unprocessed. Every fresh banana product at Tesco, whether loose, in packs, organic, or ripen-at-home, is NOVA 1. Banana-derived products like banana milk or banana-flavoured bars are entirely different products and score NOVA 3-4.

Banana at Tesco

Source: Tesco product page, October 2025

Tesco Bananas Loose

£0.16*NOVA 1 (unprocessed)

Tesco Ripe Bananas 5 Pack

£0.78*NOVA 1 (unprocessed)

Tesco Ripen At Home Bananas 5 Pack

£0.78*NOVA 1 (unprocessed)

Tesco Fairtrade Organic Bananas 5 Pack

£1.50*NOVA 1 (unprocessed)

Tesco Small Bananas 6 Pack

£0.75*NOVA 1 (unprocessed)

*Prices were correct at the time of collection and may have since changed. Check Tesco.com for current pricing.

What to watch for when shopping

Fresh bananas are always NOVA 1. The processed banana products to be cautious about are banana chips (often fried in palm oil with added sugar), banana-flavoured milk (contains sugar, flavourings, stabilisers), and dried banana bars. If you are watching blood sugar, choose slightly green bananas over very ripe ones — the resistant starch in greener bananas produces a significantly lower glucose response. Budget tip: Tesco Bananas Loose at 16p each is the cheapest option and nutritionally identical to every other fresh banana.

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