How many calories are in a tomato?

A medium fresh tomato (around 125g) contains approximately 20-25 kcal. Per 100g, standard tomatoes provide just 17 kcal, while sweeter cherry and vine varieties reach around 26 kcal. This makes tomatoes one of the lowest-calorie whole foods you can eat — you could eat an entire kilogram and still consume fewer calories than a single chocolate biscuit.

Are canned tomatoes as healthy as fresh?

Yes, and in some ways better. Canned tomatoes are NOVA 2 — minimally processed with heat treatment. The key nutritional advantage is that cooking increases the bioavailability of lycopene, a powerful antioxidant, by up to 2-3 times compared to raw tomatoes. Just check the label: plain tinned tomatoes (like Tesco Italian Peeled Plum Tomatoes at £0.47) contain just tomatoes and tomato juice with no added sugar.

Do tomatoes spike blood sugar?

No. Tomatoes have a glycaemic index of approximately 15, which is very low. They contain only 3-4g of carbohydrates per 100g, almost all as natural sugars. The high water content (around 95%) and fibre mean they produce a negligible blood glucose response. Tomatoes are one of the safest foods for anyone managing blood sugar levels.

Glucose: Very LowNOVA 1

Nutritional Information for Tomatoes

Tomatoes are one of the lowest-calorie whole foods available, delivering just 17-26 kcal per 100g depending on variety. From a SpikeSaver perspective, they are essentially glucose-neutral with a GI of around 15 and only 3-4g of carbohydrates per 100g. Fresh tomatoes are NOVA 1, while canned or tinned varieties move to NOVA 2 due to minimal processing (heat treatment, added tomato juice). Tomatoes are also one of the richest dietary sources of lycopene, a powerful antioxidant linked to heart health and reduced inflammation.

Nutrition per 100g

Nutrient	Per 100g	Per serving
Energy	20 kcal / 84 kJ	25 kcal
Protein	0.8g	1g
Carbohydrates	3.2g	4g
of which sugars	3.2g	—
Fat	0.3g	0.4g
of which saturated	0.1g	—
Fibre	1g	—
Salt	0.01g	—

Serving size: 1 medium tomato (~125g) · Source: Tesco product page, October 2025

Glucose impact

Glycemic Index

Very Low

Glucose risk

Tomatoes contain only 3-4g of carbohydrates per 100g, virtually all as natural sugars. With a glycaemic index of approximately 15, they produce a negligible blood glucose response. You would need to eat over a kilogram of tomatoes to consume the same amount of sugar found in a single can of cola.

Processing level

NOVA 1 (unprocessed)

A fresh whole tomato is an unprocessed single-ingredient food — just tomato. No additives, no preservatives, no flavourings. Canned or tinned tomatoes (such as Tesco Italian Peeled Plum Tomatoes) move to NOVA 2 as they undergo heat treatment and may contain concentrated tomato juice, but remain minimally processed with no ultra-processed additives.

Tomatoes at Tesco

Source: Tesco product page, October 2025

Tesco Tomatoes On The Vine 500G

£1.25*NOVA 1 (unprocessed)

Tesco Beef Tomatoes Each

£0.90*NOVA 1 (unprocessed)

Tesco Organic Cherry Tomatoes On The Vine 200g

£2.00*NOVA 1 (unprocessed)

Tesco Italian Peeled Plum Tomatoes 400G

£0.47*NOVA 2 (processed culinary ingredient)

Tesco Sweet Vine Ripened Tomatoes 255G

£1.15*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 tomatoes are always NOVA 1 and glucose-safe. Canned tomatoes (NOVA 2) are still excellent — just check the label for added sugar or salt, which some brands include. Tomato-based sauces, ketchup, and pasta sauces often jump to NOVA 3-4 with added sugar, modified starch, and flavourings. Tomatoes are exceptionally rich in lycopene, and cooking actually increases lycopene bioavailability — so canned tomatoes and passata can deliver more lycopene than raw. Budget tip: Tesco Italian Peeled Plum Tomatoes at £0.47 per 400g tin is outstanding value.

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