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Watermelon nutrition: glycemic index, calories, net carbs, diets

Watermelon, raw
*all the values are displayed for the amount of 100 grams
Article author photo Victoria Mazmanyan by Victoria Mazmanyan | Last updated on October 12, 2023
Medically reviewed by Ani Harutyunyan Article author photo Ani Harutyunyan


Watermelon has become a symbol of summer in numerous cultures. It is refreshing and bright and consists of more than ninety percent water, hence the name.

We will talk about the part of the watermelon that isn’t water, how it affects our health, and how it fits into different diets. In other words, we are here to tell you everything you want to know about watermelon. 

Classification and Varieties

In its botanical classification, watermelon is called a pepo: a modified berry with a thick and hard outer rind. It is loosely considered a melon; however, it is not in the Cucumis genus of melons. Instead, it is in the same Cucurbitaceae family as melons, cucumbers, and pumpkins.

The stripes of a watermelon indicate its variety. There are over 1200 watermelon varieties; however, the most popular ones are the seeded, seedless, mini, or yellow and orange watermelons.


The origin of watermelon is disputable. Scientists agree that watermelon’s progenitor was cultivated in the continent of Africa. The debate starts with the question of where exactly.

5000-year-old remnants of watermelon seeds were found in Libya. In Egyptian tombs, there were not only 4,000-year-old seeds but also paintings of watermelons. Centuries later, it spread and found popularity in Mediterranean countries (1).


Every part of the watermelon is technically edible; thus, it is considered a zero-waste food. Watermelon seeds and the rind naturally have different nutrition values than red flesh. The seeds are often roasted, and the rind can be used as a vegetable, stewed, fried, or pickled.

Some recommend incorporating watermelon seeds in traditional recipes, especially in areas where chronic hunger is an issue, as it is usually locally available and thrown away, to improve the intake of protein, fat, calcium, carbohydrates, and phosphorus (2).

Macronutrients and Calories

Around 92% of a watermelon’s weight is water; only 8% consists of nutrients.

One average serving size of watermelon per person is one slice or 280g.

A 100g of watermelon contains only 30 calories, while one average serving contains 84.

Macronutrients chart

8% 89%
Daily Value: 1%
0.61 g of 50 g
Daily Value: 0%
0.15 g of 65 g
Daily Value: 3%
7.55 g of 300 g
Daily Value: 5%
91.45 g of 2,000 g
0.24 g


The predominant macronutrients in watermelon are carbohydrates. Of the 8% nutrients of watermelon, 7.55g consists of carbohydrates.

The watermelon pulp is very low in fiber, containing only 0.95g. The other 7.15g are composed of net carbs.

One average serving size of watermelon provides 20g of net carbs.

The net carb content contains mainly sugars, such as fructose, glucose, sucrose, and only a small amount of maltose.

Carbohydrate type breakdown

19% 25% 54%
Starch: 0 g
Sucrose: 1.21 g
Glucose: 1.58 g
Fructose: 3.36 g
Lactose: 0 g
Maltose: 0.06 g
Galactose: 0 g

Protein and Fats

The protein concentration is deficient, with only 0.6g in 100g of watermelon. It also has an insignificant amount of fats; therefore, it is low in saturated fats and has no trans fats or cholesterol.

In protein quality breakdown, out of all the essential amino acids, tryptophan, threonine, and lysine are contained in equal amounts and have the highest concentration. The remaining essential amino acids are equal, but each makes up only 1% of the protein.

Seeds and Rind

Watermelon seeds have a lot more protein (around 8%) and fats (around 17%), as well as fiber (around 40%) and calories; however, it is much more challenging to consume 100g of watermelon seeds (3).

Another study about the nutritional values of watermelon seeds found very different numbers, putting protein at around 34%, 32% fat, 27% carbohydrates, and 0.1% dietary fiber (4).

The watermelon rind is rich in a non-essential amino acid called citrulline, also found in the flesh. Red flesh watermelon has slightly less citrulline than yellow and orange flesh watermelons (5).


Watermelon is an excellent source of vitamin A and vitamin C. It falls in the top 26% of foods as a source of these vitamins.

It also contains low to moderate amounts of B complex vitamins, particularly B1, B2, B3, B5, and B6. It is low in vitamin K and vitamin E.

Watermelons are absent in vitamin D, vitamin B12, and vitamin B9.

Watermelon seeds are rich in vitamin E and vitamin C (4). They are also much higher in vitamin B3 than flesh (6).

The rind of a watermelon is richer in vitamin A and contains high amounts of vitamin C (6).

Vitamin coverage chart

Vitamin A Vitamin E Vitamin D Vitamin C Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Folate Vitamin B12 Choline Vitamin K 35% 1% 0% 27% 9% 5% 4% 14% 11% 3% 0% 3% 1%
Vitamin A: 569 IU of 5,000 IU 11%
Vitamin E : 0.05 mg of 15 mg 0%
Vitamin D: 0 µg of 10 µg 0%
Vitamin C: 8.1 mg of 90 mg 9%
Vitamin B1: 0.033 mg of 1 mg 3%
Vitamin B2: 0.021 mg of 1 mg 2%
Vitamin B3: 0.178 mg of 16 mg 1%
Vitamin B5: 0.221 mg of 5 mg 4%
Vitamin B6: 0.045 mg of 1 mg 3%
Folate: 3 µg of 400 µg 1%
Vitamin B12: 0 µg of 2 µg 0%
Choline: 4.1 mg of 550 mg 1%
Vitamin K: 0.1 µg of 120 µg 0%


Watermelon alone is not a great source of minerals. However, watermelon pulp is relatively high in potassium, manganese, magnesium, calcium, and phosphorus.

It has moderate amounts of copper, iron, zinc, selenium, and choline. It is deficient in sodium.

Watermelon seeds also contain appreciable minerals: calcium, phosphorus, magnesium, sodium, potassium, and zinc (3).

Mineral coverage chart

Calcium Iron Magnesium Phosphorus Potassium Sodium Zinc Copper Manganese Selenium 3% 9% 8% 5% 10% 1% 3% 14% 5% 3%
Calcium: 7 mg of 1,000 mg 1%
Iron: 0.24 mg of 8 mg 3%
Magnesium: 10 mg of 420 mg 2%
Phosphorus: 11 mg of 700 mg 2%
Potassium: 112 mg of 3,400 mg 3%
Sodium: 1 mg of 2,300 mg 0%
Zinc: 0.1 mg of 11 mg 1%
Copper: 0.042 mg of 1 mg 5%
Manganese: 0.038 mg of 2 mg 2%
Selenium: 0.4 µg of 55 µg 1%

Glycemic Index (GI)

Based on the numbers from The International Tables of Glycemic Index, the glycemic index of a raw watermelon from Australia containing 10g of carbohydrates is 80±3. In parallel with that, a raw watermelon containing 25g of carbohydrates has a GI of 72±13. The difference in carbohydrate concentration is based on the season and the growing environment.

Based on these numbers, the average GI of watermelon is 76 (7).

Despite the high GI, watermelon’s glycemic load of 4-6 is low, meaning one serving of watermelon contains only 6g of carbohydrates.

According to Harvard Health Publishing, a raw watermelon has a GI of 76±4 (8).

Another study has shown different numbers for the GI of a watermelon. They found red-fleshed seedless watermelon to have a GI of 51±2. Red-fleshed seeded watermelon has a slightly lower GI of 48±1, with yellow-fleshed watermelon having an even lower GI of 47±2. This study has shown no difference between the GI of a red-fleshed seedless watermelon and the juice extracted from it. (9)

Other research has shown that watermelon from the Philippines has a GI of 48±4 and Malaysian watermelon has a GI of 55±3 (10, 11).

A watermelon’s glycemic index can be high or low, depending on the maturity stage, fiber and fat content, processing and treatment of the sample, and other factors.

Despite all these positive effects, people with diabetes are advised to moderate watermelon intake and combine high-sugar fruits with healthy fats, fiber, and proteins to slow glucose absorption into the bloodstream.

You can find GI values for other foods by visiting our glycemic index chart page.


Oxalates are famous antinutrients in fruits and vegetables that may bind to calcium ions in organisms and result in kidney stones. Watermelon oxalate content is negligible: it contains 0mg of oxalates per serving size (29). However, watermelon seeds contain approximately 0.5g per 100g (30).


FODMAPs are nutrients, especially carbohydrates, that may trigger irritable bowel syndrome. Fructose is such a nutrient contained in watermelon. There is 3.36g of fructose per 100g of watermelon. Hence, people intolerant to FODMAPs should avoid watermelon consumption; otherwise, it may result in gas, stomach ache, bloating, and diarrhea. 


Watermelon is rich in different types of phytochemicals, such as antioxidant vitamin C, flavonoids, phenolics, etc. However, carotenoids like lycopene and beta-carotene are present in the highest quantities. 

Lycopene is a natural antioxidant that fights oxidative stress, cancer, diabetes, and other conditions (31). Fresh watermelon contains approximately 7.2mg of it per 100g

Beta-carotene is a carotenoid, an antioxidant that helps prevent oxidative damage, cognitive decline, and cancer formation. Red watermelon provides 4.42mg of it per 100g (32).

Health Impact


Watermelons have an average glycemic index of 76, but that number can change depending on the maturity and carbohydrate composition of the watermelon.

Watermelons get their bright color from a carotenoid called lycopene. This compound has gained attention from scientists due to its bioavailability and high absorption levels in a watermelon. It has been proven to positively affect the cardiovascular system while also playing a role in defending the organism from diseases such as diabetes and cancer (12).

Another essential component of a watermelon is the non-essential amino acid called L-citrulline, which has been studied as a potential non-pharmaceutical treatment for insulin resistance (13). L-citrulline is contained in incredibly high concentrations in the rind of a watermelon.

Once again, the consumption of watermelon is advised alongside healthy fats, fiber, and protein, such as nuts, for people with diabetic conditions to slow the absorption of glucose.


The amino acid L-citrulline can protect the organism not only from diabetes but can also have a positive therapeutic effect on people with high blood pressure or other cardiovascular diseases (13).

A study has shown that it can effectively reduce the extent of cardiovascular disorders (12).


Watermelon allergies are rare but can still occur in children and adults.

Three major allergens have been described in watermelons: malate dehydrogenase, triosephosphate isomerase, and profilin. Among watermelon-allergic patients, the frequencies of sensitization to these compounds are 96, 78, and 56 percent respectively (14).

These allergens usually cause oral allergy syndrome as the primary manifestation. It commonly presents with immediate swelling and an itching sensation in the mouth after consuming the food allergen (15).

The protein profilin can also be found in other fruits, such as melons and oranges․


As stated, the carotenoid lycopene can also have anti-carcinogenic qualities (12).

A group of compounds in which the watermelon rind is also rich in polysaccharides, such as arabinogalactan, galactose, arabinose, rhamnose, and others. These polysaccharides are known for their antiproliferative and antioxidant properties. The antitumor activity of watermelon rind has a significant cytotoxic ability against laryngeal carcinomatous cells (16).

Watermelon rind is also rich in anthocyanin and flavonoids, known for their antioxidant, anti-inflammatory, and anticancer qualities (17).


The antioxidant lycopene has also been proven to potentially reduce the development of pre-eclampsia and intrauterine growth retardation in first-time pregnant women (18).

Watermelon can be advised to patients with hyperemesis gravidarum, a pregnancy complication characterized by severe nausea and vomiting, as the high water content can help stay hydrated (19).

Urinary System

Watermelon pulp is known to have protective properties in chronic kidney failure and the potential ability to clear urine. It has been proven to possess significant anti-urolithic and diuretic activities to help people with bladder or urinary tract issues (20).

Watermelon Diet

As the name suggests, a watermelon diet is one during which you only eat watermelon. The high water content in watermelon makes this more of a cleanse than a diet.

Daily consumption of watermelon can reduce body weight, body mass index, and blood pressure, as well as improve some factors associated with obesity and being overweight. The mechanism for this action is watermelon’s ability to increase perceived satiety and moderate postprandial glucose and insulin response (21).

As a fruit, watermelon has a high density of water with low caloric intake, making it a perfect snack for people trying to lose weight. We’ve already talked about the health benefits of watermelon consumption; however, the watermelon diet is a radical form of dieting. Due to the lack of protein, fats cannot be recommended to children, pregnant women, and people with diabetes or malnourishment.

Watermelon in Diets

KetoThe keto diet allows an average of 10-20% of your daily caloric intake to be carbohydrates (22). A 100g watermelon contains only 8g of carbohydrates; therefore, watermelons can be consumed during a keto diet with careful management of the carbohydrate intake.
DASHWatermelons are suitable for the DASH diet due to their low sodium and high potassium, magnesium, and fiber concentrations. You can have 4-5 servings of fruits each day (23).
AtkinsYou can have watermelon if you’re on the third or fourth phases of the Atkins 20 diet or the Atkins 40 diet. However, a cup of watermelon contains 11g of carbohydrates, so you have to eat it in moderation (24).
MediterraneanThe Mediterranean diet emphasizes using fruits and vegetables in your eating plan. Watermelon suits this diet perfectly. The Mediterranean watermelon salad is a well-known recipe.
PaleoEven though prehistoric people probably did not eat watermelons, a moderate amount can be acceptable during a paleo diet. It is one of the few sweet fruits that can be used on a paleo diet (25).
Vegan/ Vegetarian/ PescetarianSince watermelons are plant species, you can naturally eat them on these diets.
DukanYou cannot eat watermelons or fruits in general during the Attack and Cruise phases. You can add watermelon into your diet during the Consolidation phase, but only one serving a day. You can have moderate amounts of watermelon throughout the Stabilization phase (26). Watermelon overall is considered to be a Dukan-friendly food, depending on the phase you’re in (27).
Intermittent FastingTraditionally you should abstain from watermelon during the fasting period and eat it during the eating periods. However, some believe you can occasionally break the fast with a low-calorie seasonal fruit, like watermelon.
Low Fat & Low CalorieWatermelon has almost no fat and since over 90 percent of it is water, it is one of the best fruits to eat during a low-fat or a low-calorie diet. A 100g serving of watermelon has only 30 calories.
Low CarbWatermelon can be a great option to satisfy your sweet cravings during a low-carb diet, but only in moderation. Keep in mind an average serving of watermelon contains 20g of net carbs.
Anti InflammatoryWatermelon is great for an anti-inflammatory diet due to its properties gained from lycopene, anthocyanin, and flavonoids (12, 17).
BRATIf you are following the BRAT diet for a limited amount of time, you can add watermelon as bland food since it is an excellent source of hydration. However, you have to moderate your intake as large amounts of lycopene consumption can cause diarrhea (28).


  1. The 5,000-Year Secret History of the Watermelon
  8. Glycemic index for 60+ foods
Article author photo Victoria Mazmanyan
Education: General Medicine at YSMU
Last updated: October 12, 2023
Medically reviewed by Ani Harutyunyan

Important nutritional characteristics for Watermelon

Glycemic index ⓘ Source:
Check out our Glycemic index chart page for the full list.
76 (high)
Glycemic load 15 (medium)
Insulin index ⓘ Falls in a large range 84
Calories ⓘ Calories per 100-gram serving 30
Net Carbs ⓘ Net Carbs = Total Carbohydrates – Fiber – Sugar Alcohols 7.15 grams
Serving Size ⓘ Serving sizes are taken from FDA's Reference Amounts Customarily Consumed (RACCs) 1 NLEA serving (280 grams)
Acidity (Based on PRAL) ⓘ PRAL (Potential renal acid load) is calculated using a formula. On the PRAL scale the higher the positive value, the more is the acidifying effect on the body. The lower the negative value, the higher the alkalinity of the food. 0 is neutral. -2 (alkaline)
Oxalates ⓘ 0mg
TOP 23% Vitamin A ⓘHigher in Vitamin A content than 77% of foods
TOP 26% Vitamin C ⓘHigher in Vitamin C content than 74% of foods
TOP 38% Cryptoxanthin, beta ⓘHigher in Cryptoxanthin, beta content than 62% of foods
TOP 38% Lycopene ⓘHigher in Lycopene content than 62% of foods
TOP 40% Vitamin A RAE ⓘHigher in Vitamin A RAE content than 60% of foods

Watermelon calories (kcal)

Serving Size Calories Weight
Calories in 100 grams 30
Calories in 1 cup, balls 46 154 g
Calories in 1 cup, diced 46 152 g
Calories in 10 watermelon balls 37 122 g
Calories in 1 NLEA serving 84 280 g

Watermelon Glycemic index (GI)

Check out our Glycemic index chart page for the full list.

Watermelon Glycemic load (GL)


Mineral chart - relative view

0.038 mg
TOP 69%
112 mg
TOP 80%
0.042 mg
TOP 84%
10 mg
TOP 84%
7 mg
TOP 85%
0.24 mg
TOP 87%
0.1 mg
TOP 91%
0.4 µg
TOP 91%
11 mg
TOP 92%
1 mg
TOP 98%

Vitamin chart - relative view

Vitamin A
569 IU
TOP 23%
Vitamin C
8.1 mg
TOP 26%
Vitamin B5
0.221 mg
TOP 79%
Vitamin B1
0.033 mg
TOP 80%
Vitamin B6
0.045 mg
TOP 80%
3 µg
TOP 87%
Vitamin K
0.1 µg
TOP 88%
Vitamin B3
0.178 mg
TOP 88%
Vitamin B2
0.021 mg
TOP 90%
Vitamin E
0.05 mg
TOP 91%
4.1 mg
TOP 93%
Vitamin D
0 µg
TOP 100%
Vitamin B12
0 µg
TOP 100%

Protein quality breakdown

Tryptophan Threonine Isoleucine Leucine Lysine Methionine Phenylalanine Valine Histidine 8% 8% 5% 2% 9% 2% 3% 3% 3%
Tryptophan: 7 mg of 280 mg 3%
Threonine: 27 mg of 1,050 mg 3%
Isoleucine: 19 mg of 1,400 mg 1%
Leucine: 18 mg of 2,730 mg 1%
Lysine: 62 mg of 2,100 mg 3%
Methionine: 6 mg of 1,050 mg 1%
Phenylalanine: 15 mg of 1,750 mg 1%
Valine: 16 mg of 1,820 mg 1%
Histidine: 6 mg of 700 mg 1%

Fat type information

16% 36% 49%
Saturated Fat: 0.016 g
Monounsaturated Fat: 0.037 g
Polyunsaturated fat: 0.05 g

Fiber content ratio for Watermelon

82% 5% 13%
Sugar: 6.2 g
Fiber: 0.4 g
Other: 0.95 g

All nutrients for Watermelon per 100g

Nutrient Value DV% In TOP % of foods Comparison
Calories 30kcal 2% 94% 1.6 times less than OrangeOrange
Protein 0.61g 1% 89% 4.6 times less than BroccoliBroccoli
Fats 0.15g 0% 90% 222.1 times less than Cheddar CheeseCheddar Cheese
Vitamin C 8.1mg 9% 26% 6.5 times less than LemonLemon
Net carbs 7.15g N/A 52% 7.6 times less than ChocolateChocolate
Carbs 7.55g 3% 54% 3.7 times less than RiceRice
Cholesterol 0mg 0% 100% N/AEgg
Vitamin D 0µg 0% 100% N/AEgg
Iron 0.24mg 3% 87% 10.8 times less than Beef broiledBeef broiled
Calcium 7mg 1% 85% 17.9 times less than MilkMilk
Potassium 112mg 3% 80% 1.3 times less than CucumberCucumber
Magnesium 10mg 2% 84% 14 times less than AlmondAlmond
Sugar 6.2g N/A 46% 1.4 times less than Coca-ColaCoca-Cola
Fiber 0.4g 2% 57% 6 times less than OrangeOrange
Copper 0.04mg 5% 84% 3.4 times less than ShiitakeShiitake
Zinc 0.1mg 1% 91% 63.1 times less than Beef broiledBeef broiled
Starch 0g 0% 100% N/APotato
Phosphorus 11mg 2% 92% 16.5 times less than Chicken meatChicken meat
Sodium 1mg 0% 98% 490 times less than White BreadWhite Bread
Vitamin A 569IU 11% 23% 29.4 times less than CarrotCarrot
Vitamin A RAE 28µg 3% 40%
Vitamin E 0.05mg 0% 91% 29.2 times less than KiwifruitKiwifruit
Selenium 0.4µg 1% 91%
Manganese 0.04mg 2% 69%
Vitamin B1 0.03mg 3% 80% 8.1 times less than Pea rawPea raw
Vitamin B2 0.02mg 2% 90% 6.2 times less than AvocadoAvocado
Vitamin B3 0.18mg 1% 88% 53.8 times less than Turkey meatTurkey meat
Vitamin B5 0.22mg 4% 79% 5.1 times less than Sunflower seedSunflower seed
Vitamin B6 0.05mg 3% 80% 2.6 times less than OatOat
Vitamin B12 0µg 0% 100% N/APork
Vitamin K 0.1µg 0% 88% 1016 times less than BroccoliBroccoli
Trans Fat 0g N/A 100% N/AMargarine
Folate 3µg 1% 87% 20.3 times less than Brussels sproutBrussels sprout
Saturated Fat 0.02g 0% 92% 368.4 times less than Beef broiledBeef broiled
Choline 4.1mg 1% 93%
Monounsaturated Fat 0.04g N/A 86% 264.8 times less than AvocadoAvocado
Polyunsaturated fat 0.05g N/A 90% 943.5 times less than WalnutWalnut
Tryptophan 0.01mg 0% 97% 43.6 times less than Chicken meatChicken meat
Threonine 0.03mg 0% 96% 26.7 times less than Beef broiledBeef broiled
Isoleucine 0.02mg 0% 97% 48.1 times less than Salmon rawSalmon raw
Leucine 0.02mg 0% 98% 135.1 times less than Tuna BluefinTuna Bluefin
Lysine 0.06mg 0% 94% 7.3 times less than TofuTofu
Methionine 0.01mg 0% 97% 16 times less than QuinoaQuinoa
Phenylalanine 0.02mg 0% 97% 44.5 times less than EggEgg
Valine 0.02mg 0% 98% 126.8 times less than Soybean rawSoybean raw
Histidine 0.01mg 0% 98% 124.8 times less than Turkey meatTurkey meat
Fructose 3.36g 4% 82% 1.8 times less than AppleApple
Omega-3 - EPA 0g N/A 100% N/ASalmon
Omega-3 - DHA 0g N/A 100% N/ASalmon
Omega-3 - DPA 0g N/A 100% N/ASalmon

Check out similar food or compare with current


Nutrition Facts
___servings per container
Serving Size ______________
Amount Per 100g
Calories 30
% Daily Value*
Total Fat 0g
Saturated Fat 0g
Trans Fat g
Cholesterol 0mg
Sodium 1mg
Total Carbohydrate 8g
Dietary Fiber 0g
Total Sugars g
Includes ? g Added Sugars
Protein 1g
Vitamin D 0mcg 0%

Calcium 7mg 1%

Iron 0mg 0%

Potassium 112mg 3%

The % Daily Value (DV) tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.

Health checks

Low in Cholesterol
 ⓘ Dietary cholesterol is not associated with an increased risk of coronary heart disease in healthy individuals. However, dietary cholesterol is common in foods that are high in harmful saturated fats.
No Trans Fats
 ⓘ Trans fat consumption increases the risk of cardiovascular disease and mortality by negatively affecting blood lipid levels.
Low in Saturated Fats
 ⓘ Saturated fat intake can raise total cholesterol and LDL (low-density lipoprotein) levels, leading to an increased risk of atherosclerosis. Dietary guidelines recommend limiting saturated fats to under 10% of calories a day.
Low in Sodium
 ⓘ Increased sodium consumption leads to elevated blood pressure.
Low in Sugars
 ⓘ While the consumption of moderate amounts of added sugars is not detrimental to health, an excessive intake can increase the risk of obesity, and therefore, diabetes.

Watermelon nutrition infographic

Watermelon nutrition infographic
Infographic link


All the values for which the sources are not specified explicitly are taken from FDA’s Food Central. The exact link to the food presented on this page can be found below.


Data provided by should be considered and used as information only. Please consult your physician before beginning any diet.