Watermelon is one of nature’s most refreshing and hydrating fruits, packed with essential nutrients while remaining remarkably low in calories. This naturally sweet fruit has become a summer staple for good reason—it offers impressive health benefits backed by scientific research.
Whether you’re counting calories, managing your blood pressure, or simply looking for a nutritious snack, understanding watermelon’s nutritional profile can help you make informed dietary choices. This comprehensive guide explores everything you need to know about watermelon calories, nutrients, and health benefits.
How Many Calories Are in Watermelon?
Watermelon is exceptionally low in calories, making it an excellent choice for weight management and healthy snacking. The calorie content varies based on portion size:
- Per 100 grams (2/3 cup): 30 calories
- Per cup (152 grams diced): 46 calories
- Per wedge (286 grams or 1/16 of melon): 86 calories
- Per whole melon (approximately 10 pounds): 1,360 calories
The remarkably low calorie count is primarily due to watermelon’s high water content—approximately 91% of its weight is water. This unique composition allows you to enjoy a satisfying, sweet treat without consuming excessive calories.
Complete Watermelon Nutrition Facts
Beyond its low calorie content, watermelon provides a variety of essential nutrients. Here’s the complete nutritional breakdown for 100 grams (2/3 cup) of raw watermelon:
- Water: 91 grams
- Protein: 0.6 grams
- Carbohydrates: 7.6 grams
- Natural sugars: 6.2 grams
- Dietary fiber: 0.4 grams
- Fat: 0.2 grams
Macronutrient Composition
Watermelon is primarily composed of water and carbohydrates, with minimal protein and virtually no fat. The carbohydrates consist mainly of simple sugars including glucose, fructose, and sucrose, which provide the fruit’s natural sweetness.
While watermelon has a high glycemic index (ranging from 72-80), the actual glycemic load per serving is relatively low due to the small amount of carbohydrates in each portion. This means that eating watermelon typically won’t cause dramatic spikes in blood sugar levels for most people.
Vitamins and Minerals in Watermelon
Watermelon contains several important vitamins and minerals that contribute to overall health:
Vitamin C
Watermelon provides a good amount of vitamin C, a powerful antioxidant that supports immune function, promotes healthy skin, and aids in wound healing. One cup of watermelon delivers approximately 21% of the daily recommended intake.
Vitamin A (Beta Carotene)
The red flesh of watermelon contains beta carotene, which your body converts into vitamin A. This nutrient is essential for eye health, immune function, and cell growth.
Potassium
This essential mineral plays a crucial role in blood pressure regulation, heart health, and proper muscle function. Watermelon provides approximately 112 mg of potassium per 100-gram serving.
Vitamin B5 (Pantothenic Acid)
Present in nearly all foods, vitamin B5 is important for energy metabolism and the synthesis of various compounds in the body.
Copper
Watermelon contains small amounts of copper, a mineral important for iron metabolism, nervous system function, and the formation of red blood cells.
Powerful Plant Compounds in Watermelon
What truly sets watermelon apart from other fruits are its unique plant compounds, particularly citrulline and lycopene.
Citrulline: A Unique Amino Acid
Watermelon is the richest known natural source of citrulline, an amino acid with remarkable health benefits. The highest concentrations are found in the white rind surrounding the red flesh.
Once consumed, citrulline is converted in your body to arginine, another amino acid. Together, these compounds:
- Support the production of nitric oxide
- Help relax and dilate blood vessels
- May lower blood pressure
- Support wound healing
- Play roles in immune system function
Research indicates that watermelon juice can significantly increase blood levels of both citrulline and arginine, making it an effective natural source of these beneficial compounds.
Lycopene: A Powerful Antioxidant
Lycopene is the carotenoid pigment responsible for watermelon’s vibrant red color. Remarkably, fresh watermelon contains more lycopene per serving (4,532 micrograms per 100 grams) than fresh tomatoes (2,573 micrograms per 100 grams).
This powerful antioxidant has been extensively studied for its potential health benefits, including:
- Protection against oxidative stress and cell damage
- Support for heart health
- Potential cancer-protective properties
- Skin protection from UV damage
Studies demonstrate that consuming watermelon juice effectively raises blood levels of both lycopene and beta carotene.
Evidence-Based Health Benefits of Watermelon
Supports Healthy Blood Pressure
High blood pressure represents a significant risk factor for heart disease and stroke. The citrulline in watermelon may help manage blood pressure naturally.
When citrulline converts to arginine, it facilitates nitric oxide production. Nitric oxide acts as a vasodilator, causing blood vessels to relax and widen. This process can lead to reduced blood pressure and improved blood flow.
Multiple studies have examined watermelon supplementation in individuals with elevated blood pressure, with several showing promising results in reducing both systolic and diastolic blood pressure readings and arterial stiffness.
May Improve Metabolic Health
Insulin resistance—a condition where cells don’t respond properly to insulin—is a key factor in metabolic syndrome and type 2 diabetes development. Some research suggests that watermelon juice and its arginine content may help improve insulin sensitivity.
While more research is needed, these preliminary findings suggest watermelon could play a supportive role in metabolic health when consumed as part of a balanced diet.
Reduces Exercise-Related Muscle Soreness
Athletes and fitness enthusiasts may benefit from watermelon’s effects on exercise recovery. Research has examined whether watermelon juice or citrulline supplementation can reduce muscle soreness after intense workouts.
One study found that athletes who consumed watermelon juice before exercise experienced less muscle soreness 24 hours later compared to those who didn’t. The citrulline content may improve blood flow to muscles and reduce the buildup of lactic acid.
Results on exercise performance are mixed, with some studies showing improvements in untrained individuals but less effect in well-trained athletes.
Promotes Hydration
With its 91% water content, watermelon is an excellent food for maintaining proper hydration, especially during hot weather or after physical activity. Adequate hydration supports virtually every bodily function, from temperature regulation to nutrient transport.
Provides Antioxidant Protection
The combination of vitamin C, lycopene, and other antioxidants in watermelon helps protect your cells from oxidative damage caused by free radicals. This protection may reduce the risk of chronic diseases and support healthy aging.
Potential Concerns and Considerations
FODMAP Content and Digestive Sensitivity
Watermelon contains relatively high amounts of fructose, a type of sugar classified as a FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). Some individuals, particularly those with irritable bowel syndrome (IBS) or fructose malabsorption, may experience digestive discomfort after eating watermelon.
Symptoms may include:
- Bloating
- Gas
- Abdominal cramps
- Diarrhea
- Constipation
If you’re sensitive to FODMAPs, consider limiting portion sizes or avoiding watermelon during elimination phases of a low-FODMAP diet.
Allergic Reactions
While rare, watermelon allergies can occur. They’re often associated with oral allergy syndrome in people who are sensitive to certain pollens, particularly ragweed pollen.
Symptoms typically include:
- Itching or tingling in the mouth and throat
- Swelling of lips, tongue, or throat
- Itching in the ears
If you experience these symptoms after eating watermelon, consult with a healthcare provider or allergist.
Blood Sugar Considerations
Despite watermelon’s high glycemic index, its low carbohydrate content per serving means it has a relatively low glycemic load. However, individuals with diabetes should still monitor their blood sugar response and practice portion control. Consult with your healthcare provider about incorporating watermelon into your meal plan.
How to Select and Store Watermelon
Choosing a Ripe Watermelon
Select watermelons that are:
- Heavy for their size (indicating high water content)
- Firm and symmetrical
- Free from bruises, cuts, or dents
- Have a creamy yellow spot on the bottom (where it rested on the ground)
- Produce a hollow sound when tapped
Storage Tips
Store whole watermelons at room temperature for up to two weeks. Once cut, refrigerate watermelon in an airtight container for up to 3-5 days. You can also freeze cubed watermelon for up to 6-8 months, though the texture will change upon thawing—making frozen watermelon ideal for smoothies or blended drinks.
Creative Ways to Enjoy Watermelon
While most people enjoy watermelon fresh, there are numerous delicious ways to incorporate it into your diet:
- Fresh fruit salads: Combine with other fruits, mint, and a squeeze of lime
- Smoothies: Blend with ice, yogurt, and other fruits
- Watermelon juice: Blend and strain for a refreshing beverage
- Grilled watermelon: Caramelize the sugars for a unique flavor
- Savory salads: Pair with feta cheese, cucumber, and mint
- Frozen treats: Make watermelon popsicles or sorbet
- Agua fresca: Blend with water, lime juice, and a touch of sweetener
- Watermelon rind: Pickle the rind for a tangy treat that provides extra citrulline
Watermelon Compared to Other Fruits
How does watermelon stack up against other popular fruits in terms of calories and nutrition?
Per 100 grams:
- Watermelon: 30 calories
- Strawberries: 32 calories
- Cantaloupe: 34 calories
- Peaches: 39 calories
- Apples: 52 calories
- Grapes: 69 calories
- Bananas: 89 calories
Watermelon ranks among the lowest-calorie fruits while providing unique beneficial compounds not found in many other fruits.
Frequently Asked Questions
Is watermelon good for weight loss?
Yes, watermelon can support weight loss efforts due to its low calorie density and high water content. It provides volume and sweetness with minimal calories, helping you feel satisfied while maintaining a calorie deficit. However, portion control is still important.
Can diabetics eat watermelon?
People with diabetes can include watermelon in their diet in moderation. Despite its high glycemic index, the glycemic load per serving is relatively low. Monitor your blood sugar response and consult with your healthcare provider about appropriate portion sizes.
Is it true that watermelon is mostly water?
Yes, approximately 91% of watermelon’s weight comes from water, making it one of the most hydrating fruits available. This high water content contributes to its low calorie density.
Should I eat the watermelon rind?
The white rind is edible and actually contains the highest concentration of citrulline. While not as sweet as the flesh, it can be pickled, stir-fried, or blended into smoothies for added nutritional benefits.
How much watermelon should I eat per day?
There’s no specific limit, but 1-2 cups of diced watermelon per day is a reasonable serving size that provides health benefits without excessive sugar or FODMAP intake. Listen to your body and adjust based on your individual tolerance and nutritional needs.
The Bottom Line
Watermelon is a nutritional powerhouse that combines exceptional hydration with important vitamins, minerals, and unique plant compounds. With only 30 calories per 100 grams, it’s one of the lowest-calorie fruits available while still delivering natural sweetness and satisfaction.
The presence of citrulline and lycopene sets watermelon apart from other fruits, offering potential benefits for blood pressure management, metabolic health, and exercise recovery. These compounds, combined with vitamin C, potassium, and other nutrients, make watermelon an excellent addition to a balanced diet.
For most people, watermelon is a safe, delicious, and healthful food choice. Those with FODMAP sensitivities or specific medical conditions should consult with healthcare providers about appropriate portion sizes.
Whether you’re looking to manage your calorie intake, support your cardiovascular health, improve your workout recovery, or simply enjoy a refreshing treat, watermelon offers a perfect combination of taste and nutrition.
Sources:
- USDA FoodData Central – Watermelon, raw
- National Institutes of Health – Watermelon juice supplementation and metabolic response
- PubMed – Bioactive compounds in watermelon
- PubMed – Watermelon juice for muscle soreness relief
- PubMed – Watermelon juice increases lycopene and beta-carotene
- NIH Office of Dietary Supplements – Vitamin C
- NIH Office of Dietary Supplements – Potassium
- PubMed Central – Low FODMAP diet considerations
- PubMed Central – Fructose malabsorption and IBS
- PubMed Central – Lycopene sources and health benefits
⚕️ Medical Disclaimer
This content is for informational purposes only and does not constitute medical advice. The information provided has not been evaluated by the Food and Drug Administration (FDA) and is not intended to diagnose, treat, cure, or prevent any disease.
Always consult with a qualified healthcare professional before making any changes to your diet, taking supplements, or starting any health regimen. Individual results may vary.