Ask the Sports Dietitian & Fitness Coach

Questions From the Community

Q: Is watermelon actually hydrating enough to count toward my daily fluid intake?

A: Yes, and there is research behind it. Watermelon is approximately 92% water by weight, making it one of the most water-dense whole foods you can eat. The Mayo Clinic confirms fluid from food counts toward your daily hydration needs, and the CDC agrees total water intake includes water consumed from food sources.¹² A 2-cup serving of watermelon contributes to your daily fluid goals while also containing natural carbohydrates and potassium (314mg per 2-cup serving).³ So yes, every slice counts.

Q: When is the best time to eat watermelon if I am active?

A: Watermelon works well at multiple points around activity. Before a workout, it provides natural carbohydrates for fuel. During activity, frozen watermelon cubes are easy to carry and are refreshing mid-effort. After exercise, watermelon provides fluid, carbohydrates, and antioxidant compounds to support recovery. The short answer: any time is a good time.

Q: Can watermelon replace my sports drink or serve as my sole source of rehydration after a workout?

A: Watermelon can meaningfully support your hydration and fueling needs around activity, but it works best as part of a complete strategy rather than a standalone replacement. Research has found watermelon can support the carbohydrate and fluid needs of prolonged exercise comparably to standard carbohydrate beverages.⁴ A 2-cup serving provides approximately 8 to 10 ounces of fluid and 314mg of potassium, per 2-cup serving, which is a practical contribution for light to moderate activity. For longer or more intense sessions where sweat losses are higher, pair watermelon with additional water and a sodium source to support complete rehydration. Where watermelon has a clear advantage over conventional sports drinks is in its antioxidant compounds including lycopene (12.7mg per 2-cup serving, the highest of any fresh fruit or vegetable^8,9), vitamin C (23mg, 25% Daily Value per 2-cup serving⁸), and beta-carotene expressed as vitamin A (8% Daily Value per 2-cup serving⁸). Individual needs vary based on intensity, duration, and sweat rate. As always, consult with a registered dietitian for personalized guidance.

Q: Is watermelon available year-round?

A: Yes. This is one of the most common misconceptions I hear. Watermelon is available year-round at most grocery stores across the United States, not just in the summer. While peak domestic harvest runs from late spring through early fall, grocery stores source watermelon from domestic and international growers year-round. You can find whole watermelons and pre-cut watermelon in the produce section in January just as easily as in July. And if you want to extend it even further, cut watermelon into cubes, freeze it in zip-lock bags, and you have it ready for smoothies, the electrolyte concentrate, and the Tajin ice cream all year long.

Q: Is the rind edible? What do I do with it?

A: Absolutely edible, and most people throw away something genuinely useful. The white part of the watermelon rind is mild in flavor, low in calories at approximately 15 to 20 calories per cup, and contains 4mg of Vitamin C per cup.³ It has been eaten for centuries in many cultures. The easiest way to use it is to shred it like coleslaw, pickle it, or stir-fry it. The Watermelon Rind Slaw recipe in this hub is a good place to start. Store raw rind in the refrigerator for up to five days and treat it like any other mild vegetable.

Q: How long can I keep watermelon frozen?

A: Per USDA FoodKeeper guidelines, frozen watermelon maintains best quality for eight to 12 months when stored in an airtight freezer bag at 0 degrees F or below. One important thing to know: because watermelon is 92% water, freezing changes the texture significantly. Thawed watermelon will be soft rather than crisp, making it ideal for blended uses like smoothies, the electrolyte concentrate, and the Tajin nice cream, but not for eating fresh. For best results, freeze in a single layer on a parchment-lined sheet pan first, then transfer to a freezer bag to prevent clumping.

Q: Are watermelon seeds nutritious? Should I be eating them?

A: Yes, and most people are missing out. Watermelon seed kernels (the inner white part not the black outer shell) are surprisingly nutrient-dense. A one-ounce serving of dried watermelon seed kernels contains approximately 8 grams of plant-based protein, about 35% of the Daily Value for magnesium, 2.9mg of zinc (26% DV), and 2mg of iron (11% DV).^10,11,12 Magnesium and zinc are nutrients found in watermelon seeds. Like other hard-shelled seeds, the outer coat resists digestion, so much of the seed can pass through largely intact when eaten whole.¹³ The seeds are best eaten roasted. Look for roasted watermelon seed kernels at health food stores or online for a practical, portable snack option.

Q: How do I consistently find a good watermelon?

A: A few reliable signs. First check the field spot, the creamy yellow patch on the underside. A deep yellow color means it ripened on the vine. Pale white or no field spot usually means it was picked early. Second, it should feel heavy for its size since that weight comes from water content. Third, look for a dull, not shiny, surface; a shiny watermelon is often underripe. Pre-cut watermelon at the grocery store should have vibrant deep red flesh. Pale or white streaks near the rind are a sign it was harvested before peak ripeness.¹⁴

Q: Does watermelon have any benefits for immune health?

A: A reasonable question, especially for athletes who train hard and know that intense exercise can temporarily affect immune function. Watermelon is an excellent source of vitamin C, containing 23mg, 25% of your Daily Value per 2-cup serving and vitamin A at 8% of your Daily Value per serving.⁸ Both are nutrients that have been studied in the context of immune health. Watermelon is not a treatment or prevention for illness; it is a whole food that contributes these nutrients as part of a balanced diet.

Q: How does watermelon fit into a performance nutrition plan?

A: Better than most people expect. Performance nutrition comes down to a few consistent priorities: fueling with carbohydrates before and during activity; rehydrating and replenishing after; and getting enough protein, vitamins, and minerals to support recovery over time. Watermelon contributes to several of those at once. A 2-cup serving provides 21 grams of natural carbohydrates for fuel, approximately 8 to 10 ounces of fluid, vitamin C at 25% of your Daily Value, and lycopene at 12.7mg, all from one whole food with no added ingredients.⁸ It is not a replacement for a complete nutrition plan. What it is, is a simple, accessible whole-food option that fits into almost any active lifestyle, any sport, any season, and any budget. I recommend it to recreational exercisers and serious athletes alike because the barrier to entry is zero.

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REFERENCES
¹Mayo Clinic. (2022). Water: How much should you drink every day? Mayo Clinic Healthy Lifestyle: Nutrition and Healthy Eating. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256
²Centers for Disease Control and Prevention (CDC). (2023). Fast Facts: Water Consumption. https://www.cdc.gov/nutrition/php/data-research/fast-facts-water-consumption.html
³U.S. Department of Agriculture (USDA). FoodData Central: Watermelon, raw. https://fdc.nal.usda.gov. Per 2-cup (280g) serving: water content ~92%, potassium 6% Daily Value, carbohydrates 21g.
⁴Shanely, R.A., Nieman, D.C., Perkins-Veazie, P., Henson, D.A., Meaney, M.P., Knab, A.M., & Cialdell-Kam, L. (2016). Comparison of watermelon and carbohydrate beverage on exercise-induced alterations in systemic inflammation, immune dysfunction, and plasma antioxidant capacity. Nutrients, 8(8), 518. PMID: 27556488. https://doi.org/10.3390/nu8080518
⁸U.S. Department of Agriculture, Agricultural Research Service. FoodData Central. Watermelon, raw (FDC ID: 2747675). Nutrient values per 2-cup serving (280g): lycopene 12.7mg, vitamin C 23mg (25% Daily Value), vitamin A/beta-carotene (8% Daily Value). https://fdc.nal.usda.gov/food-details/2747675/nutrients
⁹Tlili I, et al. Lycopene, a carotenoid with health protective properties. NJAS – Wageningen Journal of Life Sciences. 2020. PMC7698065. https://pmc.ncbi.nlm.nih.gov/articles/PMC7698065/
¹⁰U.S. Department of Agriculture, Agricultural Research Service. FoodData Central. Seeds, watermelon seed kernels, dried (FDC ID: 169407). https://fdc.nal.usda.gov/food-details/169407/nutrients
¹¹Tlili I, et al. Watermelon Nutritional Composition with a Focus on L-Citrulline and Its Cardioprotective Health Effects: A Narrative Review. Nutrients. 2025;17(20):3221. https://pmc.ncbi.nlm.nih.gov/articles/PMC12566930/
¹²Ogunlakin GO, et al. Nutritional composition and bioactive potential of watermelon seeds: a pathway to sustainable food and health innovation. Sustainable Food Technology. 2025;3:375–395. https://pubs.rsc.org/en/content/articlehtml/2025/fb/d4fb00335g
¹³Holland C, et al. Plant Cell Walls: Impact on Nutrient Bioaccessibility and Digestibility. Foods. 2020;9(2):201. https://pmc.ncbi.nlm.nih.gov/articles/PMC7074226/
¹⁴National Watermelon Promotion Board. How to Choose a Watermelon. https://www.watermelon.org/the-slice/how-to-choose-a-watermelon/