Hydrating smoothies

Watermelon cucumber smoothie

Name: Watermelon cucumber smoothie
Prep time: 5 min
Total time: 5 min
Yield: 2 servings
Cuisine: Mexican
Ingredients: 300 g (2 cups) watermelon, cubed, seeds removed; 100 g (about half) cucumber, roughly chopped; 1 tbsp (15 ml) fresh lime juice; 6–8 fresh mint leaves; 1 cup ice

For the mornings when drinking a glass of water feels like a chore but eating one does not.

Two glasses of pale pink watermelon smoothie garnished with mint, beside cubed watermelon on a board. — 🤖 This image was generated with AI, not photographed. We're working on sourcing real photography for these recipes.

Jump to the recipe ↓ ⏱ 5 min · 🥛 two glasses, about 300 ml each

Watermelon is 91% water and cucumber is 95%, so a smoothie made of nothing else is essentially water you chew. The difference is that it also brings the potassium and magnesium the fruit was already carrying, which plain water does not.

No milk, no yoghurt, no protein powder. Those all turn a hydrating drink into a small meal, which is fine but is a different job.

How to make it

Hands on: 5 min
Total: 5 min
Makes: 2 servings
Per glass: 55 kcal

Ingredients

300 g (2 cups) watermelon, cubed, seeds removed
100 g (about half) cucumber, roughly chopped
1 tbsp (15 ml) fresh lime juice
6–8 fresh mint leaves
1 cup ice

Method

Freeze the watermelon

If you have the foresight, freeze the watermelon cubes the night before and skip the ice. You get the same cold without watering it down.
Blend

Put everything in the blender and run it for 45–60 seconds, until there are no pale flecks of cucumber skin left.
Taste and adjust

Watermelons vary enormously in sweetness. Add more lime if it tastes flat, more mint if it tastes like nothing.
Serve immediately

It separates within about ten minutes. That is not spoilage — stir it and carry on — but it looks better drunk fresh.

Worth knowing

Do not peel the cucumber. The peel carries most of its potassium and all of its colour.
A blender is not strictly required — watermelon breaks down in a food processor or even a stick blender in a jug.

What it actually does for you

Calories: 55 kcal
Sugar: 10.2 g
Sodium: 3 mg
Potassium: 250 mg
Magnesium: 22 mg

The best potassium-per-calorie drink on this hub, and about 92% water by weight. The gap is sodium — 3 mg a glass is nothing, so this rehydrates well after a warm day but not after a sweaty one. Add the pinch of salt from the variations if you have actually been sweating.

How this was worked out: Summed from USDA FoodData Central for raw watermelon (300 g: 90 kcal, 18.3 g sugar, 336 mg potassium, 30 mg magnesium) and raw cucumber with peel (100 g: 15 kcal, 1.7 g sugar, 147 mg potassium, 13 mg magnesium), plus 15 ml lime juice, divided by two servings. Ice is excluded. Figures are approximate — watermelon sugar varies by a lot.

Variations

Add a pinch of salt to turn it into a genuine post-workout drink; 1/8 tsp adds about 150 mg sodium per glass.
Swap the mint for basil and the lime for lemon for a less sweet version.
Blend in 100 g of strawberries if the watermelon turned out bland.

Making it is the easy part

Remembering to drink it is the hard part. Honk watches your webcam with on-device AI and honks until you do, as gently or as loudly as you like.

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Questions

Is a smoothie as hydrating as water?

This one is close. It is about 92% water by weight, and the potassium and magnesium in the fruit help slightly with fluid retention. A thick smoothie with banana, oats or yoghurt is a different story — that is food, and it hydrates you much less per glass.

Can you make it the night before?

You can, but it separates and dulls. If you want it ready in the morning, freeze the prepped fruit in a bag instead and blend it when you want it — that takes ninety seconds.

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