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Carbs in watermelon

Per 1 cup diced (152 g)

12g

Total carbs

1g

Fiber

11g

Net carbs

9g

Sugars

1g

Protein

0g

Fat

46

Calories

76high

Glycemic index

8low

Glycemic load

Values are typical for the stated serving, consistent with USDA FoodData Central; brands and preparations vary. GI reference: glucose = 100.

What watermelon actually does

Watermelon is the textbook case of why GI and GL are different: its GI is a sky-high 76, but a cup is over 90 percent water and only carries about 12 g of carbs, so the glycemic load is genuinely low. The result is a fast but small bump — quick up, quick down. The problem is nobody eats one cup of watermelon at a barbecue. Three or four cups, easy to put away on a hot day, turns a low-load snack into a 35–45 g fast carb hit, and that shows up on the curve exactly the way you would expect.

Quick rise, often within 30–45 minutes — but small per cup, so the peak stays modest.

Worth trying

Portion is the entire game here — a cup or two is a gentle snack, a quarter melon is not. Pairing it with something salty and fatty like feta slows it a touch.

Fast, sharp rise — often within 30–45 minutes. Schematic shape, not measured data — your curve is your own.

Common questions

Is watermelon bad for diabetics because of its high GI?

Less bad than the GI suggests. GI measures speed, not amount — and a cup of watermelon only has about 11 g of net carbs, giving it a low glycemic load. A sensible portion produces a quick but small bump. The risk is volume: it is very easy to eat four cups without noticing.

How much watermelon can I eat with diabetes?

Each cup of diced watermelon is roughly 12 g of carbs, so count cups like you would count anything else. Two cups is about 24 g — a real but manageable amount for most meals or snacks. Your own CGM response at a known portion is the best guide; targets are worth discussing with your care team.

Related foods

🍌 Banana · 27g🍎 Apple · 25g🍇 Grapes · 27g🍓 Strawberries · 12gFull library →

Real quick — we’re not your doctor. Everything on this page is general information, not medical advice, and diabetes is deeply individual. CarbLens AI never recommends insulin doses. Use what you learn here to have smarter conversations with your care team.

See what watermelon does to YOUR blood sugar.

Averages are averages. CarbLens AI logs your meal and shows the 3-hour curve your own body produced.

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