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    Fruit · Glycemic index

    Does watermelon spike blood sugar?

    Not much. Watermelon has a low GI of 50, and a 152 g serving (1 cup diced) has a low glycemic load of 6. Watermelon is about 91% water with under 8 g of carbohydrate per 100 g, so a cup of diced melon has a low glycemic load whichever GI figure you use.

    Key numbers

    Glycemic index
    50
    Low GI
    Glycemic load
    6
    Low GL
    Available carbs
    11 g
    0.6 g fiber
    Serving
    1 cup diced
    152 g · raw

    GI vs GL for watermelon

    The glycemic index (GI) compares how fast the carbohydrate in a food raises blood sugar against pure glucose (100), using a fixed amount of carbohydrate. The glycemic load (GL) adds the other half of the story — how much carbohydrate a normal serving actually contains: GI × available carbs Ă· 100. For watermelon: 50 × 11 g Ă· 100 ≈ 6.

    That figure is an average reported in the 2021 international GI tables (“Watermelon, mean of four foods”). Older tables listed watermelon as high GI because two Australian tests from 1994 and 2003 found 72 and 80. Newer ISO-standard tests from Malaysia (47 to 55) are why the 2021 average is much lower.

    Eating a different amount? Work out the glycemic load of your portion.

    How to eat watermelon with less of a spike

    • Stick to a cup or two at a time; one USDA wedge (1/16 of a melon) is nearly two cups' worth.
    • Eat it with a handful of nuts or some feta rather than on its own.
    • Choose the fruit over watermelon drinks or slushies with added sugar.

    Other low-GI choices

    Compare with

    See all 67 foods in the glycemic index table

    Frequently asked questions

    What is the glycemic index of watermelon?

    Watermelon has a glycemic index of 50, which is low. That figure is an average reported in the 2021 international GI tables (“Watermelon, mean of four foods”). A 152 g serving (1 cup diced) contains about 11 g of available carbohydrate, giving a glycemic load of 6 (low).

    Is watermelon good for prediabetes?

    Watermelon is a good summer fruit for prediabetes in normal portions. A cup of diced melon has a low glycemic load; working through half a melon in one sitting is another matter.

    Why do some lists say watermelon has a GI of 72 or 80?

    Those figures come from two older Australian tests. The 2021 international tables average four newer ISO-standard tests at 50. Either way, watermelon's glycemic load per cup is low because it contains little carbohydrate.

    Sources

    GI values come from the international GI tables; carbohydrate and fiber per serving are calculated from USDA FoodData Central.

    1. Atkinson FS, Brand-Miller JC, Foster-Powell K, Buyken AE, Goletzke J. International tables of glycemic index and glycemic load values 2021: a systematic review. Am J Clin Nutr. 2021;114(5):1625–1632, Supplemental Table 1
    2. USDA FoodData Central, FDC ID 167765: Watermelon, raw
    3. The University of Sydney, Glycemic Index Research Service — GI database search
    4. Atkinson FS, Foster-Powell K, Brand-Miller JC. International tables of glycemic index and glycemic load values: 2008 — online appendix, Table A1

    Data last checked .

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