Can You Eat Watermelon on a Low-Carb Diet?

Sliced Watermelon fresh on wooden board
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Watermelons are moderately high in sugar, but small amounts can be part of a low-carb diet. There are vitamins and nutrients in watermelon that make it a healthy choice for satisfying a sweet craving rather than simply empty calories. Here's a look at the carbohydrates in watermelon.

Carbohydrate and Fiber Counts

The key to enjoying watermelon on a low-carb diet is to watch your serving size.

The standard serving is one cup or 5 ounces and has 11 grams of net carbohydrates. For a wedge of watermelon, you should measure carefully as a wedge could be equal to several servings. A 1-inch wedge weighing 10 ounces is two servings.

Preparation of WatermelonCarbs, Fiber, and Calorie Counts
1/2 cup diced watermelon5.5 grams net carbohydrates, scant amount of fiber, 23 calories
1 cup diced watermelon11 grams net carbohydrates, 46 calories
1 wedge (1/16 average watermelon, 10 ounces)22 grams net carbohydrates, 1 gram fiber, 86 calories

Glycemic Index and Glycemic Load

The glycemic index of a food is an indicator of how much and how fast a food raises your blood sugar. The International Tables of Glycemic Index and Glycemic Load: 2008 shows the average glycemic index of watermelon as 76. 

The glycemic load of a food is related to the glycemic index but takes serving size into account. A glycemic load of 1 is the equivalent of eating 1 gram of glucose.

Watermelon looks much better by this measure, as there is little carbohydrate per serving.

Glycemic Load of Watermelon
1/2 cup of chopped watermelon: 1.5
1 wedge watermelon (1/16 average watermelon, 10 ounces):  6
1 serving (100 grams): 4

Health Benefits

Watermelon is a good source of vitamin C and vitamin A.

It is also an excellent source of lycopene, a phytonutrient that studies show can be helpful in maintaining cardiovascular health and possibly bone health. Other phytonutrients in watermelon include flavonoids, carotenoids, and triterpenoids, which have anti-inflammatory and antioxidant benefits. A fully ripe red watermelon contains higher levels of these nutrients than less-ripe pink watermelon.

The amino acid citrulline is found in high concentrations in watermelon. It is marketed as a nutritional supplement for various purported benefits, but the amount in found in watermelon may not equal the concentration sold in capsule form.

The watermelon rind contains significant amounts of nutrients, including citrulline, and lower sugar content. Unfortunately, pickled rind in most cases is made from a recipe that calls for the addition of a large amount of sugar, which wouldn't be appropriate on a low-carb diet.

Like the name suggests, watermelon is mainly composed of water. In one serving of watermelon, you will get about 5 ounces of water, which makes it a healthful food for meeting your daily water needs. Men and women need between 9 and 13 cups of water per day.

Selection and Storage

A fruit that is considered "heavy for its size," means that the fruit has a higher chance of being a fresher, juicier watermelon.

The outside should be firm and free of nicks or dents. Look for the "ground spot" where the melon was resting on the ground. In a melon that is fully ripe, this spot will be a creamy yellow color.

An uncut watermelon can be stored at room temperature, but it is better stored in a cooler place, ideally between 50 F and 60 F. After cutting, watermelon should be refrigerated.

    Low Carb Food Groups

    Most fruits, grains, legumes, and dairy products tend to be higher in sugars or carbs. You can enjoy them as part of a balanced diet, but be sure to note their carb content and limit your portions. If a low-carb diet plan is what you are looking for, then leafy vegetables and nuts and seeds seem to be the best bets.

    A Word From Verywell

    While watermelon may look like it is high in carbohydrates, you can enjoy this fruit on a low-carb diet if you pay attention to portion sizes. It adds a colorful element to a green salad or fruit salad. A bit of natural sweetness may also please your palate, and you won't be wasting your carb allowance on something will less nutritional value.


    Atkinson FS, Foster-Powell K, Brand-Miller JC. International Tables of Glycemic Index and Glycemic Load Values: 2008. Diabetes Care. 2008;31(12):2281-2283. doi:10.2337/dc08-1239.

    USDA National Nutrient Database for Standard Reference, Release 28. USDA.