Is Watermelon Keto-Friendly?

Imge of Is Watermelon Keto-Friendly?



In this article we will explore the globally popular watermelon. It is almost impossible to picture a hot summer’s day without you sinking your teeth in its wonderful flesh. 

But wait a minute, how about your keto diet? Will your new regimen interfere with your favorite fruit? 

This article will explore this very question, giving you the full nutritional picture of this fruit, including the information you need to make the best choice for yourself. Enjoy your read! 


What is a watermelon?

Watermelons, or Citrullus lanatus, are a part of the huge gourd family which includes gourds, melons, cucumbers, and zucchinis, among many others. The climate required for their cultivation needs to be consistently warm for extended periods of time. In the US they are grown in sunny states such as Florida, California, and Texas. About 75% of the world’s production of these gentle giants comes from Asia, with China in the lead.

There are numerous cultivars out there, and consequently these fruits will vary in shape, weight, flesh color, and rind pattern. There are even seedless varieties! 

We will concentrate in this article on your average supermarket variety with its crimson red flesh and jet black seeds. 


Watermelon nutrition facts

Serving size: 100 g

  • Calories: 30 kcal
  • Fat: 0.2 g
  • Net carbs (total carbs - fiber): 7.2 g
  • Total carbs: 7.6 g
  • Fiber: 0.4 g
  • Protein: 0.6

As you can see, these fruits are very low in calories with less than 1 g of fat and protein. In fact, they are over 90% water and are most hydrating, another reason why they are so favored on a hot summer’s day. 

In terms of net carbs, 7.2 g is moderate in relation to other fruits. The carbs in watermelon are virtually all free sugars, primarily fructose but with moderate amounts of glucose and sucrose too.

In terms of how this food can add to your recommended daily amount (RDA) of vitamins and minerals, please see the table below.


 Men / Women

(age 19-70) RDA 

 In 100 g of Watermelon   As a % of RDA for Men / Women 
 Vitamin C 90 / 75 mg per day 8.1 mg 9% / 10.8%
 Vitamin A 900 / 700 mcg per day 28 mcg 3.1% / 4%


The table shows you that watermelon contains moderate amounts of Vitamin C and small amounts of Vitamin A. It actually contains only provitamin A, but it gets converted in our bodies in the active form.

Watermelons are also very rich in a phytochemical called lycopene, with 4,530 mcg per 100 g serving. Lycopene is the pigment that gives the reddish color to these fruits and other produce such as tomatoes. Lycopene has been shown in studies to protect against cardiovascular disease and certain cancers, specifically prostate cancer.


Can you eat watermelon on a keto diet?

This is a tricky question; it really depends on your personal daily net carb limit. If you are on a tight limit of 10-15 g of net carbs, then perhaps give these a skip. As they are a fruit, they would only normally be eaten as a snack or part of dessert. So it would make more sense to leave your allowance for the main meal.

If however, you are more flexible and consume 25-50 g per day, then it is perfectly acceptable to incorporate it into your diet regimen as a snack or dessert once or twice a week.


How much watermelon can you eat on the keto diet?

Let’s answer this question assuming your personal allowance is 25-50 g of net carbs per day. The net carb content of a 100 g serving is significant, so it would be recommended to not exceed this serving size in order to stay within your daily carb allowance.

This is especially true if you have already eaten some carbs or are planning to eat some carbs later that day.

The reason for stressing the need to be prudent here is that a typical wedge weighs around 286 g, turning out a costly 20.5 g of net carbs. 

On a hot day, you could lose yourself in a succulent wedge and in literally a matter of seconds, you could eat a whole wedge! 

It would be most wise to invest in a digital kitchen scale to ascertain the weights of the foods you are eating.


What kind of watermelons can you have on keto?

There are many different cultivars out there, and hence in different parts of the world a variety of cultivars may be available to you. However, they all share similar properties in terms of high water content, significant carbohydrate fractions, and negligible amounts of fat and protein. 

So in essence the advice remains the same; if on a very strict carb limit, leave this fruit out of your diet to leave space for carbs in meals. 




What can you eat them with?

It can be argued that the most popular way to eat them is simply on their own, preferably together with some hot, golden sunshine above! However there are other ways to consume this delightful fruit.

  • Chop up into small cubes and toss into a fresh salad; this adds crunch and mild sweetness.
  • Cut into squares and top them with some feta cheese and herbs.
  • Cut into fingers, pop a popsicle stick on one end, and freeze in popsicle molds for a healthy choice on a hot day! 

Keto-friendly alternatives

We mentioned how watermelons are a part of the gourd family; let’s explore some keto-friendly alternatives that are also in this family.

  • Pumpkin - loaded with Vitamin A and potassium, these colorful and seasonal veggies contain only 6 g of net carbs per 100 g serving. Definitely an acceptable and healthy alternative.  
  • Zucchini - here again we find a veggie loaded in potassium and Vitamin C and costing just 2.01 g of net carbs per 100 g serving. So a big yes.
  • Cucumber - with over 95 percent water you would be surprised if there was any nutrition here. In fact, these long green fellas contain moderate amounts of potassium, small amounts of Vitamin A and calcium and an impressive amount of Vitamin K. Moreover the net carb cost per 100 g is only 3.13 g.    


FAQs about watermelon on a keto diet

Click to see answers to some of the most frequently asked questions about including this food on a ketogenic plan.

As with many fruit juices, there are simply too many net carbs in a 150 ml serving to justify its consumption. Better to stick to the actual fruit. In the case of watermelon juice, such a serving will come at a cost of 11.33 g of net carbs.

Indeed you may! These have been shown to be rich in fat, protein and fiber. They also contain appreciable amounts of minerals such as potassium, magnesium, iron, and zinc. They are a good source of B vitamins as well as possessing powerful antioxidant activity. 

While it has been elusive to find a net carb figure for fresh seeds, the implication of the studies researched here definitely lean towards the consumption of such seeds for a keto diet.    

Yes! The rinds are actually edible. Watermelons are known to contain the amino acid citrulline; apparently this amino acid is concentrated in the rind. There is some anecdotal evidence that this amino acid may help with erectile dysfunction. The rinds are also rich in fiber.

It’s okay to call it either; botanically speaking it is a seed containing fruit,  but it is also related to the gourd family of vegetables. So call it what you want, it's totally acceptable.

Eating the fruit by itself may not work; as you are probably hungry you are more likely to eat more than you should. Additionally, it may not fill you up; remember it’s 92% water! Instead try topping watermelon squares with some feta cheese or cottage cheese. This will add fat and protein to your meal and will keep you satiated. 

Or, finely chop some watermelon over some natural yogurt or creme fraiche to add crunch and sweetness.

Have you ever heard of FODMAPS? It’s basically a classification for foods based on the type of sugars present in them. Watermelon is a high FODMAP food and may cause sensitivity in those with Irritable Bowel Syndrome as well as in any individuals if eaten in excess. 


Other types of fruit to consider on keto