Watermelon is delicious, healthy and refreshing food.

Watermelon is filled with vitamin C, A, and lots of healthy nutrients. It contains high water content. So, it is a very delicious way to keep your body hydrated especially in summer. [1]

It has lots of health benefits. It can decrease the risk of heart diseases, decrease inflammation and oxidative stress, and it is also beneficial for hair and skin health.   [2] [3] [4] [5]

Now the question arises, should you eat watermelon on the keto diet? Then read this article till the end you will all the pros and cons of watermelon on a ketogenic diet.

Fast facts of watermelon

  • Watermelon is widely cultivated fruit. It is grown by 96 countries around the globe.
  • There is more than 1200 variety of watermelons.
  • Watermelon is one of the oldest fruits, evidence found that watermelon history is  5000 years old.
  • Watermelon juice can help to relieve muscle tension.

How many carbs in watermelon?

1 cup (154) of watermelon contains 11g total carbs and 9g sugar or 100 g watermelon contains 7g carbs and 6g sugar, this according to USDA Food Composition Databases.

92% of its weight is due to water content. It is also low in calories. It is high in vitamins A and C. it is also a great source of magnesium and potassium

Watermelon content per 100g, according to USDA Food Composition Databases

  • Carbs 7.55g
  • Sugar 6.2g
  • Water  92g
  • Calories 30
  • Protein  0.5
  • Fiber  0.4g

Vitamin and minerals

  • Calcium 7mg (1% of DV)
  • Magnesium 10mg (2% of DV)
  • Potassium  112mg (3% of DV)
  • Vitamin C 8.1mg  (13 of DV)
  • Vitamin A   569IU (11% of DV)

Watermelon also contains other vitamins and minerals such as thiamine, vitamin B6, riboflavin, niacin, folate, pantothenic acid, magnesium, zinc copper, selenium, lycopene, betaine, and choline. Watermelon contains lycopene more than any other fruit.

Watermelon and keto diet

watermelon and keto diet.

Keto diet is a low carb, adequate-protein, and high-fat diet.

It helps you to stay in ketosis. Ketosis is a metabolic state in which the body burns fat instead of carbs for energy.

Keto diet is carbs restricted diet. Generally, you can eat a maximum of 50g carbs, more carbs can kick you out from ketosis.

Generally, fruits are restricted in keto diet because they are higher in carbs and fructose.

It is a low-carb food. 100g watermelon contains 7g carbs. But this is just one side.

  • Glycemic index (the speed at which it elevates the sugar level in blood) = 72
  • Glycemic load (the quantity of carb present in food) = 4

The glycemic index of watermelon is high. It gives a sudden spike of sugar in your blood, which is bad for ketosis. It can kick you out of ketosis.

But the good thing is that the glycemic load of watermelon is low. It contains low amount of carbohydrates. 

You can eat watermelon in ketosis as long as you are below the net carbs limit.

But you can easily overeat watermelon. So try to avoid as long as you can if you want to eat. You should eat at a very low amount. 

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When to avoid watermelon on keto?

If you are still trying to get into ketosis then you should completely avoid watermelon.

watermelon can slow down your speed to get into ketosis and you want to keto into ketosis as fast as you can right. 

Slower you get into ketosis longer the keto flu symptoms stay. It is low in carb, but at the same time, its GI is also high. Small blood glucose spikes can slow down the ketosis process, even shut off the ketosis process completely.

Before eating watermelon in a ketogenic diet, make sure you are in ketosis fully. For this, you can test the ketone level in your body. You can check ketone in blood, urine and breath. But a blood test is considered more accurate.

  1. Partial ketosis – 0.5 mmo/L. This means you are not in full ketosis yet. It is not the right time to add carbs to your diet.
  2. Optimal ketosis – 1.5 – 3.0 mmo/l. This means you are in optimum ketosis. You can test your carbs’ tolerance limit and try to add some carbs to your diet. This ketone zone is optimal for weight loss.

Only eat watermelon if you are in optimum ketosis or your blood ketone level more than 1.5 mmo/l. Otherwise, restrict watermelon completely.

One more thing if your metabolism is slow and your lifestyle is sedentary, avoid watermelon. It can mess with your ketosis.

So why take the risk just avoid watermelon during the adaptation stage and slow metabolism.

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When to eat watermelon on a keto diet?

If you are already in ketosis and all the keto-flu symptoms have gone away. 

Before eating watermelon check your blood ketone level. If you are in optimum ketosis, it is a green signal to go but don’t go too fast you can easily cross the limit.

Before eating you should be able to manage the total carbs within the limit of the ketogenic diet. 

But remember you should eat watermelon in a very low amount. If you overeat, it will be a matter of time and you will be out of ketosis. 

Bonus tip

If you want to enjoy these delicious low carbs fruits and vegtables then increase your daily activity, be more active during the day. If you are living a sedentary lifestyle. You have to stay below 20g limit and have to avoid watermelon and many other delicious foods.

How much watermelon on a keto diet?

You are following a ketogenic diet to stay into ketosis and you know watermelon can easily mess with your ketosis. You can easily overeat watermelon. So it is better to cut watermelon in pieces before eating.

1 cup(154g) watermelon contains 9g net carbs. 

There are more than 1200 varieties of watermelon and the smallest watermelon can weigh 1 pound. An average watermelon weighs around 10-12 pounds. 

You can eat an average watermelon for almost one month.

You should eat less than 1 cup on a standard keto diet and should avoid completely during the adaptions stage. But if you are very active during the day, means you do exercise or athlete, then you can eat more than 1 cups. 

Test your carb tolerance level. If your metabolism is good then you can also eat upto 1 cup of watermelon a day.

But if you are less active or your metabolism is slow, try to avoid watermelon completely.

Health benefits of watermelon on a keto diet.

  • Keto diet is a dehydrated diet. So it is very important to keep your body well hydrated especially on a keto diet. Watermelon contain 92% of water. So, it is a very delicious way to keep your body hydrated. 
  • Watermelon contains lycopene that may help you to prevent cancer.
  • It contains antioxidants that can improve heart disease and prevent oxidative damage.
  • Watermelon is also good for eye health. It can prevent age-related macular degeneration (AMD).
  • It is also good for skin and hair health.


Watermelon is low in carbs but its glycemic index is high. It contains easily digestible carbs. You can easily cross the limits of the total carbs limit.

Our words for you is that you should try to avoid watermelon completely during a keto diet. 

But if you decided to eat watermelon you should remember, you should not be in a keto adaption stage and try to keep a limit minimum but not more than 100g.


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