Is Watermelon Keto-Friendly?

Dr. Eric Berg 08/31/2023

Summer is a time for fun in the sun, outdoor barbeques, and refreshing watermelon—but is watermelon keto-friendly?

Even if you’ve been following the keto diet for a while, it can be difficult to remember which foods to include in a Healthy Keto™ diet. So, think of this as your refresher on summer refreshments.

Watermelon on the table

What is the ketogenic diet?

The ketogenic diet is popular for weight loss and includes food choices high in healthy fats, moderate in protein, and low in carbohydrates.

The goal of the ketogenic diet is to use healthy fats as the body’s energy source. By depleting the body’s sugar reserves, the diet puts the body in a state of ketosis.

Ketones are produced by the liver when your body burns stored dietary fat for energy instead of carbs. Ketones are an efficient fuel for the body.

Foods high in carbs—including pasta, white flour, table sugar, grains, and processed foods and drinks—are off-limits on keto. These are replaced with high-fat, low-carb foods, including:

Meat (chicken, beef, and pork)
Fatty fish (salmon, shrimp, mackerel, tuna, and oysters)
Avocados
Healthy oil (coconut oil, MCT oil, avocado oil, and olive oil)
Butter
High fiber, low-carb vegetables (green leafy vegetables, zucchini, lettuce, and cucumbers)

Most fruit is either limited or eliminated on a low-carb diet, depending on the type.

Watermelon nutrition facts

Watermelon is not only great tasting, but it’s also rich in nutrients, including:

26 mg vitamin A
12 mg vitamin C
170 mg potassium
0.1 mg vitamin B6

These essential vitamins and minerals provide some pretty amazing health benefits.

Vitamin A - Supports healthy skin and eyes.

Vitamin B6 - Promotes a healthy immune system, supports healthy nerve function, and helps you break down and absorb protein.

Vitamin C - Helps the body absorb iron and boosts immune function.

Potassium - Supports normal heart and nerve function.

Watermelon hydrates the body and is high in an antioxidant called lycopene, which gives it its rich red color. Watermelon is also linked to a decreased risk of heart disease, cancer, and age-related eye diseases (such as macular degeneration).

Keto watermelon salad

What is the glycemic index?

The glycemic index (GI) is a way to calculate the effect of a food’s sugar content on the body. The GI is expressed in a number assigned to each food item (such as potatoes, apples, oatmeal, and carrots). This number designates how fast a particular food causes sugar to be absorbed into the bloodstream and the speed at which the blood sugar increases in response to food.

A glycemic index of 55 or less is low, 56 to 69 is moderate, and over 70 is high.

The glycemic load (GL) affects the glycemic index; the GL helps estimate how various portions of different food items compare with others in how they impact rising blood sugar levels.

Any food item ranking under 10 GL is considered low; a GL rating of 10 to 20 is moderate, and over 20 is high.

On the keto diet, you want to select foods with low GI and GL levels, but many people find using GL provides a better value of how what we eat affects our blood sugar levels.

Watermelon is high on the glycemic index, at 72—but it has a low glycemic load at only 5 per 120-gram serving.

How much watermelon can you have on a keto diet?

If you have a sweet tooth, you’ll be happy to learn that you can have watermelon on a keto diet. But to stay within the allowance of your daily total net carbohydrates, you need to limit the amount you eat. Compared to other melons watermelon is the best choice.

On the keto diet, your total carb intake should be between 20 and 50 net carbs per day. Net carbs are the total grams of carbs minus the grams of fiber.

One cup of watermelon has 11 grams of net carbs. You also need to keep in mind that the more watermelon you eat, the more the GL increases. This means that, while watermelon is keto-friendly and may even help curb those sugar cravings, you should only eat small amounts (no more than half a cup per day).

Ways to use watermelon on keto

There are plenty of ways you can enjoy watermelon on the keto diet. Of course, it’s great on its own–but there are a lot of creative recipes involving watermelon to help you mix things up.

You can turn it into a tasty keto-friendly dessert by making a watermelon smoothie with whole cream or freeze it for an icy cold treat.

For a sweet and savory option, try adding watermelon to your salad with some feta cheese, fresh mint, greens, red onions, and a homemade balsamic vinaigrette dressing. You can even grill watermelon or pickle the rind.

Dragon fruit cut in half

Best and worst fruits on keto

Keto-friendly fruits

If you want to switch things up or include another type of fruit with your watermelon, berries are a great option. Berries are low-carb fruits and are low enough in sugar to be part of the ketogenic diet.

To take it one step further, wild-sourced fruit (like wild blueberries) are lower in sugar and have a lower carb count than farm-raised berries. Unsweetened acai berries and dragon fruit are also excellent keto choices.

Non-keto fruits

Most types of fruit have too much sugar to be considered keto because they are too high in fructose (fruit sugar), raising your daily carbs. For example, an apple has 19 grams of sugar.

Pineapples, oranges, and most other fruits are also very sweet. Though many of these are high in dietary fiber, they still have high GI or GL levels.

The worst offenders are bananas (20 carbs per 3.5 ounces) and grapes (16 carbs per 3.5 ounces).

Fruit juice is even worse than eating the whole fruit when it comes to fructose content. Commercially packaged juice is pasteurized by using high heat that kills most of its nutrients and enzymes. This leaves you with concentrated fructose. Many store-bought juice brands even have added corn syrup.

High fructose levels and corn syrup cause your blood sugar to spike and may lead to insulin resistance and fatty liver disease. Dried fruits are also a snack you should avoid when on the keto diet. Contrary to popular belief dried fruits are not a healthy snack because of the concentrated sugars.

You should always consume the watermelon flesh as a whole—not just the juice. Watermelon juice has a high glycemic load without the fiber to buffer it.

Sliced watermelon on sticks

Key takeaways

Many people go on the keto diet for weight loss. But to achieve the best results, you can’t focus only on losing weight—you also have to focus on building your health. This means finding healthy keto foods you enjoy so you don’t deviate from the plan.

Watermelon is a healthy, delicious, and low-carb fruit—making it a fantastic keto-friendly choice.

The glycemic index and glycemic load are tools to calculate how fast sugar is absorbed into your bloodstream from a particular food item. Watermelon is high on the glycemic index but has a low glycemic load.

Most fruits are high in fructose and are not recommended on the ketogenic diet. But watermelon contains many nutrients, hydrates the body, and can stay within your daily carb intake limit.

FAQ

1. How many carbs are in watermelon?

One cup of watermelon contains 11 grams of net carbs and 46 calories.

2. Can I eat watermelon on a low-carb diet?

Yes, you can eat watermelon on a low-carb diet, provided you limit the amount you eat. On the keto diet, you should not eat more than a half cup per day.

3. Will watermelon kick me out of ketosis?

Yes, eating too much watermelon (more than half a cup per day) will kick you out of ketosis and reduce the health benefits of keto.

4. How much watermelon can I have on keto?

You should consume no more than half a cup of watermelon per day.

5. Is watermelon healthy on a keto diet?

Yes, watermelon hydrates and provides many important nutrients, including vitamin C, electrolytes, and antioxidants.

6. Will watermelon break a fast?

Yes, you should only consume watermelon during a meal and not when you are fasting.

7. What fruit can I eat on a keto diet?

You can eat watermelon and low-carb berries, such as raspberries, strawberries, blueberries, and blackberries on the keto diet.

8. How many carbs are in a whole watermelon?

There are about 341 grams of carbs in a 15-inch long, 7.5-inch diameter watermelon.

9. What melon is keto-friendly?

In addition to watermelon, honeydew melon and cantaloupe are considered keto-friendly, but like watermelon, you should limit the amount you eat daily.