Watermelon's Impact On Ketosis: Friend Or Foe?

The keto diet is a high-fat, low-carb diet that was originally designed for epilepsy patients but has become popular for weight loss. The diet is restrictive and requires strict adherence to maximise results, with many fruits considered off-limits. However, watermelon is relatively low in carbohydrates compared to other fruits, and can be enjoyed as part of a keto diet in moderation. A cup of diced watermelon contains about 11.5 grams of carbs and 0.5 grams of fibre, which means it has about 11 grams of net carbs. Net carbs are the number of carbs in a portion of food that is absorbed by the body. Whether watermelon can fit into a ketogenic diet depends on what else you're eating during the day. For example, on a 2,000-calorie diet, you may restrict your carb intake to 25 grams per day, so a single serving of watermelon could take up nearly half of your daily carb allotment. Therefore, while watermelon can be keto-friendly, it may require careful planning and decreased portion sizes to stick within your daily carb allotment.

How much watermelon can you eat on keto?

Watermelon is a refreshing, hydrating, and nutrient-dense fruit that can be enjoyed as part of a ketogenic diet—but only in moderation. The amount of watermelon you can eat on keto depends on your daily carbohydrate target and what other foods you eat during the day.

Carbohydrate Content of Watermelon

Watermelon is relatively low in carbohydrates compared to other fruits. One cup (152 grams) of diced watermelon contains about 11.5 grams of total carbohydrates, including 0.5–0.6 grams of fiber and nine grams of sugar, which equates to around 11 grams of net carbs. Net carbs refer to the number of carbohydrates absorbed by the body and are calculated by subtracting the grams of fiber from the total grams of carbohydrates.

Daily Carbohydrate Intake on Keto

On a typical ketogenic diet, carbohydrates are restricted to 5–10% of total calories. For a person consuming 2,000 calories per day, this equates to a daily carbohydrate intake of 20–50 grams.

Whether you can stay in ketosis after consuming watermelon depends on your daily carbohydrate target and what else you eat during the day. A single serving of watermelon could take up nearly half of your daily carb allotment if you are aiming for only 20 grams of carbs per day. If you are aiming for around 50 grams of carbs per day, then one cup of diced watermelon comprises 23.2% of your daily carbs.

Therefore, careful planning and reduced portion sizes are necessary to include watermelon in a ketogenic diet. Kim Yawitz, a registered dietitian, recommends that those on a keto diet eat no more than one cup of watermelon per day.

Other Keto-Friendly Fruits

Other fruits that are considered keto-friendly and can be enjoyed in moderation include avocados, lemons, limes, strawberries, raspberries, blackberries, tomatoes, and peaches.

Is watermelon high in carbs?

Watermelon is relatively low in carbohydrates compared to other fruits. One cup (152 grams) of diced watermelon contains about 11.5 grams of carbs and 0.5 grams of fibre, which means it has about 11 grams of net carbs. Net carbs are the number of carbs in a portion of food that is absorbed by the body. They are calculated by subtracting the grams of fibre from the total grams of carbohydrates.

However, watermelon is high in natural sugars, which can affect ketosis and prevent the body from maintaining a state of ketosis. Therefore, it is important to eat watermelon in moderation while following a ketogenic diet. A person can eat watermelon and other fruits while staying in a state of ketosis, but it depends on their daily carbohydrate target and what else they eat during the day.

For example, on a 2,000-calorie diet, a person may restrict their carb intake to 25 grams per day. A cup of diced watermelon contains 11 grams of net carbs, which means it could take up nearly half of the daily carb allotment. Therefore, eating watermelon on a keto diet may require careful planning and reduced portion sizes.

Kim Yawitz, a registered dietitian, recommends that those on a keto diet eat no more than one cup of watermelon per day. Yawitz also cautions that even non-starchy vegetables have carbs, so it is important to plan your carb intake to ensure you do not exceed your limit.

Other keto-friendly fruits

Avocados are low in carbs and high in heart-healthy fats and fibre, as well as other important vitamins and minerals. Lemons and limes are also much lower in carbs than other fruits. Certain types of berries, such as strawberries, raspberries, and blackberries, can be enjoyed in moderation as they are high in fibre and lower in net carbs.

Is watermelon keto-friendly?

Watermelon can be enjoyed as part of a keto diet, but only in moderation. As a keto diet is highly restrictive, with a focus on low carbohydrate consumption, the natural sugars in fruit can take you out of ketosis.

Carb content of watermelon

A cup of diced watermelon (152 grams) contains about 11.5 grams of carbs and 0.5 grams of fibre, which means it has about 11 grams of net carbs. Net carbs are the number of carbs in a portion of food that is absorbed by the body. They are calculated by subtracting the grams of fibre from the total grams of carbohydrates.

On a 2,000-calorie diet, you may be restricting your carb intake to just 100 calories, or 25 grams, per day. Therefore, a single serving of watermelon could take up nearly half of your daily carb allotment.

How to include watermelon in a keto diet

If you are on a keto diet, you can still eat watermelon, but you may need to reduce your portion sizes and plan carefully to keep your carb count in check. Kim Yawitz, a registered dietitian, recommends that those on a keto diet eat no more than one cup of watermelon per day. Yawitz also points out that watermelon is very hydrating, which is beneficial for keto dieters as dehydration is a common side effect of the keto diet.

Other keto-friendly fruits

Avocados, lemons, limes, strawberries, raspberries, blackberries, tomatoes, and peaches are all keto-friendly fruits. These fruits are low in net carbs and high in fibre, vitamins, and minerals.

Potential risks of the keto diet

The keto diet can be quite extreme, and it is important to note that there is limited evidence of its long-term effects. It can also be difficult to get all the necessary nutrients while on a keto diet, and it may cause side effects such as difficulty exercising, constipation, and "keto flu". It is recommended that anyone considering a keto diet first seek advice from a doctor or registered dietitian.

What are the health benefits of watermelon on keto?

Watermelon is a keto-friendly fruit, provided it is consumed in moderation as part of a well-planned ketogenic diet. It is a good source of hydration and several essential nutrients, including vitamins C and A, and antioxidants such as lycopene, which may offer protection against heart disease and certain cancers.

Hydration

Watermelon is a hydrating fruit, with a high water content of around 92% by weight. This makes it an excellent choice for anyone experiencing dehydration, a common side effect of the keto diet.

Vitamins and Nutrients

A single cup of diced watermelon provides 21% of the daily requirement of vitamin C, an antioxidant that helps the body maintain healthy tissues, blood vessels, and bones. It also assists in forming collagen, healing wounds, and absorbing plant-based iron.

The same serving of watermelon also contains around 17% of the daily vitamin A requirement, which helps maintain the immune system and keeps the skin and eyes healthy.

Antioxidants

Red-fleshed watermelons are rich in lycopene, a carotenoid antioxidant also found in tomatoes and pink grapefruits. Lycopene gives these fruits their reddish colour and has been linked to improved heart health and a reduced risk of certain cancers.

Weight Loss

The high water content of watermelon means it has a low energy density compared to other fruits. This can promote a feeling of fullness, or satiety, which may aid in weight loss and weight maintenance, a common goal for those following a keto diet.

Other Benefits

Watermelon is also one of the best food sources of citrulline, an amino acid that can be converted into nitric oxide in the body. Nitric oxide can help increase blood flow to the muscles and may also have other beneficial effects.

Planning and Portion Control

While watermelon is a keto-friendly fruit, it is important to remember that it still contains carbohydrates and natural sugars. Therefore, careful planning and portion control are necessary to ensure that it fits within the desired macronutrient ratio of a ketogenic diet.

For those aiming for a very low-carb intake of around 20 grams of carbs per day, a single cup of diced watermelon could make up more than half of their daily carbohydrates. As such, it is recommended to limit watermelon consumption to no more than one cup per day.

What other fruits can you eat on keto?

The keto diet is a very low-carb, high-fat eating plan. Carb intake is often restricted to less than 20-50 grams per day. The main objective of the keto diet is to reduce your intake of carbohydrates to the absolute minimum to achieve and maintain the state of ketosis, a metabolic state that can help with losing weight and improving blood sugar levels.

While the keto diet is restrictive, there are certain fruits you can still eat. Generally, these fruits will be low-carb and low-sugar options. Some fruits, like avocados, will also include a healthy dose of fat, making them an even more keto-friendly choice.

• Avocados: Avocados are often used like a vegetable in savory dishes, but they are actually a seed-bearing fruit. They are promoted for their rich and healthy fat content and are also keto-friendly due to being low-carb. Avocados have around 8.5 grams of carbohydrates, 6.7 grams of fiber, and 14.7 grams of fat per 3.5-ounce fruit (100-gram serving). They also contain various essential nutrients, including vitamin C, vitamin K, potassium, and folate.
• Blackberries: Blackberries are another superfood berry that is low on the glycemic index. They have a comparatively low carb count, especially when compared to blueberries. One cup (144 grams) of blackberries contains 13.8 grams of carbohydrates and 7.6 grams of fiber. They are packed with the powerful disease-preventing and disease-fighting vitamin C, as well as other essential nutrients, including vitamin K and manganese.
• Lemons: Lemons are a particularly solid choice for the keto diet. One lemon contains 6 grams of carbs and 1.8 grams of fiber, or 0.7 grams of carbs per wedge. They are also an excellent source of vitamin C and are considered a low-glycemic food that will not cause spikes in blood glucose.
• Raspberries: Raspberries are another excellent berry choice for people following a keto diet. About 19 raspberries contain 2.6 grams of carbs and 1.4 grams of fiber, making this serving size a great side addition to a protein and fat-packed snack of nuts or cheese. They are considered one of the healthiest fruits and are high in antioxidants, which can help reduce inflammation and lower the risk of certain chronic diseases.
• Tomatoes: Tomatoes are another low-carb fruit suitable for people following a keto diet. One cup (180 grams) of raw tomatoes contains about 7 grams of carbs and 2 grams of fiber. They are also low in calories and high in beneficial plant compounds, including lycopene, beta carotene, and naringenin.
• Strawberries: Strawberries are considered a low-carb and keto-friendly fruit, with around 11.7 carbs and 3 grams of fiber per 1-cup of halved berries (152-gram) serving. They also contain antioxidants, including vitamin C and lycopene, as well as other vitamins and minerals such as manganese, calcium, and folate.
• Cantaloupe: Like watermelon, cantaloupe melon provides essential nutrients in a low-carb serving. One cup of diced melon has only 12.7 grams of carbs and 1.4 grams of fiber. It is also one of the best sources of the antioxidant beta-carotene, which is associated with eye health. Cantaloupe also provides other essential nutrients, including vitamin K, potassium, and folate.

Frequently asked questions