Watermelon Glycemic Index, Glycemic Load, and Blood Sugar Response Chart
Based on
Blood Glucose Response Chart
Watermelon has a high Glycemic Index (GI) of 72 and a low Glycemic Load (GL) of 5 per 100g, meaning it causes a quick but mild rise in blood sugar when eaten in moderation.
Watermelon (Citrullus lanatus) is a widely cultivated fruit that comes from a vine-like flowering plant in the gourd family (Cucurbitaceae). Known for its trailing growth habit, watermelon is grown in warm climates around the world and is available in over 1,000 different varieties. Both the plant and its edible fruit share the same name.
While it's often seen as a healthy snack, watermelon's glycemic effects has sparked debate, especially among people managing blood sugar levels, diabetes, or low-GI diets.
Glycemic Index is a ranking system that measures how fast a food causes blood glucose levels to rise after eating. Foods with a high GI, like watermelon, are digested rapidly and can lead to spikes in blood sugar. However, Glycemic Load adjusts for portion size, offering a more complete picture of a food’s impact.
In this guide, we explore watermelon's overall impact on blood sugar, helping you decide whether it deserves a place in your diet. Along the way, we’ll break down how watermelon portion sizes matter, and how to pair it with other foods effectively to manage blood sugar.
Watermelon Nutrition Facts
How Many Carbs Are In Watermelon?
Watermelon contains 7.6g of Total Carbohydrates and 7.2g of Net Carbohydrates per 100g serving. A typical serving of 1 cup diced (152g) contains 11.5g total carbs and 10.89g net carbs.
Total Carbohydrates and Net Carbohydrates in Watermelon by Serving Size:
| Serving Size | Total Carbs (g) | Net Carbs (g) |
|---|---|---|
| 1 Oz (28.35g) | 2.1g | 1.99g |
| 100 Grams (100g) | 7.6g | 7.2g |
| 1 Slice (120g) | 9.06g | 8.6g |
| 1 Cup diced (152g) | 11.5g | 10.89g |
| 1 Wedge (286g) | 21.59g | 20.49g |
How Much Sugar Is in Watermelon?
Watermelon contains 6.2g of sugar per 100g, contributing to its high GI. For example, a 1-cup diced serving (152g) has 9.4g of sugar.
How Much Fiber Is in Watermelon?
Watermelon contains 0.4g of fiber per 100g. A typical serving of 1 cup diced (152g) contains approximately 0.61g of fiber. This low fiber content contributes to its high Glycemic Index, as there’s minimal dietary fiber to slow down the digestion and absorption of its natural sugars, leading to a quicker spike in blood glucose levels.
Why Watermelon Has a High Glycemic Index?
Watermelon's high Glycemic Index (GI) of 72 is largely due to its high natural sugar content, simple carbohydrates, low fiber, and high water content.
- High Natural Sugar Content: 6.2g of sugar per 100g, primarily glucose and fructose, which are rapidly absorbed and can spike blood sugar quickly.
- Simple Carbohydrates: With 7.6g of total carbs per 100g, the majority are simple sugars with minimal complex carbs or resistant starch, leading to a faster glycemic response.
- Low Fiber: At just 0.4g of fiber per 100g, watermelon lacks the dietary fiber needed to slow carbohydrate digestion and absorption, which would otherwise help stabilize blood sugar.
- High Water Content: Watermelon is about 90% water, which makes it light in calories but also means the sugars are less diluted by fiber or fat, allowing for quick gastric emptying and a rapid rise in blood glucose.
Watermelon’s Glycemic Load Remains Low
Watermelon has a low Glycemic Load across typical portion sizes. Despite its high GI, small to moderate portions have a minimal impact on blood sugar.
Watermelon Glycemic Load Per Serving Sizes:
| Serving Size | Net Carbs (g) | Glycemic Load | GL Impact |
|---|---|---|---|
| 1 Oz (28.35g) | 1.99g | 1 | Low |
| 100 Grams (100g) | 7.2g | 5 | Low |
| 1 Slice (120g) | 8.6g | 6 | Low |
| 1 Cup diced (152g) | 10.89g | 8 | Low |
| 1 Wedge (286g) | 20.49g | 15 | Moderate |
Can Watermelon Spike Blood Sugar?
Yes, watermelon can cause a spike in blood sugar due to its high Glycemic Index (GI) and rapidly absorbed natural sugars. However, because it is low in total carbohydrates, the spike is usually mild and short-lived, making it safe for most people with diabetes when eaten in controlled portions alongside protein or fiber-rich foods.
People with diabetes or those on low-carb diets should be mindful of serving size and overall meal composition to minimize any sharp glucose response.
Watermelon Impact on Diabetic, Keto, and Weight Loss Diets
Watermelon can fit into diabetic and weight loss diets in small, controlled portions due to its low calorie and low glycemic load, but it is generally unsuitable for strict keto diets because of its high sugar content and lack of fats or fiber to slow absorption.
Can People with Diabetes Eat Watermelon?
Watermelon can be safe for diabetics in moderation because of its low Glycemic Load per typical serving, despite having a high Glycemic Index (GI 72) and rapidly absorbed natural sugars.
People with diabetes often experience impaired insulin response and glucose regulation, making them more sensitive to high-GI foods like watermelon. However, watermelon's low total carbohydrate content (7.6g per 100g) means that small portions can be enjoyed without significantly disrupting blood sugar control when paired with fiber or protein.
Watermelon and Keto Diet
Watermelon is not suitable for keto diets because it is relatively high in natural sugars (6.2g per 100g) and net carbs (7.2g per 100g), with very little fat or fiber to slow down absorption or support ketosis.
The ketogenic diet relies on ultra-low carbohydrate intake and high fat consumption to trigger and sustain nutritional ketosis, a metabolic state where the body burns fat for fuel; watermelon’s high glycemic sugars and low fat content disrupt this process and offer no metabolic leverage for staying in ketosis.
Watermelon and Weight Loss Diets
Watermelon is good for weight loss due to its low calorie density (30 kcal per 100g), high water content, and naturally sweet flavor that can curb cravings for processed desserts.
Its ability to satisfy sweet cravings with minimal calories and carbs, combined with its hydrating, fiber-light profile, makes it a unique low-energy food that supports portion control and calorie reduction, which are key for sustainable weight loss.
How to Eat Watermelon Without Spiking Blood Sugar
Pair watermelon with protein, healthy fats, or fiber-rich foods to reduce blood sugar spikes.
Nuts and seeds add healthy fats and fiber, helping blunt the glycemic response. Greek yogurt offers protein and fat to slow digestion while keeping the snack refreshing and satisfying.
Cottage cheese is high in protein and it balances watermelon’s sugars and increases satiety. Boiled eggs also provide protein and fat with zero carbs, making them ideal for blood sugar stability.
Avocado’s fiber and monounsaturated fats make it a strong blood sugar-buffering partner.
Preparation Tips:
Watermelon is typically eaten raw, and its glycemic impact remains high regardless of whether it's cubed, blended, or chilled. However, blending into a smoothie with added protein (like unsweetened protein powder or nut butter) can lower the glycemic effect by slowing absorption. Avoid juicing, as it removes fiber and concentrates sugars, increasing the glycemic load.
Should You Eat Watermelon for Blood Sugar Control?
Watermelon can be part of a balanced diet for people managing blood sugar, if eaten in moderation, paired wisely, and portioned carefully.
Despite its high Glycemic Index (GI 72), watermelon’s low Glycemic Load, low calorie density, and small carb content per typical serving make it a safe choice for most people with diabetes and those pursuing weight loss. However, it is unsuitable for ketogenic diets due to its natural sugars and net carb content.
To reduce blood sugar spikes, pair watermelon with protein, healthy fats, or fiber-rich foods like Greek yogurt, nuts, or cottage cheese. Avoid juicing, and opt for whole pieces or balanced smoothies to preserve its nutritional value while minimizing glycemic impact.
Ultimately, watermelon doesn’t need to be avoided, just respected.
Portion control, pairing, and context are key.