Does watermelon raise blood sugar?
Watermelon has a high glycemic index (72) but a low glycemic load (5 per typical serving), because it's mostly water. This confuses people: the GI number looks alarming, but the practical glucose impact of a normal portion is usually modest.
GI vs glycemic load
Glycemic index measures how quickly a food raises blood sugar per 50g of carbohydrate. To get 50g of carbs from watermelon, you'd need to eat about 700g, roughly half a small watermelon. Nobody does that in one sitting. A typical portion (150-200g) contains about 10-15g of carbs, which is the glycemic load figure, and it's low.
In practice, a reasonable serving of watermelon produces a gentle glucose rise of 1-2 mmol/L in most people, similar to an apple. The high GI number reflects how fast the sugar absorbs, not how much there is in a real portion.
When watermelon does spike you
Large portions do add up. A big bowl at a barbecue (300g+) delivers enough sugar to produce a noticeable spike. Eating watermelon on an empty stomach, without any protein or fat to slow absorption, produces a faster and higher response than eating it as part of a meal.
Watermelon juice and smoothies concentrate the sugar and remove the fibre, producing a sharper spike than whole fruit. If you're blending watermelon, adding some protein (yoghurt, protein powder) flattens the response.
The individual factor
Some people spike from watermelon more than the averages suggest. Insulin sensitivity, gut bacteria composition, and what you've eaten earlier in the day all affect the response. The pairing trick works here too: watermelon after a meal with protein and fat produces a much flatter glucose curve than watermelon alone as a snack.
A CGM shows you exactly what watermelon does to your blood sugar. Nico's coaching helps you decide whether to change the portion, the timing, or the pairing, based on your data rather than a generic GI table.
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