Unlike the glycemic index of potatoes, a sweet potato's glycemic index (GI) changes with how it's cooked!
The 2021 international glycemic index tables show that sweet potatoes can be high glycemic or low glycemic depending on the preparation method.
Multiple factors determine how a food affects blood sugar:
- the region where it's grown.
- how long it's grown.
- how ripe it is.
- how it's prepared.
- how long it's cooked.
- and more!
A sweet potato is a great example of how these factors influence glycemia.
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Sweet Potato Glycemic Index & Glycemic Load
Sweet potatoes are low glycemic when boiled, and high glycemic when cooked any other way. Boiled sweet potatoes are roughly 46 on the glycemic index scale (low), and roughly 81 when cooked differently (high).
Glycemic load varies by serving size. As a single carbohydrate choice, which is a portion equivalent to 15 carbs, the glycemic load for boiled sweet potatoes is 7 (low), and 12 for other preparations (medium).
Compare sweet potato GI to white potato GI side-by-side.
The Data
The international glycemic tables report 13 varieties of sweet potatoes using 5 cooking methods. They show that all varieties had similar values in the same cooking method. Boiling, however, stood out as an exceptional method.
Here is a summary of the results.
| Cooking Method | Average Glycemic Index | Classification |
|---|---|---|
| Baked | 88 | High |
| Roasted on charcoal | 86 | High |
| Not specified* | 81 | High |
| Fried wedges | 71 | High |
| Boiled, peeled & sliced | 46 | Low |
- Note 1:
The same varieties were tested for baking and boiling, including orange, purple, and yellow fleshes; all from Jamaica. In each instance, the glycemic index when boiled was almost half of what is was when baked! - Note 2:
Two varieties from Australia were included in the boiled category and they were the only varieties to test in the medium and high glycemic ranges. All Jamaican varieties tested as low glycemic.
This chart shows that baking, roasting, frying, or otherwise cooking a sweet potato makes it high glycemic, but boiling it lowers the GI significantly.
Sweet Potato Nutrition
The following nutritional data is based on approximately ⅓ cup serving; pulled from the USDA FoodData Central database.
| 100g boiled | 100g baked | |
|---|---|---|
| Calories (kcal) | 76 | 90 |
| Fat (g) | 0 | 0 |
| Carbs (g) | 18 | 21 |
| Fiber (g) | 3 | 3 |
| Protein (g) | 1 | 2 |
Sweet potatoes are an excellent source of vitamins A, C, and B6, as well as potassium, copper, and manganese.
FAQs
Concerning glycemic response, sweet potatoes can spike blood sugar similar to potatoes, but boiled sweet potatoes are low glycemic at 46 on the index scale and have a much lesser effect.
Sweet potatoes are low glycemic only when boiled. Other preparation methods significantly increase a sweet potato's glycemic index according to the data in the international glycemic index tables.
Sweet potatoes are mostly carbohydrates and can spike blood sugar if 1) not portioned and/or 2) not paired with protein.
Summary
Sweet potatoes, though starchy, are nutrient-dense and can be part of a low-glycemic meal plan. Portioning will always be key to preventing blood sugar spikes. When baked, sweet potatoes are high glycemic, no matter the variety. But when they're boiled, their glycemic effect is cut in half, making them low glycemic!
Recipes with Sweet Potato
More Glycemic Index Info
- Carrots glycemic index
- Glycemic index of fruits
- Can diabetics eat potatoes?
- Can diabetics eat watermelon?
- Diabetes mango info
More to See
Share with us how you eat sweet potatoes in the comments below.
Miryam Koch
Thank you so much for your website / postings. I wish you only the best in your endeavor to complete your Masters in Nutrition & Dietetics. Please let me know when you've graduated!
I found lots of valuable information here in my search for "scientifically accurate GI Chart". Since being diagnosed as a Type 2 diabetic in December 2022 I have been experimenting with a mostly animal / oil free diet and have until the end of March to adjust my numbers with different eating habits when I go in for another blood test.
Traci Houston
Thank you so much for the helpful feedback and well wishes! I will certainly keep in touch 🙂
Wow, those are two major steps! I hope they pay off!
Have you heard of Mastering Diabetes? They take a similar approach to "reversing" diabetes. This podcast episode worth listening to. https://www.podbean.com/ep/pb-624xb-1328237 or you can watch it on YouTube https://www.youtube.com/watch?v=8ccbARRV2yg&list=PLwVXgmubuwgIFmR8B4iw8P4gTWqZ4gHgP&index=8