Where Do Potatoes Fall in the Carb Spectrum?

How potato lovers manage a low-carb diet

Potatoes
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There is no doubt about it, potatoes are at the top of the high-carb and high glycemic vegetable list. If you are on a low-carb diet you probably miss potatoes, especially if it is your go-to comfort food. There is good news though if you are on a moderate-carb diet, small amounts of nutritious potatoes are not a bad choice, and if you are on a low-carb diet there are some tasty and healthy alternatives to potatoes.

Carbohydrate and Fiber Counts for Potatoes

Potatoes are among the highest carb vegetables, starchy, and highly glycemic. If you are on a restricted carb diet, then potatoes should be avoided.

Potato preparationCarb, fiber and calorie counts
1/2 cup diced raw potato12 grams net carbs, 2 grams fiber, 58 calories
1 medium potato (up to 3 1/2 inches in diameter; about 7.5 ounces)33 grams net carbs, 5 grams fiber, 164 calories
1 large potato (up to 4 1/2 inches in diameter; about 13 ounces)57 grams net carbs, 8 grams fiber, 284 calories
1/2 cup mashed potato made with milk (no butter):17 grams net carbs, 2 grams fiber, 87 calories
1/2 cup mashed potato made from dehydrated (instant) potatoes with milk13 grams  net carbs, 2 grams fiber, 114 calories

Glycemic Index for Potatoes

The glycemic index of a food is an indicator of how much and how fast a food raises your blood sugar. Studies of the glycemic index of potatoes are many and varied.

The results are everywhere from 56 to 111. Most of the computed averages are in the mid-to-high 80s, making potatoes one of the most glycemic foods around, although the waxy varieties, such as new red potatoes, which tend to hold their shape instead of breaking down into starch, are somewhat less glycemic than russets and other starchy potatoes.

Potatoes are even more glycemic than sugar.

Estimated Glycemic Load of Potatoes

The glycemic load of a food is related to the glycemic index but takes serving size into account. A glycemic load of one is the equivalent of eating 1 gram of glucose. 

Estimated glycemic load of pototoes
1/2 cup diced raw potato: 6
1 medium potato (2½ to 3½ inches in diameter; about 7.5 oz):  17
1 large potato (3 to 4½ inches in diameter; about 13 oz): 29
1/2 cup mashed potato made with milk (no butter): 8
1/2 cup mashed potato made from dehydrated (instant) potatoes with milk: 7

Health Benefits of Potatoes

Potatoes are a very good source of vitamin C and potassium and a good source of folate, vitamin B6, and manganese. They also contain a fairly high concentration of antioxidant phytonutrients compared to other foods by volume or weight. On a per-calorie basis, however, potatoes are not as high calorie as many of the non-starchy vegetables.

There are more than 100 varieties of potatoes, and each has its own constellation of nutrients.  The blue, purple, and red varieties of potatoes tend to have more phytonutrients.

Good Potato Substitutes

There are some root vegetable substitutes, like turnips or celery root, that are not as carb-loaded.

You might want to try low-carb recipes that offer substitute options for common potato dishes.

Sources

  • Leroux, Marcus, Foster-Powell, Kaye, Holt, Susanna and Brand-Miller, Janette. "International table of glycemic index and glycemic load values: 2002." American Journal of Clinical Nutrition. Vol. 76, No. 1, 5-56, (2002).​

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