Potatoes, corn, peas, and cassava top the list of highest-carb vegetables, with some packing 30 to 40 grams of carbohydrates in a single serving. That’s roughly the same as a slice or two of bread. If you’re watching your carb intake, knowing which vegetables carry the most starch helps you plan meals without guessing.
Starchy Vegetables With the Most Carbs
The vegetables highest in carbohydrates are almost all starchy varieties, meaning they store energy as starch rather than having high water content like leafy greens. Here are the biggest ones to know about:
Cassava (yuca): The clear winner. A 3.5-ounce serving of cooked cassava contains about 40 grams of carbohydrates and only 2 grams of fiber. That’s nearly double what you’d get from the same amount of potato. Cassava is a staple crop across Latin America, Africa, and Southeast Asia, and it shows up in flour, chips, and tapioca.
Potatoes: A medium russet potato has about 30 grams of carbohydrates. Per 100 grams, both white and sweet potatoes come in at roughly 21 grams of carbs. Sweet potatoes edge ahead slightly on fiber (3.3 grams versus 2.1 grams per 100 grams), which slows digestion a bit, but the total carb count is essentially the same.
Corn: One large ear of corn (8 to 9 inches) counts as a full cup-equivalent serving and delivers around 30 grams of carbohydrates. Half a cup of corn kernels provides about 15 grams.
Green peas and parsnips: Both contain roughly 15 grams of carbohydrates per half-cup cooked serving. The CDC groups them alongside corn as “starchy vegetables,” each representing one full carbohydrate choice for people counting carbs.
Winter Squash: Higher Than You’d Expect
Winter squash varieties often surprise people. They taste sweet for a reason: they’re significantly higher in carbs than summer squash like zucchini.
Half a cup of baked acorn squash contains about 30 grams of carbohydrates, putting it in the same range as a medium potato. Butternut squash is a bit lower at 21.5 grams per half cup, with around 6.5 grams coming from natural sugars. Both are nutrient-dense and rich in vitamins, but if you’re on a strict low-carb plan, a serving of winter squash can use up a significant portion of your daily budget.
How These Vegetables Affect Blood Sugar
Total carbs don’t tell the whole story. How quickly a vegetable raises your blood sugar matters too, and that varies widely even among high-carb options.
Baked russet potatoes have one of the highest glycemic index values of any food, scoring 111 on the scale (where pure glucose is 100). That means they spike blood sugar fast and significantly. A boiled white potato scores lower at 82, which is still considered high. Cooking method matters: baking breaks down potato starch more than boiling does, making the carbohydrates easier to absorb.
Parsnips, despite being starchy, score a moderate 52 on the glycemic index and have a glycemic load of just 5 per half-cup serving. That’s because the serving is smaller and the fiber content helps buffer absorption. Boiled carrots come in even lower at 33, with a glycemic load of only 1 per half cup, meaning they barely register in terms of blood sugar impact despite technically being a “carby” root vegetable.
The practical takeaway: a boiled potato and a serving of parsnips might both be starchy vegetables, but one will affect your blood sugar six times more than the other.
Putting Carb Counts in Context
Serving size makes a huge difference. Half a cup of corn is 15 grams of carbs, which is manageable for most people. But sit down with two ears of corn at a barbecue and you’ve eaten 60 grams of carbohydrates from corn alone. The same applies to potatoes. A “medium” potato is 2.5 to 3 inches across, smaller than what most restaurants serve.
Fiber offsets some of the carb impact. When you subtract fiber from total carbs (a calculation sometimes called “net carbs”), sweet potatoes drop from 21 grams to about 17.7 grams per 100-gram serving. Cassava, with its low fiber content relative to its carb load, stays nearly as high after the subtraction. Vegetables with more fiber slow the release of glucose into your bloodstream, so the same number of total carbs can have very different effects depending on the source.
Quick Comparison by Serving
- Cassava (3.5 oz cooked): 40 g carbs
- Acorn squash (½ cup baked): 30 g carbs
- Russet potato (1 medium): 30 g carbs
- Corn (1 large ear): ~30 g carbs
- Butternut squash (½ cup baked): 21.5 g carbs
- Sweet potato (3.5 oz): 21 g carbs
- Green peas (½ cup): ~15 g carbs
- Parsnips (½ cup): ~15 g carbs
For comparison, most non-starchy vegetables like spinach, broccoli, cauliflower, and bell peppers contain between 3 and 7 grams of carbs per cup. You’d need to eat several cups of broccoli to match a single medium potato.
Choosing High-Carb Vegetables Wisely
None of these vegetables are “bad.” Potatoes, sweet potatoes, and corn are packed with potassium, vitamin C, and B vitamins. Cassava is a calorie-dense energy source. Winter squash is rich in beta-carotene. The carbs they contain come bundled with nutrients you won’t find in refined grains or sugary snacks.
If you’re managing carb intake for blood sugar control or weight loss, the simplest strategy is portion awareness. Treat starchy vegetables as your carb source for the meal rather than stacking them alongside bread or rice. Pair them with protein and fat to slow digestion. And when possible, choose boiled or roasted preparations over baking, since cooking method influences how quickly starch converts to blood sugar.