It depends on the type. Summer squash varieties like zucchini and yellow squash are very low in carbs, with only about 2 grams of net carbs per 100 grams. Winter squash varieties like butternut and acorn are significantly higher, ranging from 5 to 10 grams of net carbs per 100 grams. The difference is large enough that summer squash fits easily into a keto diet, while winter squash requires more careful portioning.
Summer Squash: The Low-Carb Winner
Summer squash is one of the lowest-carb vegetables you can eat. Per 100 grams (about 3.5 ounces) of raw squash, here’s what you’re looking at in net carbs:
- Zucchini: 2.1 g
- Yellow squash: 2.1 g
- Chayote squash: 2.3 g
- Pattypan squash: 2.6 g
A whole medium zucchini (196 grams) contains just 6 grams of total carbs and 2 grams of fiber, putting net carbs at roughly 4 grams for the entire thing. That’s comparable to leafy greens. Five grams of those total carbs come from natural sugars, with very little starch. You could eat multiple servings of summer squash in a day and barely make a dent in a 20-gram carb budget.
This is why zucchini noodles became a staple in low-carb cooking. A generous plate of spiralized zucchini has a fraction of the carbs in even a small serving of pasta.
Winter Squash: Higher but Varies Widely
Winter squash is starchier and sweeter, which pushes the carb count up considerably. But “winter squash” covers a wide range, and some varieties are much more manageable than others. Net carbs per 100 grams, raw:
- Hubbard squash: 4.8 g
- Spaghetti squash: 5.4 g
- Sugar pumpkin: 6.5 g
- Kabocha squash: 7 g
- Delicata squash: 7 g
- Acorn squash: 8.9 g
- Butternut squash: 9.7 g
A medium winter squash (200 grams) contains about 23 grams of total carbs and 4 grams of fiber, so roughly 19 grams of net carbs for the whole thing. That’s a meaningful amount if you’re aiming for 20 to 50 grams per day. Butternut and acorn sit at the top of the carb range, while spaghetti squash and hubbard are closer to the middle ground.
Spaghetti Squash as a Pasta Substitute
Spaghetti squash deserves a separate mention because it’s the winter squash most often used in low-carb meals. One cup of cooked spaghetti squash provides about 10 grams of total carbs and 42 calories. Compare that to a cup of cooked pasta at roughly 43 grams of carbs. You’re cutting the carb load by more than 75% with the swap.
At 5.4 grams of net carbs per 100 grams raw, spaghetti squash sits in a gray zone. It’s not as free as zucchini, but a reasonable portion works fine in most low-carb plans. If you’re on strict keto (under 20 grams daily), you’d want to keep portions to about a cup and account for it in your daily total.
Blood Sugar Impact
Carb count alone doesn’t tell the whole story. How quickly a food raises your blood sugar matters too. Boiled butternut squash has a glycemic index of 51, which falls in the low category (under 55). So even though butternut has more carbs than summer squash, it doesn’t cause a sharp blood sugar spike. Kabocha squash has a lower glycemic load than sweet potato and pumpkin, making it another reasonable option for people watching blood sugar levels.
Summer squash, with its minimal carb content, has a negligible effect on blood sugar regardless of how it’s measured.
How to Fit Squash Into a Low-Carb Diet
If you’re eating under 20 grams of net carbs per day, summer squash is essentially unlimited. Zucchini, yellow squash, and chayote can be used freely as side dishes, in stir-fries, or as noodle replacements without serious carb tracking.
Winter squash takes more planning. A half-cup serving of butternut squash adds roughly 5 to 6 net carbs, which is workable but not trivial on a strict plan. If you’re on a more moderate low-carb approach (50 to 100 grams daily), winter squash fits comfortably as a side dish or soup base. Roasted acorn squash or a bowl of butternut soup won’t push you over your limit as long as you’re not pairing them with other starchy foods in the same meal.
For the best of both worlds, spaghetti squash and hubbard squash give you the flavor and heartiness of winter squash with net carbs that stay closer to the 5-gram range per 100 grams. They’re the easiest winter varieties to work into a stricter plan.