Potatoes are some of the highest-GI foods you can eat. Baked russets test at 85 and instant mashed at 87, higher than table sugar (65). Sweet potatoes aren’t the automatic fix they’re made out to be: boiled they test at 63, baked at 94. The starchy vegetables that come in low are peas, corn, butternut squash, parsnips, and tropical roots like cassava, taro, and true yams.
Below are GI and GL values for 18 potatoes and starchy vegetables, the swaps that matter most, and a shopping list you can print.
- Potato and starchy veg GI table
- What makes potatoes lower
- Best and worst picks
- Smart swaps
- Shopping list
- Tips
- FAQ
- Printable
Lowest GI: boiled cassava (46)
Highest: baked sweet potato (94)
Biggest surprise: boiled sweet potato (63) beats baked (94) by 31 points. Same vegetable, different cooking.
Glycemic index of potatoes and starchy vegetables: 18 compared
| Vegetable | GI | GL | Serving | Fits these plans | |
|---|---|---|---|---|---|
 |
Cassava (yuca), boiled | 46 | 12 | 100 g | Low-GI, South Beach P2, Mediterranean |
 |
Butternut squash | 51 | 4 | 80 g | Low-GI, South Beach P2, Mediterranean, Diabetes-friendly |
 |
Green peas | 51 | 4 | 80 g | Low-GI, South Beach P2, Mediterranean, Diabetes-friendly |
 |
Parsnips | 52 | 6 | 80 g | Low-GI, South Beach P2, Mediterranean, Diabetes-friendly |
 |
Sweet corn | 52 | 8 | 80 g | Low-GI, South Beach P2, Mediterranean, Diabetes-friendly |
 |
Taro, boiled | 53 | 14 | 150 g | Low-GI, South Beach P2, Mediterranean |
 |
Yam, boiled True yam, not sweet potato |
54 | 19 | 150 g | Low-GI, South Beach P2, Mediterranean |
 |
New potatoes, boiled Lowest-GI potato |
57 | 12 | 150 g | — |
 |
Sweet potato, boiled | 63 | 18 | 150 g | Mediterranean |
 |
French fries Fat slows digestion |
64 | 19 | 150 g | — |
 |
Beets Medium GI, low GL |
64 | 4 | 80 g | Mediterranean |
 |
Pumpkin Medium GI, very low GL |
64 | 3 | 80 g | Mediterranean |
 |
Rutabaga High GI, low GL |
72 | 7 | 150 g | Mediterranean |
 |
Potato, boiled (white) | 78 | 16 | 150 g | — |
 |
Potato, mashed | 83 | 17 | 150 g | — |
 |
Potato, baked (russet) | 85 | 26 | 150 g | — |
|
Potato, instant mashed | 87 | 17 | 150 g | — |
 |
Sweet potato, baked Highest GI here |
94 | 26 | 150 g | — |
Sorted lowest to highest GI. GI: low 55 or less, medium 56–69, high 70+. GL per serving: low 10 or less, medium 11–19, high 20+. 150 g is about one fist-sized potato; 80 g is about half a cup. None of these fit keto or Atkins Phase 1 except small portions of pumpkin.
What makes one potato lower than another
Cooking method. Baking and roasting break down starch more than boiling does. Sweet potato tests at 63 boiled and 94 baked; a russet tests at 78 boiled and 85 baked.
Variety. Small waxy potatoes (new, red, fingerling) hold their structure when cooked and test at 57. Floury russets turn fluffy, and that fluff digests fast.
Mashing and processing. The more a potato is broken down before you eat it, the faster it’s absorbed. Mashed potatoes test at 83, instant mashed at 87.
Fat. French fries (64) test lower than a baked potato because the frying fat slows digestion. That’s a quirk of the test, not a reason to choose fries.
Carb density. Pumpkin, beets, and rutabaga have a medium-to-high GI but little carbohydrate per serving, so their GL stays at 3–7. They’re easy sides to keep.
Best and worst picks
Best picks (GI 55 or less)
- Cassava (46)
- Butternut squash (51)
- Green peas (51)
- Parsnips (52)
- Sweet corn (52)
- Taro (53)
- Yam (54)
Fine in normal portions
- New potatoes (57)
- Sweet potato, boiled (63)
- Beets (64, GL 4)
- Pumpkin (64, GL 3)
- Rutabaga (72, GL 7)
Limit (GI 70+ and higher GL)
- Sweet potato, baked (94)
- Instant mashed potatoes (87)
- Baked russet potato (85)
- Mashed potatoes (83)
- Boiled white potato (78)
Smart swaps
| Instead of | Try | The difference |
|---|---|---|
| Baked russet potato | Boiled new potatoes | GL 26 → 12 |
| Baked sweet potato | Boiled or steamed sweet potato | GI 94 → 63 |
| Mashed potatoes | Mashed cauliflower, or half and half | GL 17 → near zero (all cauliflower) |
| Instant mashed potatoes | Mashed butternut squash | GI 87 → 51 |
| Boiled white potato as a side | Green peas or sweet corn | GI 78 → 51–52 |
Low-GI starchy vegetable shopping list
- Small waxy potatoes: new, red, or fingerling
- Sweet potatoes, for boiling or steaming
- Butternut squash
- Frozen green peas
- Sweet corn, fresh or frozen
- Parsnips
- Cassava, taro, or true yam, if your store carries them
Reading the label:
- In US stores, the orange “yams” are usually sweet potatoes. True yams have rough, bark-like skin and white flesh, and are mostly found in international markets.
- Instant potato flakes and frozen fries are processed for speed, which pushes the GI up.
- Frozen peas and corn are as good as fresh and keep for months.
Tips to help you succeed
- Boil, don’t bake. I cut sweet potatoes into chunks and boil or steam them rather than baking them whole. It’s the single biggest difference on this page.
- Cook ahead and chill. Potatoes that are cooked and cooled form some resistant starch, which may soften their effect. Potato salad made the day before is a good use for it.
- Add vinegar. A vinegar-based dressing on potato salad has been shown in small studies to lower the blood sugar response.
- Mash half and half. I mash potatoes half and half with cauliflower. Most people at the table don’t notice.
- Treat potatoes as a side. One fist-sized potato is a serving. Fill the rest of the plate with protein and non-starchy vegetables.
How I cook potatoes
Potatoes are a side, not the base of the meal, at my table. I buy small red potatoes, boil them with the skins on, and often serve them cold in a vinegar-dressed potato salad. Frozen peas and corn fill in when I want something starchy and quick.
Frequently asked questions
Are sweet potatoes low glycemic?
It depends on how you cook them. Boiled sweet potato tests at 63, in the medium range. Baked, it jumps to 94, higher than a baked russet. True yams, a different vegetable, test at 54.
Which potato has the lowest glycemic index?
Small waxy potatoes, such as new, red, or fingerling, boiled with the skin on. They test at 57. Floury russets are the highest, especially baked (85) or mashed (83).
Is corn high glycemic?
No. Sweet corn tests at 52, in the low range, with a GL of 8 per half cup. Green peas are similar at 51.
Does cooling potatoes lower their GI?
Somewhat. Cooling cooked potatoes turns some of their starch into resistant starch, and studies show a smaller blood sugar rise from cooled potatoes. It helps, but a cold russet still isn’t a low-GI food.
Can you eat potatoes on South Beach or keto?
South Beach Phase 1 excludes potatoes and other starchy vegetables. From Phase 2, sweet potatoes, peas, corn, and squash come back in moderation; white potatoes are still best kept occasional. Potatoes don’t fit keto: one medium potato has around 30 g of carbs.
Printable starchy vegetables list
A free one-page version of this list is coming soon. For the full printable set covering every food group, see the glycemic index food lists at Health List Now.
GI values vary between tests. This page is general information, not medical advice. Last reviewed October 2026.