You can’t remove carbohydrates from a potato entirely, but you can meaningfully reduce how many of those carbs your body actually digests. The key strategies involve soaking, choosing the right cooking method, and cooling potatoes before eating them. A hot boiled red potato has a glycemic index around 89, while the same potato served cold drops to about 56, a reduction of roughly 37%. That difference comes from changes in the starch structure that happen during cooling.
Why Cooling Changes Everything
Potatoes are mostly starch, and starch comes in two forms: the kind your body breaks down quickly into blood sugar, and a tougher kind called resistant starch that passes through your small intestine undigested, behaving more like fiber. When you cook a potato, heat causes the starch granules to swell and become easy for digestive enzymes to attack. But when you cool that cooked potato, something called retrogradation happens: the starch molecules reassemble into tighter, more ordered crystals that your body can no longer break down efficiently.
This process unfolds in stages. First, the straight-chain starch molecules (which make up about 20-25% of potato starch) rapidly form crystal structures. Then, over hours, the branched starch molecules slowly build around those crystals, creating an increasingly resistant structure. Refrigerating cooked potatoes at around 4°C (standard fridge temperature) for 12 to 24 hours maximizes this effect. The result is a potato with significantly less digestible starch than the same potato eaten hot.
Does Reheating Undo the Benefit?
This is the critical question, and the answer is mixed. The resistant starch formed by straight-chain molecules is fairly heat-stable. Heating it to 90°C (just below boiling) only reduces its crystallinity by about 25%. However, the resistant starch formed by branched molecules is much more fragile and can be fully reversed at temperatures as low as 55°C.
In practice, research shows that reheating boiled potatoes reduces their resistant starch content almost back to freshly cooked levels. So if you’re reheating potatoes, you’ll lose most of the benefit you gained from cooling. The best approach for lowering digestible carbs is to eat potatoes cold or at room temperature. Think potato salad, cold sliced potatoes in a grain bowl, or chilled roasted potatoes tossed with vinaigrette.
Soak Before Cooking
Soaking raw potatoes in cold water pulls surface starch out of the flesh and into the water. You can see this happening: the water turns cloudy as starch leaches out. Soaking for at least 30 minutes makes a noticeable difference. For a greater effect, you can soak cut potatoes in the refrigerator for up to 24 hours, changing the water once or twice.
Cutting potatoes into smaller pieces before soaking increases the surface area exposed to water, which means more starch gets pulled out. Thin slices or small cubes will lose more starch than whole potatoes or large chunks. After soaking, rinse the pieces under fresh water and pat them dry before cooking.
Pick the Right Cooking Method
How you cook potatoes affects how digestible their starch becomes. Boiling and steaming (moist heat methods) actually make starch more accessible to your digestive enzymes compared to dry or fat-based cooking. Research comparing cooking methods found that frying produces lower starch digestibility and a lower glycemic response than boiling. Cooking with fat appears to slow down how quickly enzymes can reach and break apart starch granules.
Among the dry and fat-based methods, deep frying, air frying, and baking with oil or butter all produced similar total digestible starch levels, generally ranging from 60% to 72% of the dry weight. The type of fat matters slightly: potatoes cooked in olive oil tended to have the lowest digestible starch percentages in deep-frying comparisons, though the differences were modest. The practical takeaway is that roasting or air frying potatoes with a small amount of fat will produce a lower glycemic impact than plain boiling.
Leave the Skin On
Potato skin is concentrated fiber. While the flesh of a potato contains about 1.8 grams of fiber per 100-gram serving, the skin itself is roughly 52% fiber by dry weight. Fiber slows carbohydrate digestion and blunts blood sugar spikes, effectively reducing the glycemic impact of the starch you do eat. Peeling potatoes removes this built-in buffer. Skin makes up only 1-2% of the potato’s total weight, so its contribution is modest in absolute terms, but every bit helps when you’re trying to minimize carb impact.
Putting It All Together
The most effective strategy combines several of these techniques. Cut your potatoes into small pieces, soak them in cold water for at least 30 minutes, then roast or air fry them with a little olive oil rather than boiling. After cooking, refrigerate them for 12 to 24 hours and eat them cold. This approach attacks the problem from multiple angles: soaking removes surface starch, cooking with fat reduces digestibility, and cooling converts a portion of the remaining starch into a form your body can’t absorb.
If eating cold potatoes doesn’t appeal to you, the soak-and-roast combination alone still makes a meaningful difference. And choosing waxy potato varieties (like red or new potatoes) over starchy ones (like russets) gives you a slightly lower starting carbohydrate content to work with. A 100-gram serving of boiled potato with the skin contains about 20 grams of carbs and 1.8 grams of fiber, giving you roughly 18 grams of net carbs. You won’t turn a potato into a low-carb food, but you can shift enough of its starch into the resistant category to noticeably soften its effect on your blood sugar.