Does Soaking Potatoes in Water Reduce Carbs? The Scientific Truth

December 7, 2025 •

4 min read

According to nutrition experts, the belief that soaking potatoes significantly reduces their total carbohydrate count is largely a myth. While it does remove surface starch for crispier results, the impact on overall carbs is negligible, making it more about texture than nutrition.

Quick Summary

Soaking potatoes removes only minor surface starch and does not substantially reduce overall carbohydrate content. For better blood sugar management, cooling cooked potatoes to create resistant starch is a more effective method.

Key Points

Soaking removes surface starch: Soaking primarily removes loose starch from the potato's surface, not the bulk of its internal carbohydrates.
Negligible carb impact: The effect of soaking on the potato's overall carbohydrate count is insignificant for nutritional purposes.
Cooling is more effective: A much more powerful method to reduce a potato's glycemic impact is to cook it and then cool it, which creates resistant starch.
Nutrient leaching: Prolonged soaking can cause a loss of water-soluble nutrients, including potassium and Vitamin C.
Culinary benefit: Soaking is best used for culinary purposes, such as achieving a crispier exterior on roasted or fried potatoes.
Resistant starch benefits: Resistant starch, created by cooling cooked potatoes, functions like fiber and is beneficial for gut health and blood sugar control.

The Science Behind Potatoes and Starch

Potatoes are naturally high in carbohydrates, with the majority of these carbs being in the form of starch. Starch is a complex carbohydrate that, when cooked and digested, is broken down into simple sugars (glucose) in the body. The rate at which this happens is measured by a food's Glycemic Index (GI). Foods with a high GI cause blood sugar levels to rise rapidly. For this reason, many people on low-carb diets or managing blood sugar seek methods to reduce the carbohydrate load of potatoes. One of the most common kitchen tricks is soaking cut potatoes in water, which visibly removes some of the starchy residue. But does this culinary technique translate into a meaningful nutritional change?

The Truth About Soaking

Soaking potatoes in cold water does, in fact, draw out some of the excess starch. This is evident by the cloudy appearance of the water after a period of soaking. This surface-level starch removal has several culinary benefits, most notably leading to a crispier texture in dishes like french fries or roasted potatoes. The surface starch that would normally become sticky or gummy during cooking is rinsed away, allowing for a better result. However, the effect on the potato's overall carbohydrate content is minor at best and scientifically insignificant for health purposes. A potato's carbohydrates are stored within its cellular structure, and soaking does not substantially penetrate the cells to remove this internal starch.

Potential Nutritional Downsides of Soaking

While soaking may not effectively reduce carbs, it can cause the loss of other nutrients. Potatoes are a good source of water-soluble vitamins and minerals, such as Vitamin C and potassium. Prolonged soaking can cause these valuable nutrients to leach out into the water, which is then discarded. This practice is sometimes intentionally used by individuals with kidney disease to reduce the potassium content of potatoes, but for the average person, it represents a nutritional loss.

Soaking vs. Creating Resistant Starch

For those genuinely interested in lowering the glycemic impact of potatoes, focusing on how they are cooked and cooled is a far more effective strategy than simply soaking them. This method involves creating resistant starch. Resistant starch is a type of carbohydrate that functions more like fiber and is not easily digested by the body. This means it does not cause a rapid spike in blood sugar levels. The process, known as starch retrogradation, occurs when cooked starches are cooled.

Step-by-Step Guide to Maximizing Resistant Starch

Step 1: Cook the potatoes. You can boil, bake, or steam your potatoes as you normally would.
Step 2: Cool them completely. After cooking, place the potatoes in the refrigerator for at least 12-24 hours. This cooling process is what converts the digestible starch into resistant starch.
Step 3: Reheat if desired. The resistant starch will remain even if the potatoes are reheated. However, this effect is maximized when served cold, like in a potato salad. This process can reduce the potato's GI by 25-28%.

Other Techniques to Modify Glycemic Impact

Beyond cooling, other preparation methods can alter the glycemic response to potatoes:

Choose the right potato variety: Waxy potatoes like red or new potatoes have a lower starch content and naturally lower GI than starchy varieties like Russet potatoes.
Add acidic ingredients: A splash of vinegar or lemon juice can interact with starch molecules and further mitigate their effect on blood sugar levels.
Combine with other foods: Eating potatoes with fiber-rich vegetables, healthy fats, or protein can help slow down the absorption of carbohydrates and prevent blood sugar spikes.

A Comparison of Potato Preparation Methods


Feature	Simple Soaking Method	Resistant Starch Method	Combined Method (Soak & Cool)
Effect on Total Carbs	Negligible reduction	No change in total carbs, but conversion to less digestible form	No change in total carbs, but conversion to less digestible form
Effect on Glycemic Index	Minor or no effect	Significant reduction (25-28%)	Significant reduction (25-28%)
Culinary Benefit	Crispier texture for fries	Enhanced gut health, prebiotic effect	Combines crispy texture with gut health benefits
Nutrient Loss	Can lose water-soluble vitamins (Vit C, Potassium)	Minimal to no loss, depending on initial cooking	Potential loss of water-soluble vitamins from initial soaking
Time Commitment	Quick (30 mins to 2 hrs)	Longer (cooking + 12+ hrs cooling)	Requires both soaking and prolonged cooling

Conclusion: Smart Choices Over Simple Soaks

While the practice of soaking potatoes is useful for improving texture in many recipes, it is not an effective way to significantly reduce the carbohydrate content for health purposes. For those concerned with blood sugar management or glycemic load, focusing on the cooking and cooling process to create resistant starch is a far more robust and scientifically-supported strategy. A simple soak is a culinary tool, not a nutritional shortcut. For further reading on the science of starches and their impact, consult reliable sources like those found at the National Institutes of Health.

Frequently Asked Questions

The reduction in carbohydrates from soaking potatoes is negligible and not considered nutritionally significant. It only removes loose surface starches, not the carbs from the potato's cellular interior.

The main benefit of soaking potatoes is improving their texture. By removing surface starch, it helps prevent stickiness and leads to a crispier finish when fried or roasted.

Resistant starch is a type of carbohydrate that acts like fiber and is not digested by the body. It is formed when cooked potatoes are cooled completely, which is a much more effective way to reduce their glycemic impact.

While the process alters the starch structure, many people find the change in taste or texture to be minimal. Cooled and reheated potatoes, like those used in potato salad, still retain good flavor and a firm texture.

Diabetics may benefit more from creating resistant starch by cooking and cooling potatoes, rather than relying on soaking alone. Always consult a healthcare professional for dietary advice.

Yes, soaking for a prolonged period can cause water-soluble vitamins and minerals, such as Vitamin C and potassium, to leach out into the water. This is particularly relevant for those trying to retain maximum nutritional value.

Waxy potatoes like red or new potatoes have a lower starch content and a lower glycemic index than starchy Russet varieties. Choosing these can be a simple way to reduce starch intake.