Can Cornstarch Be Used as a Low-Carb Sauce Thickener?

Thickening Agents You Can Use That Are Low in Carbs

Cornstarch in a pile with a wooden spoon
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Thickening a sauce, stew, gravy, or soup can be tricky when you are limiting carbohydrates. And in addition to determining which thickener is best for your diet, you also need to know how much to use. Traditional thickening agents such as flour or cornstarch may work if you only need a small amount, or a lower-carb starch alternative may be preferable when a recipe calls for more thickener or contains other carb-heavy ingredients.

No matter what your carb intake goals are, there is a thickening agent that will work for any dish you're preparing.

White or Whole Wheat Flour

White flour is the most common thickener used in sauces and in some recipes, you might be fine using it. There are 6 grams of carbohydrates per tablespoon of white flour, which will thicken one cup of a gravy (which has some thickeners from the meat), or a thin sauce. It takes two tablespoons of flour to thicken a sauce to medium thickness, and three for a thick sauce.

Whole wheat flour has 4.5 grams net carbohydrates plus 1 gram fiber per tablespoon, though you usually need slightly more wheat flour than white flour to thicken a sauce, and it may slightly alter the flavor of the dish you add it to. Gluten-free flours such as rice flour work the same way as wheat flour when it comes to thickening sauces, and have approximately the same amount of carbs.

When you use flour to thicken a sauce, you cannot add it directly as it will create lumps. The best way to add it is in a roux, where you heat it with a fat, like oil or butter, and cook it for a minute or two (stirring constantly) to get rid of the raw flour taste. Then, whisk in the liquid.

A roux will slowly get darker the longer you cook it. Some recipes will call for a darker roux, but the thickening power of flour decreases as the roux cooks, so for low-carb purposes, a white roux is best.


Cornstarch has 7 grams of carbs per tablespoon, but more thickening power than flour, so you can often use less than what the recipe calls for. According to cornstarch manufacturers, you only need half as much cornstarch as flour to achieve the same thickening results, though some cooks may question this claim.

If your recipe only calls for one tablespoon of a thickener, then cornstarch might a low-carb option for you.

Sauces thickened with cornstarch are less opaque and glossier than ones with flour. Cornstarch is generally added to cold water and then to the sauce (whisk or shake in a small container to combine), and you do not have to worry about cooking it first.

Arrowroot Flour

If you are looking for an easy way to thicken a sauce without changing the taste of your food, turn to arrowroot flour instead of cornstarch, which can leave foods tasting chalky if undercooked.

Arrowroot flour is a fine white powder made from dried tubers. It is similar to cornstarch in the number of carbs it has and is used the same way, except it has a glossier appearance. It also stands up to acidic liquids better than cornstarch does.

When used in cooking, arrowroot flour has twice the thickening power of wheat flour, but unlike wheat flour, it does not alter the flavor of the food.

Use arrowroot flour to thicken sauces that should remain clear, and note that while it freezes well, it does not reheat successfully and cannot be used at high temperatures or in recipes that involve long cook times.

Alternatives to Starch

If you want to avoid using starches as thickening agents altogether, there are a few alternatives, like vegetables, dairy products, eggs, nuts, and seeds. The choice of alternative you can choose depends on what you need to cook and any other dietary restrictions.

Vegetable Gums

With names like guar gum and xantham gum, vegetable gums may not sound appetizing, but don't let their names scare you. Both thickeners are made from vegetable fiber that absorbs water to make a gel-like, viscous consistency. Unlike flours, vegetable gums are gluten-free and are often used as thickeners in commercial products. These thickeners can be found in health food stores or online.

To use vegetable gums to thicken sauces, sprinkle a small amount into the sauce while whisking. Go slowly, because too much will over-thicken the sauce and leave a slick feel to the food.

Pureed Vegetables

Pureed vegetables are especially good for creamy soups and also work well for sauces. Almost any cooked vegetable can be blended and used to thicken a soup or sauce, but consider how the flavors will work together; for example, pureed broccoli would probably taste good as a thickener for pumpkin soup. Tomato paste is a good thickener that will taste good with many recipes, or eggplant, zucchini, other squash, cauliflower, or lower carb root vegetables are all excellent choices when you do not want the vegetable puree to add too much flavor.

Dairy Products

Cream will thicken as it reduces, so if you add cream to a sauce and boil it, the sauce will thicken more than it will if reducing without the cream.

Sour cream is an already thickened version of cream and it can be whisked into a sauce. Cream cheese, which is thicker than sour cream, can also be used as a thickener, although it imparts a distinctive flavor.

Also, you can add cold butter at the end of cooking a pan sauce and that will have a thickening effect.


Egg yolk mixed with a fat is an effective thickener; imagine the consistency of mayonnaise or hollandaise, which are made with oil or butter and egg yolk. As a rule, do not add yolk directly to a hot sauce or it will scramble. To avoid this, temper the yolk by adding a small amount of the sauce to it to gradually bring it up to temperature. Then, add the tempered yolk to the sauce.


Ground nuts were traditionally used to thicken sauces in the days of old, and they still work today. Nut butters, like peanut and almond, also work well. Coconut butter is another option, or you can buy jars or cakes of concentrated coconut cream that can be used for thickening sauces. However, do not confuse these with similarly-named coconut drink mixes, as they have added sugar.


Flaxseed meal and chia seeds expand and thicken liquids, but they can be grainy, so they do not work well in many sauces. However, they can work well to thicken drinks like juices, turning them into shakes.

A Word From Verywell

With a few new kitchen tricks, you will be able to enjoy sauces, soups, and gravy that are lower in carbohydrates, but still have the thick consistency you're looking for. You may even discover you enjoy these variations more than the traditional methods and be happy you explored your options.

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