Out of Cornstarch, one case

Keto cornstarch substitute

5 options, ranked, with the exact amount

Use thisBest of 5 options

Use Xanthan gum

¼ tsp for every cup liquid

For thickening on a keto diet, use xanthan gum: ¼ tsp per cup of liquid, in place of the 1 tbsp cornstarch that cup would have needed. Sprinkle it in while whisking and wait a minute before adding more. Cornstarch has about 7 g of carbohydrate per tablespoon; that much xanthan gum adds well under 1 g. For breading, where cornstarch was a coating, use almond flour or crushed pork rinds instead. Arrowroot, tapioca starch, potato starch and flour are not low-carb.

Verdict —: You'll taste it
The tweak —: Sprinkle it over the surface in a thin stream while whisking hard, or blend it in. Wait a full minute before deciding whether to add more.
Best for —: gravy, pan sauces and soups
Pantry —: Special trip

One casethe full cornstarch card

Every option, one card

Ranked

Cornstarch substitutes compared
#	Substitute	Instead of cornstarch	Verdict
1	Xanthan gumgravy, pan sauces and soups	¼ tsp per cup liquidYou'll taste it	You'll taste it
2	Guar gumcold sauces, smoothies and ice cream bases	¼ tsp per cup liquidYou'll taste it	You'll taste it
3	Glucomannan powderhot soups, stews and gravies	¼ tsp per cup liquidYou'll taste it	You'll taste it
4	Unflavored gelatinketo puddings, cream pies and panna cotta	1 envelope per 2 cups liquidYou'll taste it	You'll taste it
5	Almond flour for breadingpan-fried chicken cutlets and fish	Same amountYou'll taste it	You'll taste it
Not a swap	Arrowroot, tapioca or potato starch	not a swapNot for this	Not for this

What changesWhat changes, option by option5 options

Xanthan gum

none; the sauce feels slightly slippery where cornstarch feels silky

A powdered thickener made by fermentation. It is far stronger than cornstarch, works hot or cold with no cooking, and nearly all of its carbohydrate is fiber.

Best for: gravy, pan sauces and soups, sauces that will be reheated, cold sauces and dressings
Prep: Sprinkle it over the surface in a thin stream while whisking hard, or blend it in. Wait a full minute before deciding whether to add more.
Suits: keto, vegan, gluten-free
Where it fails: It thickens but does not set, so it will not make a pudding or pie filling that holds a slice. Too much turns stringy and cannot be removed.

Measure it level. Doubling a quarter teaspoon is enough to take a sauce from right to slimy.

Guar gum

faintly beany in large amounts

A thickener ground from guar beans that behaves much like xanthan gum and is also mostly fiber. It is at its best in cold mixtures.

Best for: cold sauces, smoothies and ice cream bases, soups and gravies when you have no xanthan gum
Prep: Start with ¼ tsp per cup, whisked or blended in, and add more a pinch at a time.
Suits: keto, vegan, gluten-free
Where it fails: Acidic sauces with a lot of lemon or vinegar, where it thickens weakly, and anything that has to set firm.

Glucomannan powder

none

Konjac root fiber, the same ingredient as shirataki noodles. It thickens strongly and keeps thickening as it sits and as it heats.

Best for: hot soups, stews and gravies, sauces that simmer
Prep: Start with ¼ tsp per cup, sprinkled into the liquid while whisking, give it a few minutes of simmering and add more only if it is still thin.
Suits: keto, vegan, gluten-free
Where it fails: It keeps firming up as it cools, so a sauce that was right in the pan can turn to a soft jelly in the refrigerator. Never swallow the dry powder; it swells.

Unflavored gelatin

none; the set is a clean gel, not a creamy starch-thickened pudding

For the setting job that the gums cannot do. One envelope sets 2 cups of liquid to a firm gel once chilled, and it has no carbohydrate.

Best for: keto puddings, cream pies and panna cotta, no-bake cheesecake fillings
Prep: Sprinkle it over ¼ cup cold liquid, let it stand 5 minutes, then stir it into the hot mixture until dissolved. Chill at least 4 hours.
Suits: keto, gluten-free
Where it fails: It does nothing for a hot sauce or gravy: gelatin only sets when cold and melts again when warmed. It is not vegetarian.

Almond flour for breading

nutty and rich; browner and softer than a cornstarch crust

Where cornstarch was a dredge for frying, finely ground almond flour coats in the same amount. It browns fast and gives a nutty, tender crust. Crushed plain pork rinds are the other common keto coating and have no carbohydrate.

Best for: pan-fried chicken cutlets and fish, air-fryer and oven breading
Prep: Pat the food dry, dip it in beaten egg so the coating sticks, and fry at medium heat: almond flour burns sooner than starch.
Suits: keto, gluten-free
Contains: tree nuts
Where it fails: It will not thicken a sauce: it has almost no starch and stays gritty. It also does not give the thin, glassy crunch of a starch coating.

Almond flour has roughly 5 to 6 g of carbohydrate per ¼ cup, about half of it fiber. Check the label on your bag.

Arrowroot, tapioca or potato starch

neutral taste

These are the usual cornstarch substitutes, and they are all nearly pure starch, with about as much carbohydrate per tablespoon as cornstarch itself.

Best for: cooking that is not low-carb
Where it fails: On a keto diet they save nothing. Flour is no better: it has a little less carbohydrate per spoonful, but it takes twice as much to thicken.

How it behaves in this recipe

In this recipeCornstarch

Cornstarch is close to pure starch, about 7 g of carbohydrate in each tablespoon, so the usual swaps for it are no lower in carbs. A keto replacement has to come from a different family: gums and fibers for thickening, gelatin for setting, and nut flour or pork rinds for coating. No single one does everything cornstarch does, so pick by the job.

Tips for substituting cornstarch

5 tips

Xanthan gum: ¼ tsp per cup of liquid, sprinkled in while whisking. Wait a full minute before adding more, because it keeps thickening after you stop.
Never tip a gum in as a spoonful. It forms a lump with a dry center that will not dissolve. A blender or a fine sieve held over the pan spreads it evenly.
Simmering a sauce uncovered until it reduces, or finishing it with a spoonful of cream cheese, heavy cream or cold butter, thickens it with no added thickener.
For a pudding or pie that has to set, use gelatin, 1 envelope per 2 cups of liquid, and chill at least 4 hours.
For breading, press almond flour or crushed pork rinds onto food dipped in egg, and cook at medium heat so the coating does not scorch.

Questions

5 questions

How many carbs are in cornstarch?

About 7 g of carbohydrate per tablespoon, with almost no fiber. A tablespoon thickens roughly 1 cup of liquid, so the carbohydrate is spread across however many servings that cup makes.

How much xanthan gum replaces 1 tablespoon of cornstarch?

Start with ¼ tsp, which thickens about 1 cup of liquid, the same job 1 tbsp of cornstarch does. For 2 tbsp cornstarch in 2 cups of liquid, use ½ tsp. Add it gradually; it is easy to overshoot.

Is arrowroot keto?

No. Arrowroot is nearly pure starch, like cornstarch, with about the same carbohydrate per tablespoon. The same is true of tapioca starch and potato starch. They are grain-free, which is not the same as low-carb.

What is a keto breading substitute for cornstarch?

Almond flour or crushed plain pork rinds, used in the same amount as a coating over an egg wash. Pork rinds have no carbohydrate and fry up crunchier; almond flour gives a softer, nutty crust. Neither makes the thin, glassy shell that cornstarch does.

Can I use almond flour or coconut flour to thicken a sauce?

Not well. Almond flour has very little starch and leaves a gritty sauce that never turns smooth. Coconut flour soaks up liquid and makes a sauce pasty and coconut-flavored. Use a gum for sauces and keep the nut flours for breading and baking.