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Is Cornstarch Keto-friendly or Bad for Your Health?


When you think of cornstarch, a number of different uses may come to mind. Maybe you’ve used it as a helpful replacement for baby powder or have added it as a thickening agent for your gluten-free baking recipes. But you may still be wondering, “Is cornstarch bad for you?” This guide will answer that question and more.


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What Is Cornstarch?

It’s strange to think that a substance used for industrial products such as latex gloves could also be edible. But it’s true.

Cornstarch is a fine, white powder made from the endosperm of corn kernel seeds. The endosperm is where you’ll find all the starch in the kernel.

This starch is what led to its discovery in 1840 in a wheat starch factory in Jersey City, New Jersey, back in 1840. It was used strictly for industrial purposes until it started to become incorporated into food production in 1851.

While cornstarch is a fine powder with multiple uses, it doesn’t have any real nutritional value. It provides no protein, healthy fats, vitamins, or minerals.

One cup of cornstarch contains[*]:

  • 488 calories
  • 0 grams of fat
  • 0 grams of protein
  • 117 grams of carbohydrates
  • 2 grams of fiber

When it comes to recipes, cornstarch is mainly used for thickening sauces, soups, stews, custards, and other liquid-based dishes. Some people prefer cornstarch over wheat flour because of its translucent color and lack of flavor, but the high carb count is an important factor to take into consideration. So the question remains — is cornstarch bad for you?

Is Cornstarch Bad for You?

To figure out if cornstarch is bad for you on the keto diet, take a look at how much you would use in a typical recipe and see if the carb count is too high.

You can measure this by how much flour you would use for any given recipe. When replacing flour, you only need to use half the amount of cornstarch. For example, a recipe requiring one cup of flour would only need a half cup of cornstarch.

It’s important to keep in mind that a one half-cup serving of cornstarch includes over 58 grams of net carbs. This means even a quarter-cup of this thickener is enough to kick you out of ketosis.

The standard ketogenic diet (SKD) suggests that you stay between a carb intake of 20 and 50 grams per day, and often even less than that. The SKD is the go-to version for those just starting a low-carb or ketogenic diet.

Starting off with a carb deficit is important in altering your metabolism. When you consume carbs, your body naturally looks to burn them for energy. However, when you deprive yourself of carbs, your body looks to its second preferred fuel source — fats.

Considering that you want to stay under 20 grams of carbs per day, cornstarch could easily impact your keto goals. On top of its high carb count, it simply has no additional health benefits — giving you no real reason or need to consume it.

Different Types of Keto Diets That Allow a Higher Carb Intake

There are other types of ketogenic diets that could allow the consumption of cornstarch. The targeted ketogenic diet (TKD) is meant for people who lead a more active lifestyle and require a bit more carbs to fuel their workouts.

The TKD allows for 20 to 50 additional grams of carbohydrates up to both an hour before and after the workout window.


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For people who train at extremely high intensities, this simply may not be enough carbs. This is where the cyclical ketogenic diet (CKD) comes into play.

The CKD follows an SKD for the majority of the week (about five days a week) and then has up to one to two days of carb backloading.

During these two days of carb backloading, you can consume up to 400 to 600 grams of carbohydrates in order to completely refuel your glycogen stores. This is the time when consuming cornstarch would potentially fit, but certainly not in large amounts.

When Should Cornstarch Be Avoided on a Low-Carb or Keto Diet?

While you may think cornstarch is good for you since it’s originally from a planted crop, the truth is that it’s not. The only possible health benefit cornstarch may provide is if you’re consciously trying to gain weight.

With its lack of flavor and high calorie count, it’s an easy way to get in those extra calories and boost your insulin levels. However, most people should be cautious of consuming too much of this thickening agent.

While you should avoid using this ingredient if you’re following a low-carb or standard ketogenic diet, you should also be careful consuming it on the targeted ketogenic diet.

With a quarter-cup serving being around 24 grams of net carbs, this tiny bit of cornstarch may still be enough to kick you out of ketosis even if you’re trying to use those carbs to fuel your workout.

Other Gluten-Free Flours to Avoid on a Keto Diet

If you’re seeking gluten-free baking options, you’ll probably notice that cornstarch is a common thickening agent. You might also see the following options, which could negatively impact your keto goals. What to do? Avoid them altogether.

  • Arrowroot: One cup includes 113 grams of carbs and 457 calories[*]
  • Tapioca Flour: Also called tapioca starch, this flour has 728 grams of carbs in just one ounce[*]
  • Potato Starch: One ounce has 23.3 grams of carbs and no fiber[*]
  • Cornflour: A one-cup serving includes 89.9 grams of carbs[*]
  • Rice Flour: This flour has 127 grams of carbs in one cup[*]
  • Cassava Flour: There are 108 grams of carbs in one cup[*]

Low-Carb Cornstarch Substitute

If you are trying to turn a recipe that calls for cornstarch into a keto-friendly option, both almond flour and coconut flour are good substitutes. You might need to use xanthan gum to help it all stick together. Most gluten-free recipes use xanthan gum, so it’s a good idea to have some on hand.

The Takeaway

Eating cornstarch won’t harm you, but it could lead to weight gain or kick you out of ketosis.

If you’re thinking of adding cornstarch into one of your favorite low-carb dishes, think again. While it’s commonly seen in many recipes today, it’s simply not suitable for a low-carb or ketogenic diet.

Luckily, there are low-carb substitutes for cornstarch — particularly, almond flour and coconut flour — that you can choose from.

While there are some circumstances in which the keto diet would allow you to have a higher number of carbohydrates, that’s only during the carb-backloading days if you are following the TKD or CKD. Your other days on the ketogenic diet should be kept between 20 and 50 grams of carbohydrates, or even less.


Join 90k+ people who are losing weight with Keto Kickstart, our doctor-developed program designed to give you real weight loss results.

The first step is making sure you’re within your macronutrients. You can calculate them correctly with the free Perfect Keto calculator.


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