Soy sauce, which is typically used in Asian cuisine, is a staple low calorie condiment with a distinct umami flavor.

If you follow a ketogenic, or keto, diet, you may wonder whether this flavorful ingredient is a good choice.

The keto diet drastically restricts carbs, and some soy sauces contain more carbs than others.

This article discusses soy sauce, its carb content, and whether it’s a keto-friendly condiment.

Several types of soy sauce exist, and they vary by production method and content.

There are two main ways soy sauce is produced — traditionally and chemically.

Traditional soy sauce is brewed by fermenting soybeans and wheat in water and salt using mold, yeast, and bacteria. It’s aged over months — sometimes even years (1).

In a much faster method, soy sauce can be chemically produced in as little as 8–12 hours by breaking down soybeans using high heat and a strong acid solution. (2).

Types of soy sauce also vary based on the proportions of soybeans, wheat, salt, and other ingredients used, including sugar. Along with flavor, texture, and aroma, the ingredients used may affect the carb content and whether the soy sauce is keto-friendly.

The soy sauce commonly used in North America, which is considered to be “light soy sauce,” is typically very low in carbs, as it contains little to no added sugar (3).

However, significant amounts of sugar are added to some varieties of soy sauce, such as “sweet soy sauce,” which is not keto-friendly.

While the exact amount depends on the brand, here are the breakdowns of common types of soy sauce and their typical carb contents:

  • Light soy sauce. Considered the most familiar type in North America, this variety typically contains around 1 gram of carbs per tablespoon (15mL) or less (3).
  • Dark soy sauce. This variety may be slightly sweetened, giving it around 1–5 grams per tablespoon (15mL) (4, 5).
  • Tamari. This variety is commonly gluten-free and typically contains 1 gram of carbs per tablespoon (15mL) (6).
  • Sweet soy sauce. Also known as “kecap manis,” this variety is typically high in added sugar. Depending on the brand, each tablespoon (15mL) may contain up to 15 grams of carbs (7, 8).
Summary

The number of carbs in soy sauce typically ranges from 1–15 grams per tablespoon (15mL), depending on the type and brand.

Though there are many variations of the keto diet, they all involve restricting carbs to promote ketosis — a metabolic state in which your body mainly burns fat for fuel instead of carbs (9).

Research suggests ketosis can be achieved by most people by reducing carb intake to 10% or less of your daily carb intake, or roughly 20–50 grams per day (10).

Given that many soy sauces are low carb, it’s possible to enjoy this flavor-enhancing condiment without pulling yourself out of ketosis.

Yet, there are a few important things to consider:

  • Carb content. The carbs in soy sauce can range from 1–15 grams per tablespoon (15 mL). Check the nutrition facts label to determine how many carbs your soy sauce contains per serving.
  • Portion size. The nutrition label usually reports carbs per tablespoon (15 mL) of soy sauce. For reference, a single soy sauce packet contains around 1 teaspoon (5 mL), or one-third of a tablespoon. Monitor how much you use to ensure it aligns with your dietary goals.
  • Carb allowance. Based on the carb content of your soy sauce, determine whether the portion size you use fits within your overall carb allowance for the day.

Another rule of thumb is to avoid any soy sauce described as “sweet.” These typically contain added sugar and are likely not keto-friendy.

Keep in mind that soy sauce is a common ingredient in Asian cuisine. When dining out, consider asking for an unsweetened soy sauce on the side to better manage the type and portion you consume.

Summary

Most soy sauce is low in carbs and can be used on a keto diet. Check the nutrition facts label to determine whether the number of carbs fits within your daily allowance.

Many individuals choose to sub soy sauce with similar tasting condiments due to allergies, gluten intolerance, or other dietary concerns.

As with soy sauce itself, some soy sauce alternatives are more keto-friendly than others.

Here is the carb content of several soy sauce substitutes:

  • Liquid aminos. When made from soy protein, liquid aminos contain 0 grams of carbs per tablespoon (15mL) (11).
  • Coconut aminos. Liquid aminos derived from coconut contain more carbs than most soy sauces. Each tablespoon (15 mL) of coconut aminos contains around 6 grams of carbs (12).
  • Maggi seasoning sauce. Similarly to light soy sauce, Maggi seasoning sauce contains less than 1 gram of carb per tablespoon (15mL) (13).
  • Fish sauce. As a small amount of sugar is usually added, 1 tablespoon (15 mL) of fish sauce typically contains around 1 gram of carbs or less (14). Fish sauce contains more sodium than soy sauce, so it’s typically not a 1-to-1 alternative.

Like soy sauce, most soy sauce alternatives can easily be enjoyed on a keto diet as long as the number of carbs and portion size are considered in relation to your overall daily carb allowance.

Summary

Many soy sauce alternatives are keto-friendly. Check the nutrition label to be certain the carb content per serving does not exceed your daily carb limit.

You don’t need to exclude all soy sauces on a keto diet, as there are many low carb options to choose from.

For example, many varieties only contain around 1 gram of carbs per tablespoon (15 mL).

However, some varieties may contain significant amounts of carbs from added sugar. For example, sweet soy sauces may contain up to 15 grams of carbs per tablespoon (15 mL), which is not a keto-friendly amount.

To prevent pulling yourself out of ketosis, determine the number of carbs in your soy sauce by checking the nutrition label. Monitor your portion sizes to ensure you don’t exceed your daily carb limit.