Why There Are Calories in Soluble Fiber


Verywell / Alexandra Shytsman

Soluble fiber is a little different from insoluble fiber. Soluble fiber can dissolve in or be absorbed by water, whereas insoluble fiber cannot.

What that means for your low-carb diet is simple. When considering dietary fiber, which is derived from plants such as fruits and vegetables, of the two types of fiber, insoluble fiber doesn't have calories because it "goes right through." However, soluble fiber does count calorie-wise.

What Is Soluble Fiber?

Soluble fiber includes gums, pectins, mucilages, and some hemicelluloses. According to the FDA, soluble fiber is listed on food labels as having calories because it does, in a roundabout way, contribute calories to the body. This is because the bacteria in the gut use soluble fiber to produce short-chain fatty acids, which, in turn, are used by the body as energy.

These calories typically do not raise blood sugar, so if you follow an intensive insulin regimen where you are calculating insulin doses based on carbohydrates, you may want to subtract the total fiber from the carbohydrates to determine the number of available carbohydrates that can affect your blood sugar.

This can be complex, so if you have questions or are confused, it's a great idea to talk to your health care provider or registered dietitian.

What Is Insoluble Fiber?

Insoluble fiber includes cellulose, some hemicellulose, and lignins. You can find it in the seeds and skins of fruits and vegetables and whole grains like whole wheat and brown rice. The body cannot use it for energy.

Insoluble fiber is referred to as "roughage" and has several health benefits, including staving off hunger and keeping your bowel movements regular.

Health Benefits of Soluble Fiber

Higher dietary fiber is associated with lower weight and less cardiovascular disease. And while insoluble fiber is known to improve immune function and reduce the risk of diverticulitis, soluble fiber has benefits as well.

Soluble fiber is known to increase good bacteria in the gut, which improves digestive health. Another positive of soluble fiber is its ability to slow down digestion, which helps you maintain that full feeling after a meal longer. The slowdown in digestion is good for you if you're on a low-carb diet as it will help you control your appetite.

Foods High in Soluble Fiber

Americans typically only get about half of the recommended amount of 25 to 38 grams of dietary fiber a day. The most popular sources of fiber in the American diet are processed flours, grains, and potatoes. The least popular are fruits, legumes, and nuts. Here are fiber-filled foods to add to your low-carb diet:

  • Oatmeal
  • Legumes such as peas, beans, and lentils
  • Barley
  • Fruits and vegetables, especially oranges, apples, and carrots
5 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Laura Dolson
Laura Dolson is a health and food writer who develops low-carb and gluten-free recipes for home cooks.