What a Dietitian Wants You To Know About Fiber

Most have heard of it, but few understand it. Fiber seems to be having a moment on social media with posts claiming that fiber is the new protein, but why is it so important? How much do you really need? And how can you avoid common mistakes when trying to get more of it?

Fiber naturally exists in carbohydrate-rich, plant-based foods. It comes in two forms and has a specialized structure and functions.

Soluble fiber, which as its name suggests, is soluble in water and will swell and absorb water when combined with water in the body. Insoluble fiber does not absorb water and therefore behaves differently in the gut when digested.

Added or “functional” fibers are synthetically manufactured and added to foods and dietary supplements to enhance a particular benefit or to improve texture and consistency. These ingredients share some, but not all the characteristics of naturally occurring fibers.

When it comes to fiber intake, Americans fall (very) short of their needs. Year after year, data supports that less than 10 percent of Americans are eating the recommended daily amount.

There are several reasons Americans aren’t getting enough, including lack of knowledge about what fiber does and low intake of fruits and vegetables. And truthfully, eating enough fiber can be challenging.

The scientifically supported recommendations state that women should aim for 25 grams and men should get 38 grams per day. But alas, most people max out at 15 grams or less per day, which means many Americans are missing out on the numerous benefits of a fiber-filled diet.

Now that you’ve got fiber on the brain and may be looking to get a lot more of it, here are eight things this dietitian wants you to know about it.

Fiber Is Undigestible

It sounds strange, but it’s true. Fiber is a non-digestible component of some carbohydrate-rich plant foods. The fiber is not absorbed in the small intestine and therefore continues to travel through the gastrointestinal (G.I.) tract until it (ahem) exits the body. Soluble fiber moves slowly through the G.I. tract, causing beneficial fermentation in the intestines, while insoluble fiber travels through it more quickly which helps prevent constipation.

Fiber Isn’t Just About Sending You to the Bathroom Quickly

It’s a partial misconception that all fiber will send you running to the bathroom. Really, different types of fiber will impact digestion time at varying rates. Ideally a balance of both soluble and insoluble fibers allows for trips to the bathroom that are regular, easy, reliable and comfortable. Fiber’s transit through the G.I. tract also helps you feel fuller longer and promotes the growth and maintenance of healthy bacteria. It is well substantiated by science that the fermentation of fiber in the gut helps to promote healthy bacteria to support a flourishing microbiome. Good gut health has a ripple effect to benefit better immunity and decreased risk of chronic illnesses.

Fiber Intake Should Be Increased Gradually

If you are part of the large group of Americans who need to get more fiber, proceed slowly. Due to the impact on digestion, too much fiber too quickly can lead to gas, bloating, diarrhea and overall G.I. discomfort. When introduced in gradual increments, fiber intake can be increased more comfortably and sustainably.

Fiber Is Everywhere

Fruits and vegetables are just the beginning. Fiber can also be found in whole grains, legumes, seeds and nuts. Some of the best sources of insoluble fiber include potatoes, whole wheat and nuts, while oats, barley, berries and beans are packed with soluble fiber. Many foods contain a combination of both types. For example, the flesh of an apple is plentiful in soluble fiber, while its skin contains insoluble fiber.

Fiber on Food Labels Can be Confusing

Fiber is listed on food labels as “dietary fiber” and is categorized as a portion of the carbohydrate count. Some food manufacturers will differentiate soluble and insoluble fiber on labels, while others will just present a total gram value. Foods with functional fibers boast high fiber counts but may offer less nutrition. For example, a “high fiber” granola bar made with chicory root (a functional fiber) might also contain high amounts of added sugars and few other redeeming nutritional qualities. Instead of choosing foods based solely on fiber count, scan the entire label and ingredient list to choose foods with the most overall nutrition to offer.

Fiber Factors Into “Net Carbs”

Popular in the Keto and low-carb diet worlds, some products display a “net carb” value which is calculated by subtracting grams of fiber and sugar alcohols (if applicable) from the total amount of carbohydrates in the food. The rationale is that since fiber is not digested, it should make the food lower in carbs than the label indicates, but this is not entirely accurate, nor does it mean that the food is nutrient-dense. This is not a term or calculation approved or recognized by the U.S. Food and Drug Administration (FDA), and therefore it’s not worth paying attention to.

Fiber Can Help with Weight Loss

The more fiber in a meal, the longer it takes to digest, which is why fiber is coveted for helping to increase satiety. Feeling full and energized while in a calorie deficit is crucial for long-term success. A study published in 2019 supports that fiber helps people lose weight and stick to their diets. If you are on a weight loss or maintenance journey, eating plenty of high-fiber foods can help fight hunger pangs and cravings.

Fiber Isn’t Just a Fad, It’s Critical for Long Term Health

The fiber in foods helps prevent spikes in blood sugar. This can also lead to a decreased prevalence of type 2 diabetes. You may have heard oat products like cold and hot cereals are beneficial for lowering cholesterol and that’s thanks to the soluble fiber found in oats. Soluble fiber binds to cholesterol in the intestines and prevents some from being absorbed; according to research both foods and fiber supplements containing soluble fiber have been found to be beneficial.