February 5, 2022

Fiber: Top 10 Questions Answered

We talk fiber A LOT with clients. We even give a specific fiber score to our 1:1 clients as part of their Personalized Nutrition Analysis. We talk about it so much so that those conversations have inspired this blog post today! 

We are going through some common questions we get about fiber so that you can walk away with a clearer understanding of what exactly fiber is, what types of foods have fiber, and why fiber is key for supporting our health.

What is fiber?

Dietary fiber is a type of carbohydrate that comes from plants, and mostly passes through our digestive system without being broken down. This means that we don’t receive energy in the form of calories from fiber, as we do with carbohydrates, fats and proteins

 

What is the difference between soluble and insoluble fiber?

There are 2 types of fiber — soluble and insoluble. Many plant foods contain a mixture of both. 

Soluble fiber dissolves in water, and forms a gel-like substance in our intestines that helps reduce blood cholesterol and blood sugar. This gel-like substance also helps to slow digestion, which is a good thing because it means we feel full for longer. 

Insoluble fiber provides bulk to the stool and helps food pass more quickly through the stomach and intestines, making it easier to pass a bowel movement. 

In general, we find soluble fiber in legumes, oats, barley, some fruits and some vegetables. We find insoluble fiber in whole-grain products, wheat and corn bran, nuts, seeds and some vegetables and fruits.

 

Does fiber cancel out carbs? 

No. There is a lot of confusion around this topic, and understandably so! Some low carb diets use the concept of “net carbs,” which means taking total carbohydrate amount and subtracting any grams of fiber or sugar alcohols from the total to get a “net carb” number. 

The rationale behind this is that our bodies do not fully digest fiber or sugar alcohols in that our bodies don’t receive calories (or at least not as many as is the case with other types of carbohydrates) from them. The presence of fiber may slow the absorption of other types of carbohydrates in the food you are eating, but it does not cancel those carbohydrates out.

“Net carbs” is not a legal definition and is not recognized by the FDA or the American Diabetes Association. In sum, you’re better off sticking to the total carbohydrates number when looking at nutrition labels.

 

How is dietary fiber beneficial for my health?

How is it NOT is the real question! Some of the properties of fiber that we have discussed contribute to health in big ways. 

  • Lipid levels and heart health:

    Think of fiber as a kind of scrub brush for our insides. It has the ability to bind with lipids, meaning your body will not absorb them. This is great news for our cholesterol levels (total, HDL, LDL) and triglycerides. Research shows that higher fiber intake is associated with lower risk of death from cardiovascular disease and all cancers [1, 2]. 

  • Blood sugar and risk of diabetes:

    Remember that gel-like substance we talked about that forms when we eat fiber? It basically can “trap” glucose aka sugar, which means you absorb less sugar and hence your blood sugar levels are more stable after eating a high-fiber meal. This is hugely beneficial over time when it comes to our risk for diabetes, but it also helps you feel a more stable level of energy when eating. Think comfortably full for a few hours vs a sugar rush and then crash.

  • Good bacteria in our gut:

    Some fibers can be fermented by bacteria in our intestines. This is great for keeping the gut microbiome balanced and happy (p.s. we talk a lot more about this in our group program!) 

  • Colorectal cancer:

    Research has shown correlations between higher fiber intake via whole grains and reduced risk of colorectal cancer [3].

bowls of oatmeal, berries and kiwi on white countertop

What type of foods have fiber?

Fiber comes from plant foods, meaning that fruits, vegetables, whole grains, legumes, nuts and seeds are all good sources of fiber. 

 

Does chicken have fiber?

No, chicken does not have fiber since it is animal meat, not plant-based.

 

Does coffee have fiber?

Coffee does not have fiber, though it can rev the digestive system in the morning. Some research has shown that caffeine can stimulate the urge to poop because it activates muscles in our colon (i.e., large intestine) [4]. 

If you are adding milk or cream, this contains lactose which may also stimulate the urge to go to the bathroom. If you are sensitive to lactose or lactose-intolerant, you may find this especially true for you (we have an am I lactose-intolerant quiz you can take!). There may also be interactions between coffee and certain hormones that stimulate the digestive system. 

coffee cup sitting on table in sun

Do fiber one bars make you poop?

Given that a Fiber One bar has on average about 9 grams of fiber, that can certainly get things moving! For reference, 9 grams of fiber is about ⅓ of an average person’s fiber needs in a given day. 

 

Does fish have fiber?

No, fish does not have fiber. Similar to chicken, fish is an animal protein and thus will not have fiber.

Can you eat too much fiber?

Yes, you can eat too much fiber. Too much fiber can cause a whole variety of uncomfortable gastrointestinal symptoms – constipation, abdominal pain, flatulence, bloating, loose stools. Not fun. 

Most people are not getting enough fiber. When increasing fiber in the diet, it is very important to do so gradually to avoid uncomfortable gastrointestinal symptoms. Making sure you are drinking plenty of water is key too as this helps our bodies handle the fiber.

 

I hope this article was helpful in clearing up some FAQs about fiber! If we missed anything that you’ve been wondering about in regards to fiber, please leave us a comment and we will get back to you!

 

Photo credit:

Photo by Iñigo De la Maza on Unsplash

Photo by Melissa Belanger on Unsplash

Photo by Emre on Unsplash

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About the Author: Kelly Wagner, MS, RD, LDN

I'm a Registered Dietitian (RD) based in Chicago, IL. I have worked in both inpatient and outpatient settings, including dialysis, ICU, as well as one-on-one nutrition counseling and groups.

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    • Kelly Wagner, MS, RD, LDN August 31, 2022 at 10:07 pm - Reply

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