Everything You Want to Know About Fiber, but Were Too Scared to Ask

By Kristin Neusel, MS, RD, LD, CDCES

These statements are entirely thoughts of the author and not claims made by the company. The Author was compensated to create this article.

Real talk- fiber has a branding problem. When most millennials hear “fiber”, we think of bland cereals our grandparents used to eat along with foods that would help them with their digestion problems. But fiber is having a major comeback, and for a very good reason! It’s one of the most powerful, underutilized, underloved tools for so many health-related aspects like blood sugar control, metabolism, and gut health to name a few.

The surprise? Most people aren’t getting nearly enough- some not even half of what they should be getting! As a Registered Dietitian, I’m going to break down everything you actually want to know about fiber- without the awkwardness!

What Even is Fiber?

This surprises a lot of people, but fiber is actually a type of carbohydrate! It works differently than other carbs in that your body can’t fully digest it. Unlike other carbs that get broken down into glucose, fiber passes through your digestive system partially or completely intact. To break it down even more, there’s a few different types of fiber (sadly these aren’t always delineated on nutrition labels), but here’s the simplified version:

Soluble fiber dissolves in water and forms a gel. That gel helps slow digestion, stabilize blood sugar, and lower cholesterol among other things. I like to advise people to remember soluble slows things down (S/S!).
Resistant starch is a special type of fiber that “resists” digestion in the small intestine and instead feeds your gut bacteria. It has properties of both soluble and insoluble fibers.

All of these fibers play different roles, and it’s best to have a mix of them for optimal health.

Why Millennials Should Care

If you are in your 20s, 30s, or 40s, fiber might not feel urgent (or maybe, it does!). This is actually the time it can matter most, though, because this is when metabolic health is either built or slowly declines. Blood sugar regulation, gut health, and inflammation all start to shift during these years, especially with high stress, travel, eating out, and busy schedules. Most millennials are averaging around 10 to 15 grams of fiber per day. The recommendation is closer to 25 to 38 grams (1,2). That gap may seem small, but it matters more than people may think.

What Happens if You Don't Get Enough Fiber?

More real talk about consequences for not getting enough fiber? Let’s get into it…

Blood sugar spikes and crashes: Without enough fiber, carbohydrates are digested more quickly. This can lead to sharper spikes in blood sugar followed by energy crashes, cravings, and that “hangry” feeling a few hours later (3).
Poor gut health: Fiber feeds your gut bacteria. Without it, beneficial bacteria struggle to thrive, which can impact digestion, immunity, and even mood (4).
Constipation or irregular digestion: Low fiber intake is one of the most common causes of constipation, bloating, and inconsistent bowel movements (5).
Increased hunger: Fiber helps you feel full and satisfied. Without it, meals tend to be less filling, which can lead to overeating or constant snacking (6).
Long term health risks: Low-fiber intake is associated with higher risk of heart disease, type 2 diabetes, and certain cancers, especially colorectal cancer (7).

Why Does Fiber Feel so Confusing?

The biggest confusion I see from people is the fact that there’s many different kinds of fibers, and that can get confusing. You’re told to eat fiber if you’re constipated and have diarrhea, so off the bat that can create confusion- that’s where you need to dig deeper and get into types of fiber.

Then gut health in general is really confusing. Terms like “net carbs”, "prebiotics" or “functional fibers” are mentioned a lot and people wonder what actually matters (and what even are those things!). As mentioned above, not all fibers behave the same. For example, resistant starch acts more like a prebiotic. It feeds beneficial gut bacteria, which then produce short-chain fatty acids like butyrate (we want this, it’s a good thing!). These compounds support gut-lining health, reduce inflammation, and may improve insulin sensitivity (8,9).

So when you hear that some fibers do more than just help digestion, that’s what people are talking about.

Can You Get Too Much Fiber?

Yes, but the bigger issue is usually how quickly you increase it. It’s recommended to increase fiber slowly over time, and also increase your fluid intake as you increase fiber. Be sure to work with your healthcare provider about what’s right for you. Fiber increases require your body and gut to adjust and get used to it. Typically clients who experience some gas after increasing fiber intake will see a decrease in that symptom after adjusting, but again- everyone is different.

Learn more

How Can You Eat More Fiber Without Overhauling Your Life?

This doesn’t have to be complicated! Focus on small, realistic upgrades to your current eating plan. That could look like choosing breads and grains that contain higher amounts of fiber and resistant starch, adding a fiber source to meals you already eat like avocado on toast or beans in a salad, or swapping out refined carbs for options that include functional fibers. Functional fibers are things like Hero Bread baked goods, for example. You’ll want to build meals that combine protein, fat, and fiber to slow digestion and improve satiety.

Where does resistant starch fit in?

Resistant starch is one of the most exciting areas of fiber research right now (okay, yes, I’m a nerd!). Because it’s not fully digested, it doesn’t spike blood sugar the same way traditional starches can. Instead, it travels to the colon where it’s fermented by gut bacteria. This process produces beneficial compounds that support gut health and metabolic function (8,9). As a dietitian, I look at fiber quality just as much as fiber quantity. The type of fiber and how it functions in the body can make a meaningful difference.

So . . . Do You Need to Overthink This?

Not really. If there is one takeaway, it is this: most people would benefit from simply eating more fiber, more consistently, it’s really that simple.

TL;DR? Fiber is not just about digestion. It plays a major role in blood sugar control, gut health, satiety, and long term disease prevention. Most millennials are not getting enough, and small, consistent changes can make a big impact.

References

Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press; 2005.
USDA. Dietary Guidelines for Americans 2020–2025. U.S. Department of Agriculture and U.S. Department of Health and Human Services.
Jenkins DJ, Kendall CW, Axelsen M, Augustin LS, Vuksan V. Viscous and nonviscous fibers, nonabsorbable and low glycemic index carbohydrates, blood lipids and coronary heart disease. Curr Opin Lipidol. 2000;11(1):49–56.
Makki K, Deehan EC, Walter J, Bäckhed F. The impact of dietary fiber on gut microbiota in host health and disease. Cell Host Microbe. 2018;23(6):705–715.
Slavin JL. Dietary fiber and body weight. Nutrition. 2005;21(3):411–418.
Clark MJ, Slavin JL. The effect of fiber on satiety and food intake: a systematic review. J Am Coll Nutr. 2013;32(3):200–211.
Reynolds A, Mann J, Cummings J, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019;393(10170):434–445.
Birt DF, Boylston T, Hendrich S, et al. Resistant starch: Promise for improving human health. Adv Nutr. 2013;4(6):587–601.
Sajilata MG, Singhal RS, Kulkarni PR. Resistant starch–a review. Compr Rev Food Sci Food Saf. 2006;5(1):1–17.

*All figures listed are per serving. Not a low calorie food. Some products contain allulose. See nutrition facts on each product page.