Protein, Carbohydrate, and Fat — Is There a Fourth Macronutrient? (Yes, It’s Called Fiber)

Carbohydrate. Fat. Protein. Contrary to popular belief, these are not the only three macronutrients you should care about. There's also fiber.

Organic avocado with seed, avocado halves and whole fruits on yellow and green background

Carbohydrate gives you the energy to push hard in the gym. Protein helps repair those torn muscles so they grow bigger and stronger. Fat builds hormones — which, yes, includes anabolic ones like testosterone.

That’s it; these are the only three macronutrients worthy of your attention, right? Wrong.

You're forgetting a fourth: fiber. (Note: there are 7 macronutrients in total, including water, but we’ll save those for another article.)

Wait … fiber? The tough bits in roasted asparagus and brussels sprouts you're always almost choking on? That’s something you need to care about, too? *Cue shocked face* Uh-huh. You bet. Continue reading to find out why.

Yes, fiber is a macronutrient

To understand why, let's pull up the definition of "macronutrient" from the United States Department of Agriculture (USDA) real quick:

Macronutrients are types of foods that are needed in large quantities in the diet.

Just as there’s “up” to “down” and “high” to “low”, there’s “micronutrients” to “macronutrients”.

So, for a complete picture, micronutrients are vitamins and minerals your body needs in tiny amounts. As a general rule of thumb, we're talking milligrams or micrograms.

And since the recommended daily intake of fiber is between 30-35 grams daily for men and 25-32 grams daily for women, it’s safe to say this particular nutrient falls in the “macro” side of things.

What does fiber do?

OK. So, fiber is a macronutrient. But, honestly, so what?

Well, if your understanding of fiber ends at “it helps you stay regular in the bathroom” — and (skip this if you hate puns) you couldn’t give two shits about it — this section is for you. Below, you’ll learn why fiber deserves a spot on your plate.

But before that, let’s clear something up. Not all fiber:

🧛 Suck moisture from your mouth like a newly-turned vampire feasting on an unsuspecting victim,

🫣 Lodge itself into the worst possible spaces between your teeth (think: spinach in your 2 front teeth on a first date),

🙅 Form an unchewable and un-get-down-able ball of fibrous-y mess you have no choice but to spit out (pro-tip: drink something)

Meet the 2 types of fiber: insoluble fiber and soluble fiber

Everything above describes insoluble fiber; one of the two fiber types. Here’s what you need to know:

  • Soluble fiber: Um, well, this dissolves in water. Includes plant pectin and gums.
  • Insoluble fiber: Doesn’t dissolve in water. *cough* you’ve found your culprit *cough* Includes plant cellulose and hemicellulose.

Still, we wouldn’t recommend that you avoid insoluble fiber for 2 reasons.

First, it's close to impossible — most foods contain a mix of soluble and insoluble fiber. And second, as much as you couldn't give 💩 💩 (get it???) about it, maintaining regular bowel movements prevent hemorrhoids and lower your risk of colon cancer.

So, despite all the grief they cause you, insoluble fiber is still a must-have in your diet.

What about soluble fiber? Get ready to be impressed; soluble fiber could help:

But how will all that help you with your fitness goals?

Hmm. But there’s nothing about better athletic performance? Or enhanced muscle growth?

Only outrightly … see, if you read between the lines, fiber essentially promotes optimal health. And when you’re feeling your best, it’s only natural that you’d be able to do your best in the gym, around the track, or on the mat, too.

Plus, if you’re trying to lose weight, consider fiber your BFF.

It adds bulk to your food without the calories, helping you stay full for longer between meals. Remember: fiber = your secret weight loss tool.

Psst, here are more foods that’ll help you eat less without starving:

How to Eat Less without Starving Yourself
Creating a calorie deficit isn’t about eating less food. It’s really more about making smarter nutritional choices. Find out why in this article.

Where to get all that fiber goodness

Convinced? Good. And now, time for the million-dollar question. Where can you get yourself all that fibrous-y goodness? Here: whole grains, vegetables, fruits, legumes, and beans.

To help you get a quick start on your fiber journey, here are 10 foods jam-packed with fiber:

  1. Pinto beans
  2. Edamame
  3. Acorn squash
  4. Broccoli
  5. Bananas
  6. Cauliflower
  7. Brussels sprouts (mm-hmm)
  8. Artichokes
  9. Raspberries
  10. Avocadoes

Warning: don’t get overly enthusiastic

More is not always … more. But how much fiber is too much?

While there are no official numbers, it’s pretty obvious when you go overboard on the fiber intake. That’s because you’ll start to run into some uncomfortable and pretty nasty symptoms, like:

  • Bloating
  • Abdominal pain
  • Flatulence
  • Loose stools or diarrhea
  • Constipation
  • Intestinal blockage (commonly seen in people with Crohn’s disease)

Oh, and here are 2 tips. Gradually increase your fiber to the recommended daily intake — so your digestive system has enough time to adapt. Also, instead of stuffing all your fiber-rich foods within one meal, spread them out throughout the day.

Woah, your list is getting long

On the nutrition front, you need to account for:

And on the workout front, there’s:

It’s a lot. And now, adding to all that, is a fourth macronutrient? If you’re feeling overwhelmed, that’s understandable.

But what if we told you we could take nutrition tracking + training programming and logging off your plate?

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Anderson, J. W., Baird, P., Davis, R. H., Ferreri, S., Knudtson, M., Koraym, A., Waters, V., & Williams, C. L. (2009). Health benefits of dietary fiber. Nutrition Reviews, 67(4), 188–205.

Barber, T. M., Kabisch, S., Pfeiffer, A. F. H., & Weickert, M. O. (2020). The Health Benefits of Dietary Fibre. Nutrients, 12(10), 3209.

Macronutrients | National Agricultural Library. (n.d.). Retrieved February 1, 2023, from

Stephen, A. M., Champ, M. M.-J., Cloran, S. J., Fleith, M., van Lieshout, L., Mejborn, H., & Burley, V. J. (2017). Dietary fibre in Europe: Current state of knowledge on definitions, sources, recommendations, intakes and relationships to health. Nutrition Research Reviews, 30(2), 149–190.