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Fibermaxxing: The Science of Healing Your Gut with Dr. Will Bulsiewicz

Mar 12, 2026

Dr. Will Bulsiewicz, board-certified gastroenterologist and bestselling author focused on gut health and the microbiome, shares why fiber is central to a healthy gut. He explains fibermaxxing, how to increase fiber safely, the role of short-chain fatty acids like butyrate, and practical starter foods such as smoothies and soups. The conversation highlights microbial diversity, gut barrier health, and strategies to rebuild your microbiome.

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ADVICE

Increase Fiber Slowly To Avoid Discomfort

Increase fiber gradually to let your gut and microbiome adapt, adding about 3 grams per week until you reach your goal.
Dr. Will Bulsiewicz recommends weekly 3‑gram increments so someone at ~15 g/day can reach 30–40 g without bloating or discomfort.

ADVICE

Use Smoothies And Soups For Gut Rehabilitation

Start fiber reintroduction using pre‑digested plant foods like blended soups and smoothies to rehabilitate a sensitive gut.
Use low‑FODMAP choices early so the microbiome does less work while you rebuild tolerance.

ADVICE

Blend Seeds To Unlock Extra Fiber

Make smoothies high‑fiber by blending whole seeds like chia, flax, and hemp to release soluble fiber locked inside seed shells.
Dr. B says blending actually increases usable fiber because it breaks seed shells and releases prebiotic fiber.

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Fiber may be the single most powerful nutrient for improving gut health — yet most people aren't getting nearly enough of it.

Enter Fibermaxxing.

On this episode of The Exam Room Podcast, Chuck Carroll sits down with gastroenterologist and bestselling author Dr. Will Bulsiewicz to break down the science of how fiber transforms the gut microbiome and why it may be one of the most powerful tools we have for preventing chronic disease.

But this conversation goes far beyond the basics.

Dr. B explains how fiber feeds beneficial gut bacteria, why microbial diversity matters for long-term health, and how the metabolites produced by your microbiome influence inflammation, metabolism, immunity, and even brain function.

You'll also learn why short-chain fatty acids like butyrate are so important for colon health, how the gut barrier protects the body from disease, and what happens when the microbiome is starved of fiber.

Most importantly, Dr. B explains exactly how to start fibermaxxing safely and effectively — including how to increase fiber intake without uncomfortable bloating and which foods are best for rebuilding a healthy microbiome.

Whether you're trying to improve digestion, reduce disease risk, or optimize your microbiome, this episode will give you the science-backed strategies to start today.

In this episode you'll learn:

• What fibermaxxing is and why it's gaining attention • How fiber feeds the gut microbiome • Why microbial diversity is critical for health • The role of short-chain fatty acids like butyrate • How fiber strengthens the gut barrier • Why fiber intake is linked to lower risk of heart disease, cancer, and diabetes • How to increase fiber safely without digestive discomfort • The best foods for rebuilding your microbiome

Dr. Bulsiewicz also shares practical strategies for improving digestion and explains why your gut microbiome may be one of the most important predictors of long-term health.

If you're ready to take your gut health to the next level, this episode is packed with insights you won't want to miss.

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