Carbs For Exercise? Let’s Challenge This Idea

For decades, athletes and everyday individuals alike have been told the same story: carbohydrates are king. From locker rooms to clinical guidelines, high carb fueling has been positioned as essential for performance and metabolic health. But what if that narrative is incomplete, or even misguided?

On this episode of The Empowering Neurologist, I sit down with Dr. Andrew Koutnik to explore a groundbreaking new paper published in Endocrine Reviews that challenges more than a century of conventional thinking about sports nutrition and human performance.

Dr. Koutnik is uniquely qualified to lead this discussion. As a metabolic scientist and researcher who has devoted his career to understanding fuel utilization, mitochondrial function, and metabolic flexibility, he brings both intellectual rigor and personal experience to the conversation. His work synthesizes nearly 600 studies and reframes the long-held assumption that high carbohydrate intake is required for optimal athletic output. Instead, the data suggest that chronic high-carb fueling may suppress fat oxidation, impair metabolic flexibility, and even elevate long-term metabolic risk, even in athletes.

If this sounds familiar, it should. In Grain Brain, published in 2013, I discussed how excessive carbohydrate consumption drives insulin resistance, inflammation, and metabolic dysfunction. What Dr. Koutnik’s work does is extend that conversation into the realm of athletic performance, showing that metabolic health and performance are not mutually exclusive. In fact, they are deeply intertwined.

We’ll unpack why traditional recommendations of 5–12 grams of carbohydrate per kilogram per day—and 60–120 grams per hour during exercise—may not only be unnecessary for many individuals, but potentially counterproductive. More importantly, we’ll discuss what metabolic flexibility truly means, and why the ability to efficiently oxidize fat may be one of the most powerful markers of resilience—both in the brain and in skeletal muscle.

In this episode, we will also explore another compelling topic: the efficacy and safety of long-term ketogenic diet therapy in a patient with type 1 diabetes. This case challenges deeply ingrained fears surrounding nutritional ketosis in this population and opens a critical discussion about individualized, data-driven care.

This conversation is about clarity in a field that has become polarized and confusing. It’s about moving beyond dogma and asking a better question: What fuel strategy best supports long-term metabolic health, mitochondrial efficiency, and human performance?

If you care about brain health, metabolic resilience, and the future of nutrition science, you won’t want to miss this episode.

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Dr. Andrew Koutnik is a research scientist whose career bridges cutting-edge science, elite performance, and personal experience living with type 1 diabetes for over 17 years. His work focuses on how nutrition, metabolism, and lifestyle can be leveraged to maximize human health, performance, and resilience across diverse conditions—from chronic disease to extreme environments.

Dr. Koutnik earned his Ph.D. in Medical Sciences (Molecular Pharmacology and Physiology) from the University of South Florida Morsani College of Medicine. Prior to joining FSU, Dr. Koutnik served as a Faculty/Principal Investigator at Sansum Diabetes Research Institute and Florida Institute for Human and Machine Cognition. His research has spanned over $70,000,000 in research funding, including NASA missions, U.S. Special Operations Command, Defense Advanced Research Projects, Office of Naval Research, Department of Defense, and NIH-funded clinical trials, investigating the role of nutrition and metabolism in health, disease, and high-performance contexts resulting in over 100 scientific publications and/or international presentations, including awards/recognition from NASA, Presidential Fellowship, Endocrine Society, Physiological Society, Health Equity Action Network, USF Academy of Inventors, amongst others.

As faculty at Florida State University’s Institute for Sports Science and Medicine, Dr. Koutnik leads and collaborates on projects at the intersection of exercise physiology, cardiometabolic health, and therapeutic nutrition. His ongoing NIH- and DoD-supported studies explore dietary strategies for type 1 and type 2 diabetes, obesity, sleep, and elite performance under metabolic stress. He is also actively involved in international collaborations with Harvard Medical School, Boston Children’s Hospital, University of Washington School of Medicine, University of British Columbia Breakthrough Type 1 Diabetes Center of Excellence, Buck Institute for Research on Aging, amongst others.

At the core of his mission is a commitment to maximizing metabolic health and performance—advancing evidence-based nutrition and lifestyle strategies, and empowering individuals to thrive in the face of chronic disease and extreme demands, including elite performers.

Dr. Koutnik has returned home to Tallahassee and Florida State University, where he lives with his wife Kelly, their two energetic sons, and their beloved pets—Cocoa (dog) and Professor Peaches (cat). Outside the lab, he finds joy in training Brazilian Jiu Jitsu and staying active through both strength and endurance exercise.

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