The Truth About Fueling for Runners with Stevie Lyn Smith

Stevie Lyn Smith is a registered dietitian, board certified in sports nutrition, endurance athlete, and one of the most trusted voices when it comes to practical, realistic fueling advice for runners.

As a Board Certified Specialist in Sports Dietetics, Stevie combines her passion for endurance athletics with evidence-based nutrition practices to help individuals reach their health and performance goals. She’s also an ultra-endurance athlete herself, with 10 Ironman finishes, which gives her a firsthand understanding of how nutrition impacts both performance and everyday life. When she’s not training, she’s usually outside exploring trails with her dog or experimenting in the kitchen.

In this episode, Stevie breaks down what fueling actually looks like for everyday runners, not just elites, and why so many people are unintentionally underfueling their training. The conversation covers carbohydrates, hydration, sodium, and protein, with a focus on what’s realistic to execute in both training and racing.

They also get into how fueling impacts recovery, energy levels, and long-term performance, especially for runners balancing training with work, family, and everything else in life. This isn’t about chasing perfect numbers. It’s about understanding your needs, being consistent, and making fueling something that supports your training instead of holding it back.

Jon and Stevie talk about:
• what “high carb fueling” actually means and why it’s individualized
• how to think about fueling for long runs, races, and everyday training
• why most runners are underfueling their weekly training volume
• how carbs support performance, recovery, and adaptation
• hydration, sodium needs, and how to know if you’re a heavy sweater
• fueling for longer efforts like marathons and ultras
• when and why to incorporate protein into long efforts
• balancing carbs and protein without overcorrecting
• how to identify misleading nutrition advice online
• why practical, consistent fueling matters more than perfect plans

Stay connected:

Follow Stevie on Instagram: https://www.instagram.com/stevielynlyn/

Listen to Real Fuel Podcast hosted by Stevie Smith: https://podcasts.apple.com/us/podcast/real-fuel-with-sls/id1746341651

Stevie's website: https://stevielynrd.com

This episode is supported by:

Precision Fuel & Hydration - Dial your fueling in this year. Use code “LONGRUN26” for 15% off your first order at www.precisionhydration.com.

Mount to Coast - Built for runners who go long. From Badwater to Boston, Mount to Coast is designing footwear for the demands of real endurance. Learn more at mounttocoast.com.

Don't miss out on a live podcast recording in Boston at the Marathon Sports Brand House brings together Jonathan Levitt and Joe Corcionefor a candid conversation on training, strategy, and gear for runners looking to take on longer distances from their first 50K to ultramarathons. Sign up here!

Boulderthon - Our favorite Colorado race event with a variety of distances. Use code FTLR2026 for $20 off the marathon or half marathon when you register at www.boulderthon.org.

Good Ranchers - Better training starts with better inputs. Good Ranchers delivers high-quality, American-sourced meat and seafood so you can stay consistent with your protein and iron. Visit goodranchers.com and use code IRON for $25 off plus a free protein each month.

Vacation Races - Run where you play and chase the extraordinary. Use code “FTLR” for 15% off their half marathons, ultras, and trail fests at vacationraces.com through the end of 2026.