Fuelin Sessions Challenging the "More Carbs is Better" Dogma with Dr. Alan McCubbin
Oct 16, 2025
Dr. Alan McCubbin, a sports nutrition expert, challenges the notion of 'more carbs is better' for athletes. He discusses how personalized carbohydrate intake can optimize performance, revealing the intricacies of individual oxidation rates and their impact on fueling strategies. The conversation dives into gut training, gastrointestinal symptoms, and the surprising benefits of lower carb intake. Alan also addresses the relationship between power output and oxidation, and offers practical advice for athletes to balance nutrition with performance needs.
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What Exogenous Carbs Really Mean
- Exogenous carbs are those taken during exercise and tracked with stable isotope tracers to see if they reach muscles.
- This distinguishes fuel from endogenous glycogen and reveals absorption and oxidation bottlenecks.
Why They Deliberately Overfed Glucose
- Researchers overfed 90 g/h glucose to reveal true oxidation limits rather than feeding-limited results.
- They then reduced intake to 20% above each person's peak exogenous oxidation to test sufficiency.
Large Individual Variability In Needs
- Personalized intake averaged 65 g/h versus 90 g/h because individuals varied widely in oxidation.
- Some athletes needed as little as ~49 g/h while others oxidized up to ~80 g/h of glucose.