Some Work, All Play – Episode 295

Debunking Low Carb Science for Endurance Athletes
Hosts: David Roche & Megan Roche
Date: January 27, 2026

Overview

In this emotionally nuanced and science-packed episode, David and Megan Roche tackle the recent social media uproar surrounding a narrative review promoting low-carb strategies for endurance athletes. The hosts dig deep into the claims behind low-carb science, dissect the flaws in recent studies, and emphasize what decades of real-world data and physiological understanding tell us about high-carb fueling for performance and health—particularly for female athletes. In between, they share personal stories, uplifting listener messages, and reflections on the role of compassion and nuance both in sport and life. The episode also covers the topic of bone density and stress fractures, highlights a moving interview with athlete Beth McKenzie, and provides a quick hit of science on recent relevant studies.

Episode Structure & Key Segments

• [00:00] – [02:45] A somber opening and heartfelt commentary on recent events
• [03:02] – [10:00] Pizza, cheese, and why energy availability matters
• [10:00] – [14:39] Cycling breakthroughs and the value of cross-training
• [15:44] – [17:37] Bicarbonate ("bicarb") for performance & fueling sponsorships
• [17:37] – [53:38] Debunking low-carb science & the narrative review deep dive
• [54:05] – [63:41] Listener spotlight: Beth McKenzie and the complexities of anti-doping in sport
• [64:03] – [66:58] Quick takes: Alex Honnold, climbing, and the physiology of fear and stamina
• [67:08] – [84:53] Science quick-hitter: Bone density, stress fractures, and life advice
• [80:19] – [85:24] Listener celebration and closing moments

Detailed Breakdown & Key Insights

1. Emotional and Political Context [00:00–02:45]

• David & Megan open with a somber tone, reflecting on tragic events in Minnesota and the responsibility to acknowledge truth and lead with compassion.
• They honor the memory of Alex Preddy, reading a powerful statement from his family and emphasizing their commitment to honesty and inclusion, regardless of differences among listeners.

"We want this podcast to be for everyone. You can disagree with us politically and we love you…" – David, [00:30]

2. Carbs, Pizza, And Energy Availability [03:02–05:16]

• David and Megan riff humorously about their love for extra cheese pizza and how energy availability directly impacts training and recovery—using pizza as an accessible entry into the fueling discussion.
• Performance tip: Under-fueling (whether by insufficient carbs or cheese!) leads to poor recovery and training adaptation.

"This is a way to talk about fueling and the importance of treating your body well is sometimes you gotta go double extra cheese." – David, [04:54]

"Double extra cheese is performance cheese." – Megan, [05:02]

3. Cross-Training Successes [06:00–14:39]

• Megan shares her breakthrough uphill treadmill workout after rest for a micro-injury—crediting both rest and vigorous cross-training (Zwift cycling) for her improvement.
• Importance of zone 2 (Z2) training and cycling as supplemental aerobic development.
• Key insight: Cross-training (primarily cycling) is increasingly important for runners in 2026, shifting the focus away from total run mileage as the primary metric.
• Physiological lesson: Higher cadence cycling is translating to improved running performance.

"2026 is the year of cross training from a training theory perspective… mileage matters, but it's not actually the thing that's driving adaptations." – David, [09:20]

4. Bicarbonate Supplementation [15:44–16:52]

• Megan reads a listener testimonial on the performance-boosting effects of bicarbonate before a 10k race.
• Practical tip: Start with lower doses; integrate with carb-rich fueling for best results.
• Humorous aside about the DIY approach to using Morton bicarb solutions.

5. Debunking Low-Carb Science (Main Discussion) [17:37–53:38]

A. Why This Matters (and Potential Harm)

• Low-carb messaging is pervasive and can be harmful, especially for those with disordered eating tendencies or for female athletes.
• Real-world data and performance trends in endurance sports overwhelmingly support high-carb strategies.

"We don't want to be talking about low-carb science. It's just not necessarily important… But when the message is shouted from the rooftops… we're like, all right, we should counter this." – David, [17:52]

B. The Problem with the Research Cited

• The main study under review is a 2025 trial with 10 male triathletes, testing four conditions (varying carb intakes, often as low as 10g/hour) at only 70% VO2 max.
• Key criticisms:
  • Minimal carbohydrate dosing in the study does not reflect real-world best practice.
  • Low intensity and lack of female subjects limit relevance.
  • Results cherry-picked and interpretations biased.
• Megan highlights that even small carb amounts improve performance—but these studies don't test nor consider modern higher carb intakes (60–120g/hour) now common in elite racing.

"What happens when you start thinking about higher total numbers, like 60, 90, 120… That's a much more interesting question." – Megan, [28:20]

C. The Narrative Review—Bias and Flawed Interpretation

• The new "narrative review" cited by low-carb advocates leans on over 600 citations but is heavily influenced by a priori bias and questionable use of AI in literature synthesis.
• Discussion of "small glucose pool" (blood glucose) versus "large glucose pool" (muscle glycogen).
• Flawed central argument: Only maintaining blood glucose is necessary, so endurance athletes should only ingest ~10g carbs/hour.
• The hosts systematically dismantle these claims:
  • Dose-response evidence is ignored or dismissed despite real-world and published results to the contrary.
  • The review is accused of dressing opinion as science by filtering data through a pre-formed narrative, rather than unbiased inquiry.

"There is zero chance that these authors were ever going to come to a different conclusion. And my question is, is that science or is that an opinion piece?" – David, [23:49]

• Notable Quote:

  "Everyone is welcome to their opinions… but if those opinions are not backed up with real world practice, a scientific article can read more like a fantasy novel." – Megan, [51:30]

D. Real-world Data and Training Theory

• The actual practice in elite endurance sport (cycling, running, etc.) is very high carbohydrate consumption, shown to drive both performance and health.
• Female athletes are particularly at risk for negative health effects with low-carb/fat-adapted approaches; endocrinological consequences are well-documented.
• Nuance: More carbs isn’t always better in every context, but high-carb fueling is necessary for high output and robust health in endurance sport.

"We love carbs because we love performance, but mostly we love carbs because we love people." – David, [51:15]

• Memorable Metaphor:

  "If zero is not very good and 10 grams is 22% improvement, we're like, well, 90 grams is obviously gonna be way more." – David, [28:28]

6. Listener Story: Beth McKenzie and The Complexity of Anti-Doping [54:05–63:41]

• Beth, an accomplished athlete and coach, was wrongfully sanctioned due to supplement contamination and strict liability anti-doping rules. Megan and David recount Beth's resilience, compassion, and ongoing inspiration within the sport.
• Key issues:
  • The system often fails to account for nuance or intent.
  • Trail racing's casual fueling (unknown origin of aid-station food/drink) collides problematically with rigorous liability standards.
• Beth's story is both cautionary and uplifting, emphasizing community and compassion over dogma and rigid enforcement.

"All systems need space for compassion and nuance…" – David, [61:02]

7. Pop Culture & Physiology: Alex Honnold's Skyscraper Climb [64:03–66:58]

• Megan describes watching Alex Honnold’s Taipei 101 climb with "palms sweating" and reflects on the physiology of fear and endurance.
• David muses about the risk calculus professional climbers make, their ability to compartmentalize, and whether supplemental strategies (like bicarb) could apply.
• Some fun banter about Tool (the band), climbing, and driving in the snow with their kids.

8. Science Quick-Hitter: Bone Density and Stress Fracture Risk [67:08–77:57]

• Summary of a recent Japanese prospective study on elite female runners (21 athletes, monitored for six months; high incidence of stress fractures).
• Key findings:
  • DEXA-measured lumbar spine bone mineral density is the strongest predictor of stress fracture risk.
  • Takeaway for listeners: All who have a history of disordered eating, amenorrhea, or repeated bone injuries should get a DEXA; low bone density is not destiny.
• Listener Q&A: A young woman with low BMD and frequent injuries asked if she must give up running. Megan and David provide a deeply compassionate, science-based view—she should not lose hope, as recovery and bone health can significantly improve even after years of difficulty.
• Practical tips: More carbs, regular periods, strength training (especially load-bearing), high-dose vitamin D (if deficient), and possibly collagen for tendons.

"Every single one of them is able to work through it eventually … the body is miraculous. It is so wild what you can see when days add up to weeks, up to years." – David, [74:13]

9. Listener Corner & Episode Wrap [80:19–85:24]

• The episode finishes with a celebration of a longtime listener earning a PhD while the podcast kept them company.
• Joyful banter about hair, nails, collagen, family, and the emotional support system sports provide through difficult times.
• The hosts share their gratitude and wish for more simple, fun episodes—but affirm the value in deep dives, even if the science feels contrarian or complex.

"We love you. Thanks for being here. If you want a simple episode, talk about Patreon. That's a place where last week we had the goofiest episode of all time." – David, [83:07]

Notable Quotes & Moments

• "Double extra cheese is performance cheese." (Megan, [05:02])
• "Carbs seem to address all of these questions… but nothing in human physiology is simple, especially metabolism." (David, [49:10])
• "There is a boneyard of ruined careers from serious endurance athletes who have undershot carb intake." (David, [51:10])
• "If those opinions are not backed up with real world practice, a scientific article can read more like a fantasy novel. And unfortunately… without wizard fucking." (Megan, [51:30])
• "All systems need space for compassion and nuance, and I think that that's really important." (David, [61:02])
• "Every single one of them is able to work through it eventually… the body is miraculous." (David, [74:13])

Timestamps for Key Discussion Points

• [00:00] – Somber intro, political and social context
• [04:41] – Pizza, cheese, energy availability and performance
• [06:22] – Megan's cycling and training breakthroughs
• [15:44] – Bicarbonate supplementation testimonial
• [17:37] – Why debunking low-carb claims matters
• [23:50] – Is biased science still science?
• [28:20] – Dose-dependency of carbohydrate intake
• [51:15] – Performance versus health: why carbs matter most
• [54:05] – Beth McKenzie's anti-doping story
• [64:03] – Alex Honnold's Taipei 101 climb and physiology
• [67:08] – Bone density, stress fractures, and athlete advice
• [80:19] – Listener celebration (PhD defense story) & closing feelings

Tone and Takeaways

• The episode is equal parts rigorous, heartfelt, and irreverent—reflecting the Roches' scientific expertise, commitment to inclusivity and mental health, and signature playful banter.
• Listener takeaway:
  • Don’t be swayed by flashy headlines or narrative reviews detached from real-world practice. The best science matches what decades of athletes and coaches have learned through competition and care.
  • High-carb fueling remains foundational for performance and health.
  • Compassion and community matter more than dogma, in sport and in life.

For more:

• Listen to bonus content and get training plans on Patreon ([53:33])
• Support athlete Beth McKenzie via Wynn Republic
• Reach out with science questions and for support—this community has your back!