Exogenous Ketones: Practical Guidance for Endurance Athletes
Insights and protocols from Dr. Dan Plews
Introduction
In Ironman racing, few topics spark as much debate as exogenous ketones. Some athletes swear by them, while others dismiss them as overpriced gimmicks. Dr. Dan Plews, an elite age-group world record holder and exercise physiologist, offers a balanced perspective: "Ketones won't transform a mid-packer into a podium finisher, but used wisely, they can help you train harder, recover better, and stay sharper late in a race."
Let's explore what the science says about exogenous ketones, when they work, when they don't, and how you can use them strategically for performance and recovery.
Understanding Ketone Types: Not All Are Created Equal
Before diving into protocols and benefits, it's crucial to understand that not all exogenous ketones are the same. The three main types vary dramatically in effectiveness, cost, and practical application:
Ketone Salts
These combine beta-hydroxybutyrate (BHB) with minerals like sodium, magnesium, or calcium. They're affordable and widely available but less effective at raising blood ketone levels. Dr. Plews notes, "You have to take quite a lot to see any effect, which means you're also ingesting a large dose of salts," which can lead to GI discomfort.
Ketone Esters
Currently the gold standard, esters are potent and well-studied. They raise blood BHB levels quickly, making them the preferred choice for research and elite performance. However, they taste notoriously bad and are expensive.
Ketone Precursors
These molecules, like 1,3-butanediol, convert into ketones in the body. They're less potent than esters but may be easier to tolerate. However, some athletes experience mild intoxication or GI distress.
Key Takeaway: For serious performance and recovery applications, ketone esters have the strongest scientific support and most reliable effects.
Race-Day Performance: Separating Hype from Reality
The performance-enhancing claims around ketones generate excitement and skepticism. Dr. Plews' personal racing experience provides valuable real-world context.
The Mixed Evidence on Performance
Research suggests that ketones are unlikely to help high-intensity efforts lasting 60 minutes or less. However, they may offer marginal benefits in longer, steady-state efforts typical in Ironman racing.
Dr. Plews' Racing Protocols
In his record-setting races, Dr. Plews used a combination of carbohydrates and ketones. For example, during Ironman California 2022, he used 32 grams of ketone esters distributed over the bike leg, combined with medium-chain triglycerides (MCTs) and electrolytes.
Practical Racing Protocol
For athletes considering ketones in competition, Dr. Plews recommends starting with 0.25 to 0.29 grams of ketones per kilogram of body weight, combined with carbohydrates, MCTs, and electrolytes.
The Mental Performance Edge
Research shows that ketones can improve focus and reduce perceived effort during long efforts. Dr. Plews emphasizes this mental sharpness as a valuable benefit for long-course athletes.
Key Takeaway: Don't expect dramatic physical performance gains from ketones on race day. However, for ultra-endurance events, the mental clarity and reduced perceived effort may justify their strategic use.
The Stronger Case: Recovery and Training Adaptation
While performance benefits are modest, ketones offer compelling recovery and training adaptation benefits. Dr. Plews continues using ketones for these purposes.
Real-World Recovery Evidence
Dr. Plews' experience at a recent HYROX competition illustrates ketones' recovery potential: "I competed in two HYROX competitions back-to-back—one in the evening, and the other the next morning. I took ketones in between, and it felt genuinely game-changing."
Physiological Mechanisms for Recovery
- Angiogenesis stimulation: promotes new blood vessel formation.
- Natural EPO boost: elevates erythropoietin levels, enhancing oxygen-carrying capacity.
- Improved sleep quality: enhances sleep efficiency and counteracts REM sleep decline.
- Enhanced training sustainability: blunts overreaching symptoms during intense training.
Strategic Implementation for Recovery
Given the cost of ketone esters, Dr. Plews recommends strategic timing during peak training blocks and between consecutive hard sessions.
Key Takeaway: The recovery and adaptation benefits of ketones may be more valuable than their direct performance effects, particularly for competitive athletes.
Practical Implementation Guide
Dosing Protocols
- Starting dose: 0.25-0.29 g per kg body weight
- Target blood BHB: 1-2 mmol/L (if monitoring)
- Distribution: spread intake over 2-4 hours
Timing Strategies
- Race day: throughout bike leg for long-course events
- Recovery focus: post-training and/or before bed
- Training blocks: daily during peak stress periods
Budget Optimization
- Strategic periodization: use during key training blocks
- Focus on recovery: prioritize post-training applications
- Quality over quantity: invest in ketone esters
Integration with Existing Nutrition
- Combine with carbohydrates: don't replace primary fuel sources
- Add MCTs: 1 tablespoon helps stabilize ketone levels
- Include electrolytes: buffer potential acidosis with quality electrolyte supplements
- Maintain hydration: support optimal ketone metabolism
Safety and Considerations
Potential Side Effects
- GI distress: particularly with higher doses
- Mild acidosis: monitor hydration
- Individual variability: response varies
Testing Protocol
- Start in training: never test new protocols on race day
- Begin conservatively: use lower doses initially
- Monitor response: track subjective feel and objective measures with a GPS running watch
- Adjust gradually: optimize dose and timing
The Bottom Line: Strategic Application Over Hype
Dr. Plews' perspective on exogenous ketones reflects the nuanced reality of modern sports nutrition: they're neither miraculous performance enhancers nor worthless marketing gimmicks. Instead, they're a tool that, when applied strategically, can provide meaningful benefits in specific contexts.
For most athletes, the recovery and adaptation benefits likely outweigh the modest race-day performance gains. The mental clarity and focus benefits during ultra-endurance events, combined with enhanced recovery between hard sessions, may justify the investment for serious competitive athletes.
However, ketones should supplement, not replace, fundamental performance drivers: consistent training, adequate sleep, proper nutrition, and smart recovery practices. They're an optimization tool for athletes already executing the basics well, not a shortcut to performance gains.
Action Steps for Implementation
- Start with recovery applications: test ketones post-training before considering race-day use.
- Choose quality products: invest in ketone esters for reliable, research-backed effects.
- Test thoroughly: establish individual protocols during training before competition.
- Time strategically: use during peak training blocks when recovery matters most.
- Monitor response: track subjective feel and objective measures where possible.
As research continues to evolve our understanding of exogenous ketones, one thing remains clear: they're not magic, but for the right athlete in the right context, they can provide a meaningful edge in the margins where competitive advantage is won.
