Is getting lighter always the answer for runners chasing faster race times? Matt Fox is joined by Dr David Lipman for a short, sharp discussion about weight loss, performance, RED-S and the risks of taking leanness too far.
Dr David Lipman Links
Instagram: https://www.instagram.com/drdavidlipman/
Website: https://www.drdavidjlipman.com/
Listen to David's Podcast
For more conversations exploring the science, psychology and hidden stories behind sport, check out 1% Better - Hidden Stories in Sport, co-hosted by Xylon van Eyck and Dr David Lipman.
Matt Fox Links
Coaching: https://sweatelitecoaching.com/matt-fox/
Supporters Club: https://sweatelite.co/supporters-club/
Instagram: https://www.instagram.com/mattinglisfox/
Strava: https://www.strava.com/athletes/6248359
Email: matt@sweatelite.co
Matt and David explore why being lighter does not automatically make an athlete faster. Although reducing excess body fat may improve running economy and performance, there is a lower limit where continued weight loss can begin to compromise health, recovery and long-term performance.
Matt shares his own experience of becoming faster after losing weight, while David explains why the human body cannot be treated like a simple machine. Some body fat may provide an important energy buffer because the absorption and use of fuel can vary between athletes and from day to day.
They examine Ryan Hall's experience as a cautionary example. Hall initially improved while becoming extremely lean, but his performance and health eventually declined after taking the process too far. This temporary improvement can create a dangerous "more is better" mindset, where athletes continue restricting food because the early results appear positive.
The conversation also breaks down Relative Energy Deficiency in Sport, commonly known as RED-S. Rather than viewing RED-S as the result of one isolated mistake, David describes it using a stress bucket model. Training load, inadequate fueling, poor sleep, work pressure and other life stressors can accumulate until the athlete's ability to recover is overwhelmed.
Matt and David discuss carbohydrate periodization and carb cycling, including when lower-carbohydrate training may have a place within an endurance program. However, they stress that these strategies do not eliminate the risks of chronic under-fueling. Athletes still require adequate carbohydrates, protein and dietary fat to support performance, recovery and overall health.
They also cover behaviours associated with disordered eating, the spectrum between structured nutrition and unhealthy restriction, whether runners should deliberately lose muscle mass, and the difficult tradeoffs that can exist between short-term performance and long-term health.
Episode Timestamps
00:00 Is Lighter Always Faster?
00:43 Fat Buffer and Absorption
01:31 Ryan Hall Cautionary Tale
02:38 When Leanness Backfires
03:28 RED-S and the Stress Bucket
06:27 Carb Cycling and Risk
08:43 Macronutrients and Carb Periodization
10:29 The Disordered Eating Spectrum
12:13 Muscle Mass vs Running Goals
13:20 Health and Performance Tradeoffs
14:28 Wrap Up and Thanks
This conversation is provided for general educational purposes and is not individual medical or nutritional advice. Athletes concerned about RED-S, disordered eating or persistent under-fueling should speak with a qualified healthcare professional.
