Paul Laursen, PhD, and Dr. Phil Maffetone: Rethinking The Role of Fat Oxidation At High Intensities, Plus Practical Diet and Training Applications To Yield Results and More

August 29, 2016


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Dr. Phil Maffetone returns along with a new special guest, Paul Laursen, PhD, an adjunct professor at Auckland University and performance physiologist who leads the Performance Physiology Team at High Performance Sport New Zealand, which helps Olympic athletes and hopefuls. Paul has published more than 100 refereed manuscripts in moderate-to-high impact exercise and sports science journals, and his work has been cited more than 3,000 times. On this show we talk about one of Paul’s recent papers relating to fat burning at high intensities and why the findings offer ground-breaking information for the world of exercise physiology by giving us a further understanding on how much fat-burning athletes can achieve.


Respiratory Exchange Ratio (RER)

  • Is the respiratory exchange ratio (RER) as accurate as we’ve been led to think?
  • Brief definition/refresher on RER
  • “When the intensity is high; when breathing becomes difficult and talking would be an effort; lactic acid is being formed and when this happens the acid will be buffered by a buffer that the body naturally contains: bicarbonate. As soon as this starts to happen bicarbonate will release CO2 and water. Thus we have another source of CO2, that is not directly related to carbohydrate and fat oxidation. In short, the method of calculating carbohydrate and fat burning cannot be used at high intensities.” – What is Fat Max by Asker Jeukendrop
  • “This non-respiratory CO(2) excretion can invalidate use of the RER for determination of fat and carbohydrate oxidation.”
  • Discussion of this study and implications 
  • Transition…

Fat Burning at High Intensities: More Than We Thought?

  • Get the full text here of Paul’s study: Rethinking the role of fat oxidation 
  • Can we/do we actually burn a higher % of fat at higher intensities than we’ve been led to believe or told even with lab testing?\
  • Fat oxidation is explaining performance at high-level intensities
  • Can we maintain the same high level of performance burning that much fat?
  • “Highly trained participants sustain higher work rates with substantially greater fat oxidation rates, but similar CHOox rates, during intermittent high-intensity exercise.”
  • Both substrates–CHO and FAT–are important
  • It’s not about low-carb diets, it’s about highly trained athletes
  • What were diets of the well-trained (WT) subjects vs recreationally trained (RT)?
  • WT had more of a “mixed” diet but were still great fat-burners due to sheer volume of training (25-35 hrs a week)

Practical Applications

  • How to fuel for these results
  • Fueling approach for maintaining health and performance. Discussion each of our perspectives, gender differences, etc.
  • The importance of individualization with diet and health plan
  • The “Peter Attia” approach to diet for health and longevity.
  • More on pros and cons of too low carb/keto for athletes; can backfire it on our health and performance?
  • Besides diet, what about training variables to be a better fat burner i.e. volume and intensity?
  • Should we be utilizing more high-intensity to be a better fat-burner and when to add this intensity….Phil and Paul each give their thoughts.
  • Principle of specificity

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