Stronger with Time Breaking Down RED-S, Low Energy Availability, Fasted Training & Recovery for Body Composition - with Dr Tony Boutagy
🌐 Visit → tonyboutagy.com
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The fitness industry prescribes energy deficits without the framework to know when a deficit becomes harmful. This episode translates the RED-S research into practical application for coaches and individuals working on body composition.
In this episode we breakdown the key concepts from recent conversation with Professor Louise Burke.
You'll learn:
Low energy availability (the exposure) vs RED-S (the syndrome) - why the distinction matters for application
Why fat-free mass, not total body mass, is the correct denominator for energy availability
The threshold numbers: ~20 cal/kg FFM for fat loss; below 15 cal/kg FFM where adverse consequences are well-documented
Which systems are affected first - reproductive hormones and bone turnover - and how quickly (research shows within five days at 10 cal/kg FFM, which the transcript notes is not uncommon in physique sport)
Why metabolic adaptation is a consequence of RED-S, not a separate phenomenon
What the evidence does and doesn't support on sex differences in fasted exercise, including the kisspeptin hypothesis
Why fasted training and low energy availability are not the same thing
The 2023 RED-S questionnaire toolkit
Prevention: returning to energy balance (30–40 cal/kg FFM) one to two days per week
Recovery: stepwise calorie increase and gastrointestinal adaptation
Key insight: Low energy availability is the exposure; RED-S is the syndrome.
Fasted training is not the same as low energy availability.
These distinctions are foundational to applying this research correctly.
Topics: RED-S, low energy availability, fat-free mass, metabolic adaptation, fasted training, kisspeptin, body composition, physique sport, Louise Burke, Stronger With Time
RESOURCES & LINKS
Dr Tony Boutagy → tonyboutagy.com
Professor Louise Burke - Australian Catholic University → https://www.acu.edu.au/research-and-enterprise/our-research-institutes/mary-mackillop-institute-for-health-research/our-people/louise-burke
IOC RED-S CAT 2 Tool (PDF) → https://stillmed.olympics.com/media/Documents/Beyond-the-Games/Health-and-Wellbeing/2023-IOC-REDS-CAT2.pdf
IOC 2023 Consensus Statement on RED-S → https://pubmed.ncbi.nlm.nih.gov/37752005
Sports Dietitians Australia → https://www.sportsdietitians.com.au
Polar H10 heart rate monitor → https://www.polar.com/en/sensors/h10-heart-rate-sensor