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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