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Introduction
Dr. José Areta and colleagues recently carried out a human intervention study examining how a pronounced, short-term energy deficit interacts with an aerobic training stimulus to shape endocrine, metabolic, and skeletal muscle proteomic adaptations.
The core premise is that “low energy availability” is often discussed in a largely unidirectional risk framework, yet human physiology evolved under intermittent energy scarcity, and therefore adaptive responses may be more nuanced than “energy deficit equals impaired adaptation.”
The study used tightly controlled diet and exercise, repeated muscle biopsies, and dynamic proteomic profiling to quantify both abundance and synthesis rates of hundreds of individual muscle proteins. This enables a more granular view of “muscle quality” and phenotype than traditional bulk muscle protein synthesis measures.
The findings were incredibly interesting and could have implications for how we view the impact of energy deficits and exercise response.
We discuss the implications for athletes who routinely encounter transient within-day or multi-day energy deficits, for weight loss contexts, and for broader questions around healthspan and ageing biology.
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- Main study discussed: Nishimura et al., 2025 – Endocrine, Metabolic, and Skeletal Muscle Proteomic Responses During Energy Deficit With Concomitant Aerobic Exercise in Humans
- Other relevant papers:
- Speakman, 2020 – Why does caloric restriction increase life and healthspan? The ‘clean cupboards’ hypothesis
- Areta, 2023 – Physical performance during energy deficiency in humans: An evolutionary perspective
- Melin et al., 2023 – Direct and indirect impact of low energy availability on sports performance
- Areta et al., 2021 – Low energy availability: history, definition and evidence of its endocrine, metabolic and physiological effects in prospective studies in females and males
- Prior episode: #508: Why Athletes Can Achieve High Performance During an Energy Deficit – Jose Areta, PhD
- X: @jlareta
- [02:27]Guest introduction
- [03:28]Research background and study design
- [12:18]Study findings: weight loss and endocrine responses
- [15:47]Muscle adaptations and proteomic analysis
- [21:47]Interpreting the results: evolutionary and practical implications
- [26:57]Mitochondrial proteins and muscle adaptation
- [28:44]Energy deficit as a stressor
- [34:26]Case study: female tour de france athlete
- [40:20]Implications for clinical populations
- [41:44]Future research directions
- [46:48]Key ideas segment (Premium subcribers only)
Guest Information
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His research focuses on how manipulating energy intake, particularly via dietary carbohydrate, protein, and fat, interacts with exercise training to influence skeletal muscle metabolism, physiological adaptation, and physical performance, with particular interest in the endocrinological and metabolic responses to energy restriction/availability in active populations.
Danny Lennon has a master’s degree (MSc.) in Nutritional Sciences from University College Cork, and he is the founder of Sigma Nutrition.
Danny is currently a member of the Advisory Board of the Sports Nutrition Association, the global regulatory body responsible for the standardisation of best practice in the sports nutrition profession.
Introduction to this Episode
Dr. José Areta and colleagues recently carried out a human intervention study examining how a pronounced, short-term energy deficit interacts with an aerobic training stimulus to shape endocrine, metabolic, and skeletal muscle proteomic adaptations.
The core premise is that “low energy availability” is often discussed in a largely unidirectional risk framework, yet human physiology evolved under intermittent energy scarcity, and therefore adaptive responses may be more nuanced than “energy deficit equals impaired adaptation.”
The study used tightly controlled diet and exercise, repeated muscle biopsies, and dynamic proteomic profiling to quantify both abundance and synthesis rates of hundreds of individual muscle proteins. This enables a more granular view of “muscle quality” and phenotype than traditional bulk muscle protein synthesis measures.
The findings were incredibly interesting and could have implications for how we view the impact of energy deficits and exercise response.
We discuss the implications for athletes who routinely encounter transient within-day or multi-day energy deficits, for weight loss contexts, and for broader questions around healthspan and ageing biology.
About the Guest
Dr José L. Areta is an Associate Professor in Exercise Metabolism and Nutrition in the School of Sport and Exercise Sciences at Liverpool John Moores University (LJMU). His research focuses on how manipulating energy intake, particularly via dietary carbohydrate, protein, and fat, interacts with exercise training to influence skeletal muscle metabolism, physiological adaptation, and physical performance, with particular interest in the endocrinological and metabolic responses to energy restriction/availability in active populations.
Useful Terminology for this Episode
- Energy availability (EA) – Commonly defined as (energy intake − exercise energy expenditure) relative to fat-free mass; intended to represent the energy “left over” for physiological function after accounting for exercise costs.
- Low energy availability (LEA) – A state in which energy availability is sufficiently low to provoke compensatory endocrine and physiological responses that may prioritise immediate survival needs over longer-term processes (e.g., growth, reproduction, some aspects of tissue remodelling).
- Dynamic proteomic profiling – A method combining stable isotope labelling (e.g., deuterium oxide) with mass spectrometry to quantify synthesis/turnover and abundance of individual proteins across a tissue proteome, rather than only “bulk” protein pools.
- Absolute synthesis rate (ASR) – In this study, a protein-by-protein estimate of synthesis (and related turnover dynamics), allowing detection of which specific pathways or structural networks are up- or downregulated under different conditions.
- Mitochondrial proteostasis – A set of processes that maintain mitochondrial function by repairing or removing damaged components and supporting remodelling.
- Extracellular matrix (ECM) remodelling / muscle fibrosis – The ECM provides structural scaffolding and force transmission; with ageing and some disease states, ECM accumulation can contribute to “fibrosis” (increased stiffness and altered muscle function). This study observed reduced abundance/synthesis of several ECM proteins during energy deficit with exercise.
