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Published on: November 27, 2019
Increased carbohydrate availability partially attenuates endocrine suppression in response to low-energy availability
Valentin Nusser1, Jan Teubner1, Simon A Buerger1
1Department of Health and Sport Sciences, TUM School of Medicine and Health, Technical University of Munich, Munich, Germany.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|July 16, 2026
Summary
Maintaining high carbohydrate availability (CA) during short-term low-energy availability (LEA) partially offsets endocrine declines, particularly insulin-like growth factor 1 (IGF-1). CA also preserves glycolytic function, but substrate utilization shifts during LEA are sex-dependent.
Area of Science:
- Exercise Physiology
- Endocrinology
- Sports Nutrition
Background:
- Low-energy availability (LEA) induces significant endocrine and metabolic adaptations.
- The specific role of carbohydrate availability (CA) in modulating these LEA responses remains poorly understood.
- Understanding CA's influence is crucial for optimizing athletic performance and health under energy-restricted conditions.
Purpose of the Study:
- To investigate whether varying carbohydrate availability (CA) influences endocrine and metabolic adaptations during short-term low-energy availability (LEA).
- To determine the impact of different CA levels on substrate utilization and performance metrics under LEA.
- To elucidate the interplay between CA, LEA, and hormonal responses in recreationally active adults.
Main Methods:
- A randomized crossover study involving 16 recreationally active adults (9 female).
- Participants completed two 4-day conditions of LEA (25 kcal·kg fat-free mass (FFM)-1·day-1) with either low (1.5 g·kg-1·day-1) or high (4.0 g·kg-1·day-1) CA.
- Daily exercise expenditure was standardized (20 kcal·kg FFM-1·day-1), and diets were fully controlled.
Main Results:
- High CA significantly attenuated the LEA-induced decline in insulin-like growth factor 1 (IGF-1) compared to low CA.
- LEA led to increased fat oxidation, a shift not modulated by CA but influenced by sex.
- High CA partially preserved glycolytic function, indicated by mitigated reductions in blood lactate concentrations during exercise.
Conclusions:
- Maintaining higher carbohydrate availability during short-term low-energy availability partially offsets adverse endocrine changes, notably reducing the decline in IGF-1.
- Carbohydrate availability influences glycolytic function preservation under LEA, but its effect on substrate utilization shifts is sex-dependent.
- Maximal exercise performance indices were unaffected by LEA or varying CA levels in this short-term study.
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