Summary: In trained adult athletes participating in a controlled energy availability study, short-term low energy availability (LEA) at 15 kcal·kg FFM⁻¹·day⁻¹, achieved with or without exercise manipulation demonstrated significant alterations in serum metabolome with shifts toward increased fat utilization, enhanced ketogenesis, reduced circulating triglycerides, and decreased amino acid concentrations compared to high energy availability (HEA) at 40 kcal·kg FFM⁻¹·day⁻¹, with metabolic changes occurring regardless of whether LEA was achieved through reduced intake or increased exercise.
| PICO | Description |
|---|---|
| Population | Trained adult athletes participating in a controlled energy availability study. |
| Intervention | Short-term low energy availability (LEA) at 15 kcal·kg FFM⁻¹·day⁻¹, achieved with or without exercise manipulation. |
| Comparison | High energy availability (HEA) at 40 kcal·kg FFM⁻¹·day⁻¹, considered adequate for normal physiological function. |
| Outcome | LEA significantly altered the serum metabolome with shifts toward increased fat utilization, enhanced ketogenesis, reduced circulating triglycerides, and decreased amino acid concentrations regardless of method used to achieve LEA. |
Clinical Context
Low energy availability (LEA) underlies Relative Energy Deficiency in Sport (RED-S), a syndrome affecting health and performance across multiple body systems. Detecting LEA remains challenging because symptoms develop gradually and athletes often underreport dietary restriction.
Metabolomics—the comprehensive analysis of small molecules in biological samples—offers potential for identifying LEA signatures before clinical symptoms appear, enabling earlier intervention.
Clinical Pearls
1. Metabolic Shift Toward Fat Oxidation: LEA triggers a metabolic switch to fat oxidation and ketone production, similar to fasting or low-carbohydrate states. This represents the body’s adaptive response to energy deficit.
2. Amino Acid Reduction Concerning: Decreased circulating amino acids during LEA may reflect protein catabolism, threatening muscle protein synthesis and recovery capacity.
3. Detection Independent of Exercise Mode: Whether LEA was achieved through caloric restriction or increased exercise expenditure, similar metabolomic signatures emerged—supporting the validity of metabolomics as a detection tool.
4. Short-Term Changes Predict Long-Term Risk: Even brief periods of LEA produced measurable metabolic changes, suggesting metabolomics could enable early LEA detection before chronic consequences develop.
Practical Application
Clinicians evaluating athletes for RED-S should consider metabolic indicators alongside traditional assessments. Low T3, elevated cortisol, reduced insulin, and ketosis in a lean, highly active individual should raise suspicion for LEA.
While clinical metabolomics panels are not yet routine, understanding the metabolic signature of LEA can inform interpretation of available laboratory tests.
Broader Evidence Context
RED-S has replaced the older “Female Athlete Triad” concept, recognizing that energy deficiency affects both sexes and impacts multiple systems beyond bone and reproduction. Early detection remains a priority for prevention.
Study Limitations
Short-term controlled setting may not fully replicate chronic real-world LEA patterns. Translation from research metabolomics to clinical testing requires validation in larger, more diverse athletic populations.
Bottom Line
Short-term low energy availability in athletes produces characteristic metabolomic changes—increased fat oxidation, ketogenesis, and reduced amino acids—that may serve as early biomarkers for detecting energy deficiency before clinical consequences develop.
Source: “Blood Metabolites for Detecting Early Low Energy Availability in Athletes.” Read article.
