Increased carbohydrate availability partially attenuates endocrine suppression in response to low-energy availability
Study Details
This new study tested whether carb availability modifies endocrine and metabolic responses to 4 days of low energy availability (LEA) in 16 recreationally active adults 🔍
EA was fixed at ~25 kcal/kg FFM/day in both conditions, while carb availability was ~1.4 versus ~3.7 g/kg/day 🍽️
Carb intake averaged ~4.2 g/kg/day in the low-CHO condition and ~6.7 g/kg/day in the high-CHO condition 🍝
Key Findings
📉 Body mass fell by ~1.3% during both conditions, with no meaningful difference between carbohydrate intakes
💪 Fat-free mass decreased by ~0.7 kg in both conditions, although only the low-CHO condition reached statistical significance
🧬 IGF-1 fell in both conditions, but the reduction was roughly halved with higher carbohydrate availability: ~20% versus ~9%
🩸 Insulin also declined more with low carb availability, although the between-condition interaction was not significant
🧬 Testosterone decreased significantly in the low-CHO condition but not the high-CHO condition, though the difference was not statistically significant
🩸 Leptin fell significantly in women during both conditions, with a smaller numerical reduction with higher carbohydrate availability
🦋 T3 was not significantly altered over the 4 days
🔥 LEA shifted metabolism toward greater fat oxidation and lower carbohydrate oxidation
🚹 These substrate shifts were more strongly influenced by sex than carbohydrate availability, with larger increases in fat oxidation in men
🩸 Maximal blood lactate fell by ~10.5% with low carb availability but was maintained with higher carb intake
📈 Lactate curves also shifted rightward with low CHO, suggesting reduced glycolytic contribution
🚴 VO₂peak and maximal power output were unchanged across both conditions
Conclusion
Higher carb availability may therefore partially attenuate some endocrine and glycolytic consequences of short-term LEA, particularly suppression of IGF-1 🛡️
However, carbohydrate did not eliminate the effects of LEA, suggesting overall energy availability remains the dominant physiological driver ⚠️
During unavoidable short-term energy restriction, maintaining carb intake may help reduce some of the endocrine disturbance associated with LEA ✅
Reference
https://pubmed.ncbi.nlm.nih.gov/42461760/
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