Relationship between Energy Availability and Phenotype in Free-Living Athletes.

This study aims to explore the impact of energy availability on body composition, dietary intake, sleep quality, and subjective well-being in free-living Spanish athletes across different sports disciplines. A total of 75 elite and pre-elite athletes (27 women; 24.9±5.9 y) were included. Body composition was assessed by dual-energy x-ray absorptiometry, bioimpedance, and anthropometry; the diet was assessed using dietary recalls and food-frequency questionnaires; sleep quality was determined using a wrist-worn accelerometer; and subjective well-being was evaluated through validated questionnaires. We observed, counter to common hypothesis, that athletes with low energy availability showed higher levels of bone-related markers (i.e., bone mineral content, bone mineral density, and Z-score) compared to those with adequate energy availability (all p<0.05). Despite higher protein intake, athletes with low energy availability consumed fewer carbohydrates than those with adequate energy availability (all p<0.05). No relationship was observed between energy availability and other body composition parameters, sleep quality, or subjective well-being markers (all p>0.05). Overall, these results suggest that factors like metabolic adaptations, activity patterns, and individual behaviors may influence the relationship between energy availability and athletic performance in real-world settings. Low energy availability's complexities extend beyond simple nutritional deficiencies, emphasizing the need for a holistic approach to managing energy availability and optimizing athletes' performance and health.