The Costs of Low Energy Availability in Female Athletes
- projectunlaced
- Aug 19
- 2 min read
Athletes know that training hard is key to improving performance—but what about fueling enough? Low Energy Availability (LEA) happens when the calories you eat aren’t enough to cover both exercise and the body’s basic needs. Even short periods of LEA can trigger changes in stress hormones, immune function, and performance. This study explores how just two weeks of LEA affected female endurance athletes—and why the effects lasted even after a few days of refueling.
Methods
12 female endurance athletes either began a 14 day Optimal Energy Availability (OEA) diet or a Low Energy Availability (LEA) diet with 3 days of refueling. They took blood samples from the athletes before and after each diet phase (OEA and LEA). From these samples, they separated out a specific type of immune cell called PBMCs. Exercise performance was assessed on a bike by a 20-min time trial as well as a time-to-exhaustion test at an intensity of ~110% of VO2 max.
Note About PBMC
PBMC are Peripheral Blood Mononuclear Cells. This group of cells includes lymphocytes (like T cells and B cells) and monocytes. They play an important role in the immune system.
In this study, PBMCs were used to analyze mitochondrial respiration, H2O2 emission, and specific proteins.
Results
LEA increased systemic cortisol by 22%. Cortisol is a stress hormone. Higher levels suggest that LEA puts the body under more physiological stress.
LEA altered several inflammatory-related proteins.
LEA reduced the mobilization of white blood wells with acute exercise.
Power output during the 20-min time trial was 7.8% lower after LEA.
Power output remained 6.7% lower even after the 3 days of refueling.
Conclusions
The increase in cortisol indicates that short-term LEA places greater stress on the body. LEA also impaired exercise performance, with effects persisting even after a refueling period. All in all, for female endurance athletes, even short-term calorie restriction can increase stress on the body, harm immune health, and reduce performance—effects that aren’t quickly reversed by just a few days of refueling. These findings emphasize the importance of minimizing LEA in female athletes.
Citation
Jeppesen JS, Caldwell HG, Lossius LO, Melin AK, Gliemann L, Bangsbo J, Hellsten Y. Low energy availability increases immune cell formation of reactive oxygen species and impairs exercise performance in female endurance athletes. Redox Biol. 2024 Sep;75:103250. doi: 10.1016/j.redox.2024.103250. Epub 2024 Jun 19. PMID: 38936255; PMCID: PMC11260862.