Fagerberg Petter
Karolinska Institutet.
Int J Sport Nutr Exerc Metab. 2018 Jul 1;28(4):385-402. doi: 10.1123/ijsnem.2016-0332. Epub 2018 May 3.
Energy availability (EA) is a scientific concept describing how much energy is available for basic metabolic functions such as reproduction, immunity, and skeletal homeostasis. Carefully controlled studies on women have shown pathological effects of EA < 30 kcal/kg fat-free mass (FFM), and this state has been labeled low EA (LEA). Bodybuilding is a sport in which athletes compete to show muscular definition, symmetry, and low body fat (BF). The process of contest preparation in bodybuilding includes months of underfeeding, thus increasing the risk of LEA and its negative health consequences. As no well-controlled studies have been conducted in natural male bodybuilders on effects of LEA, the aim of this review was to summarize what can be extrapolated from previous relevant research findings in which EA can be calculated. The reviewed literature indicates that a prolonged EA < 25 kcal/kg FFM results in muscle loss, hormonal imbalances, psychological problems, and negatively affects the cardiovascular system when approaching the lower limits of BF (∼4%-5%) among males. Case studies on natural male bodybuilders who prepare for contest show muscle loss (>40% of total weight loss) with EA < 20 kcal/kg FFM, and in the study with the lowest observed BF (∼4 kg), major mood disturbance and hormonal imbalances co-occurred. Studies also underline the problem of BF overshoot during refeeding after extremes of LEA among males. A more tempered approach (EA > 25 kcal/kg FFM) might result in less muscle loss among natural male bodybuilders who prepare for contest, but more research is needed.
能量可利用性（EA）是一个科学概念，描述了有多少能量可用于基本代谢功能，如生殖、免疫和骨骼稳态。对女性进行的精心对照研究表明，当EA低于30千卡/千克去脂体重（FFM）时会产生病理影响，这种状态被称为低能量可利用性（LEA）。健美运动是一项运动员通过展示肌肉线条、对称性和低体脂率（BF）来竞争的运动。健美比赛准备过程包括数月的进食不足，从而增加了发生LEA及其负面健康后果的风险。由于尚未对自然状态的男性健美运动员进行关于LEA影响的严格对照研究，本综述的目的是总结从之前相关研究结果中可以推断出的内容，在这些研究中可以计算EA。综述文献表明，当男性接近低体脂率下限（约4%-5%）时，长时间的EA低于25千卡/千克FFM会导致肌肉流失、激素失衡、心理问题，并对心血管系统产生负面影响。对为比赛做准备的自然状态男性健美运动员的案例研究表明，当EA低于20千卡/千克FFM时会出现肌肉流失（超过总体重减轻的40%），并且在观察到的最低体脂率（约4千克）的研究中，同时出现了严重的情绪障碍和激素失衡。研究还强调了男性在经历极端LEA后再进食期间体脂率过度上升的问题。一种更为适度的方法（EA > 25千卡/千克FFM）可能会减少为比赛做准备的自然状态男性健美运动员的肌肉流失，但还需要更多的研究。
