# A Proposal for a Standardized Approach to Inducing Low Energy Availability in Athletes
## 4 Discussion
### How Long Is Enough to Induce LEA Clinical Effects?  
Excellent work that has been done so far gives us an insight into duration of LEA. In females, [PERSON] and [PERSON] [19] showed a low-T3 syndrome in exercising women due to EA = 30 kcal/kg FFM/day in only four days. A second important work was conducted on sedentary women that showed a disruption in pulsatility luteinizing hormone under the threshold of 30 kcal/kg FFM/day in only five days [5]. Induced LEA in 3 days in active women resulted in a significant decrease in bone formation [18].  
Previous research by [PERSON] compared effects of LEA on bone formation with a similar approach as the high-EEE and low-EI protocol [18]. The protocol used in that research lasted only three days and found no differences in hormone concentrations (IGF-1, T3, insulin, leptin and 17\(\beta\)-estradiol). However, bone formation was reduced in the dietary energy restriction group. The subjects included were eumenorrheic women. As often recognized, men might not experience the same consequences of suboptimal EA as women. In addition, there is an important difference between sedentary/moderately active subjects and athletes. Longer intervention studies on athletes might provide more relevant data on reduced EA duration that produces health/performance detriments. Four weeks of reduced EA in elite male rowers induced decreased Resting Energy Expenditure (REE). The study design comprised of intensified training that was not matched by an optimal EI [31]. A similar design on cyclist elicited a decrease in REE in 3-week intensified  
Figure 3: The difference in lowering EA to an absolute threshold value (30, 20 and 10 kcal/kg FFM/day) or relative to baseline values (75%, 50% and 25%) in a more individualized manner on 3 representative subjects.  
training load [32] followed by a two week recovery period. There was no significant difference in T3 and leptin. Importantly, they already detected aerobic and anaerobic performance decline.  
This suggests reduced EA in men could have negative effects in three weeks or less. We speculate athletes do not exhibit critical changes in health and performance in 3 or 5 days as shown in sedentary/active females. We hypothesize athletes possess a greater ability of sustaining physical stress and energy deficiency. To show any meaningful changes of LEA in athletes, we suggest protocol should last at least 2 weeks. This is also a duration of typical intensified period in athlete's periodization process. Anything less can cause acute changes that might not affect athlete in long-term.  
To summarize, there is currently no answer on critical duration of LEA. We might discover more by firstly determining the threshold. Then, we suggest protocols should be designed to explore what is the shortest duration of LEA that athletes can withstand without important changes in their performance and health. This is not only important for health-safety of the athletes in real life but also for the participants in future studies. Based on our current knowledge, starting protocols at 14 days might be the most appropriate strategy.