At what percentage of body weight lost does exercise performance begin to be impaired?

Exercise performance begins to be impaired when an individual loses about 2% of their body weight due to dehydration or energy depletion. This percentage is significant because even a small loss of body weight can lead to a decline in physical capabilities. At this threshold, athletes may start to experience decreased endurance, increased perceived effort, and reduced overall performance because the body is not functioning optimally.

The physiological reasons behind this include compromised thermoregulation, delayed muscular response, and altered metabolic processes, all of which can detrimentally impact athletic performance. Therefore, understanding the impact of body weight loss, particularly around the 2% mark, is crucial for athletes and fitness enthusiasts to maintain optimal performance and to avoid the negative consequences associated with dehydration or inadequate energy levels during exercise.