During physical activity, how much water loss in mL does 1 gram of body mass lost represent?

When a person loses body mass during physical activity, the loss is primarily due to the excretion of fluids through sweat and respiration. The established guideline is that for every 1 gram of body mass lost, approximately 1 mL of water is lost. This relationship is significant because it helps individuals understand the importance of hydration and the need to replace fluids during exercise.

By recognizing that a 1:1 ratio exists (1 gram of body mass loss correlates with 1 mL of water loss), athletes and those engaged in physical activities can gauge their hydration needs more effectively. This ratio is essential for coaches and nutritionists working with athletes to ensure optimal performance and recovery.