Mild dehydration is the loss of what percent of body weight?

• A. 1%
• B. 2%
• C. 3%
• D. 4%

Answer: (B)

Percent body weight loss from sweating is used to gauge how dehydrated an athlete is. Mild dehydration is defined by about a 2% loss of body weight. You can estimate it by comparing an athlete’s pre- and post-exercise weights and calculating the percentage lost: (pre - post) / pre × 100. At around 2% loss, thirst and dry mouth may appear, urine may be darker, and there can be subtle drops in endurance and performance. Losses around 1% are usually not considered dehydration requiring intervention, while higher losses (roughly 3–4% or more) indicate more moderate to severe dehydration and greater need for rapid fluid replacement and monitoring. This threshold helps guide hydration strategies in training and competition.