Dehydration and Rehydration

Dehydration and Rehydration

A hydrated body recovers more quickly from physical and mental fatigue

According to the American College of Sports Medicine, “Thirst is a signal that your body is headed toward dehydration. Therefore, it is important to drink before you feel thirsty… Thirst is not a good indicator of hydration and should not be used to monitor hydration status.”[1]

Dehydration, even mild dehydration, has a myriad of physical and psychological effects including: irritability reduced cognitive function, headaches, reduced physical performance, and lethargy. Most casual athletes (golf and tennis) can lose up to 3 liters of water per hour. Mild dehydration is defined as losing as little as 2% of fluid body weight. The effects of moderate dehydration are much more dramatic and can lead to serious consequences such as heart attack and heat stroke.

  • A hydrated body recovers faster from:
    • Fatigue
    • Over-indulgence
    • Illness
    • Jetlag & travel
    • Exercise
    • Climate exposure

H2ORS - Hydration Chart

Energy drinks (particularly those with caffeine) as well as alcoholic beverages have a diuretic effect on the body and accelerate dehydration and by extension worsen the effects. As such, “Caffeinated drinks are not recommended when rapid rehydration after exercise is desired because caffeine can promote modest diuresis.”[2] The same is true of alcohol, but to a larger extent.


[1] American College of Sports Medicine Roundtable on Hydration and Physical Activity: Consensus Statements

Douglas J. Casa, PhD, ATC, FACSM*, Priscilla M. Clarkson, PhD, FACSM, and William O. Roberts, MD, FACSM

[2] Reprinted with permission of the American College of Sports Medicine. Copyright © 2011 American College of Sports Medicine.