Fluid balance

Factsheet for professionals

• Water makes up about sixty percent of body weight. As every system in the body depends on the availability of fluids, even mild dehydration can impair bodily functions and performance.
• Fluid requirements vary greatly between individuals and can alter with climate and physical activity levels. Recommendations on specific fluid choices also vary between countries.

Coffee, caffeine and fluid balance

• It is commonly reported that drinking caffeinated coffee can lead to dehydration. Recent scientific evidence, however, does not support this commonly held belief.

• Coffee drinking in moderation contributes to our fluid intake and does not lead to dehydration or significant loss of body water^1,2.

• Whilst caffeine may have a small diuretic effect, this effect is not strong enough to counter-balance the benefits of fluid intake from coffee drinking. Black coffee contains more than 95% water.

• During exercise, the evidence shows that, not only is moderate caffeine intake beneficial for endurance performance, it does not contribute to body dehydration^3,4.

• Advice to abstain from drinking moderate amounts of caffeinated coffee in order to maintain adequate fluid balance is unfounded.