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Does Coffee Dehydrate You?
Asked: Does coffee dehydrate you? Give citations and check each one actually supports the claim
What the evidence says for moderate drinkers
No
Moderate coffee does not dehydrate you
Caffeine is a mild, temporary diuretic, but the water in coffee more than compensates — net fluid balance stays unchanged [2]
How much coffee do you drink?
Coffee is a mild, temporary diuretic, but the water it contains more than compensates, so net fluid balance stays unchanged [2]. The dehydration belief traces to a flawed 1928 study that gave non-coffee drinkers the caffeine equivalent of five to eight cups at once [2].
Good to know
3–4 cups daily [2]
Safe amount
Mild and temporary
Diuretic effect
Unchanged
Net fluid balance
The Mayo Clinic, the FDA and the International Society of Sports Nutrition all state that moderate coffee consumption does not cause dehydration [2].