Will Coffee Hydrate You?

cup of black coffee

by Erin Marissa Russell

Are you wondering about whether coffee will hydrate you? If you’re like us, you’ve heard conflicting information. Yes, coffee’s main ingredient is water, but what about the diuretic properties of caffeine? We’re ready to explain how coffee affects hydration, so just keep reading to find out more.

Is Coffee a Diuretic?

For one thing, you’d need to consume a pretty significant amount of coffee for the diuretic effect to happen. One study found that for coffee to have a diuretic effect, you need to consume five cups of brewed coffee each day. That equals out to 40 ounces or 1.2 liters of coffee daily. Another project saw the effect after consuming three cups of coffee in a single sitting.

(A diuretic effect is when your body makes more urine than it normally would in response to a certain substance.) Coffee can cause a diuretic effect in response to the caffeine it contains if enough coffee is consumed. Studies based on lower, more moderate levels of coffee consumption showed that drinking coffee was just as hydrating as drinking water. One study found that coffee was just as hydrating as water at up to three to six cups per day.

Another thing to consider is that, when you drink coffee regularly, the diuretic effect of the coffee decreases. That means the more regular of a coffee drinker you are, the less likely it is that you’ll experience increased urine output when you drink coffee. Conversely, if you are an occasional coffee drinker, you’re more likely to see the diuretic effect of coffee when you drink it.

But you may be wondering just how much of a diuretic effect coffee has when enough coffee is consumed to trigger the effect. The project that observed a diuretic effect after three cups of brewed coffee in a single serving found that afterward, only 3.7 ounces more urine was produced as compared with consuming non-caffeinated beverages. Even when the diuretic effect happens, you don’t lose more fluid than you take in, so the overall effect of drinking coffee is hydrating.

Caffeine and the Diuretic Effect

Different types of coffee contain different levels of caffeine, which can influence how much of a diuretic effect the coffee causes if enough is consumed. The more caffeine your coffee contains, the more likely it is to have a diuretic effect.

  • Brewed coffee: Brewed coffee may be prepared in an automatic drip machine, French press, or percolator. It is the most commonly made type of coffee in the United States. Eight ounces of brewed coffee contains an average of 95 mg of caffeine, between 70 and 140 mg.
  • Espresso: Espresso doesn’t contain quite as much caffeine as brewed coffee, unless you consider the comparison by volume instead of how it’s usually served. A single shot of espresso (one to 1.75 ounces) contains 63 mg of caffeine.
  • Instant coffee: This quick mix for coffee drinkers is made of freeze-dried or spray-dried coffee beans. It contains less caffeine than brewed coffee. Eight ounces of instant coffee contain between 30 and 90 mg of caffeine. 
  • Decaffeinated coffee: Decaffeinated coffee has had at least 97 percent of its caffeine removed, so it contains much less caffeine than other coffee options. Eight ounces of decaf coffee contains, on average, 3 mg of caffeine, between 0 and 7 mg.

We’ve learned about when the diuretic effect kicks in and how it’s linked to caffeination. We’ve also discussed just how much fluid loss occurs when the diuretic effect happens. What we determined is that the diuretic effect requires a certain level of caffeine consumption before it applies. And even when the diuretic effect applies, the amount of fluid lost is not more than the amount taken in with the coffee, so the overall effect of drinking coffee is hydrating. 

That said, if you are looking for hydration, water is your best option. It’s widely available, inexpensive, and contains no caffeine or calories.

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