If you drink coffee every day, you may have heard the advice to drink extra water because caffeine can dehydrate you. However, does coffee actually dehydrate you?
For most people, the answer is no. Moderate coffee consumption does not appear to cause dehydration. While caffeine has a mild diuretic effect, the water in a cup of coffee generally provides more fluid than you lose as a result.
In fact, research suggests that coffee can contribute to your daily fluid intake just like many other beverages.
Does Coffee Dehydrate You?
Coffee does not typically dehydrate you when consumed in moderate amounts.
The confusion comes from caffeine. Caffeine is considered a mild diuretic, which means it can temporarily increase urine production. Because of this effect, people have long assumed that drinking coffee causes the body to lose more water than it takes in.
Research suggests that is not what happens under normal circumstances.
According to the Mayo Clinic, caffeinated beverages can contribute to your daily fluid needs. Although caffeine can increase urine production, the fluid contained in caffeinated beverages generally balances that effect when caffeine is consumed at typical levels.
So, while you might find yourself making an extra trip to the bathroom after your morning coffee, that does not necessarily mean you are becoming dehydrated.
What Does the Research Say About Coffee and Hydration?
One of the most frequently cited studies on coffee and hydration was published in PLOS ONE.
Researchers studied 50 habitual male coffee drinkers and compared hydration markers when participants drank coffee with those recorded when they drank water. Participants consumed four 200 mL servings of either coffee or water per day.
The researchers found no significant differences in total body water or several other markers of hydration between the coffee and water trials. They concluded that moderate coffee consumption among habitual coffee drinkers provided similar hydrating qualities to water.
This supports the idea that your daily cup of coffee is not automatically working against your hydration goals.
It is worth noting that this particular study included habitual male coffee drinkers, so its findings should not be interpreted as proving that coffee and water are identical for every person or situation.
Why Does Caffeine Make You Urinate More?
Caffeine can affect the kidneys and temporarily increase urine production, particularly when consumed in larger amounts.
A scientific review published in the Journal of Human Nutrition and Dietetics found that large doses of caffeine can cause a short-term increase in urine output, especially among people who have not consumed caffeine for several days or weeks. The review also found that people who regularly consume coffee or tea tend to develop a tolerance to this effect.
In other words, someone who drinks coffee regularly may experience less of a diuretic effect than someone who rarely consumes caffeine.
The National Academies has also concluded that there is no convincing evidence that caffeine causes a cumulative total body water deficit. Caffeinated beverages can still contribute to total daily water intake.
Is Coffee Hydrating?
Yes, coffee can be hydrating. A brewed cup of coffee is primarily water, and that water still counts toward your overall fluid intake. The National Academies notes that people receive water from a variety of sources, including drinking water, coffee, tea, other beverages, and moisture contained in food.
That does not mean you should replace every glass of water with coffee. Plain water remains an excellent choice for hydration because it contains no caffeine and is easy to consume throughout the day.
Instead, think of coffee as one part of your overall fluid intake rather than something that automatically cancels hydration out.
Can Too Much Coffee Affect Hydration?
The amount of caffeine you consume matters.
Higher doses of caffeine can produce a stronger diuretic effect, particularly if your body is not accustomed to caffeine. Your individual response can also depend on factors such as your caffeine tolerance, activity level, environment, and overall fluid intake.
For most healthy adults, the Mayo Clinic notes that up to 400 milligrams of caffeine per day appears to be safe, although individual sensitivity varies. The caffeine content of coffee can also vary considerably depending on the beans, serving size and brewing method.
If you are exercising heavily, spending time in hot weather or losing fluids because of illness, make water and appropriate hydration a priority rather than relying primarily on caffeinated beverages.
Coffee Hydration: The Bottom Line
So, can coffee make you dehydrated? For most people enjoying coffee in moderation, probably not.
Coffee contains caffeine, and caffeine can have a mild diuretic effect. However, research indicates that the water you consume in coffee generally offsets this effect. Moderate coffee consumption can contribute to your overall daily fluid intake, especially if you are already accustomed to drinking caffeine.
There is no need to think of your morning cup as something you have to “make up for” with an equal amount of water. Enjoy your coffee, drink water throughout the day and pay attention to your body’s thirst cues.
At Java City, we believe coffee can be part of the everyday moments that make your routine a little better. Whether you prefer a light roast in the morning, a smooth medium roast in the afternoon, or a bold cup to start the day, there is plenty to explore.
Frequently Asked Questions About Coffee and Dehydration
Does coffee count toward your daily water intake?
Yes. Coffee contains water and can contribute to your total daily fluid intake. Research and guidance from the National Academies indicate that caffeinated beverages can be included among the sources that contribute to total water intake.
Does caffeine dehydrate you?
Caffeine has a mild diuretic effect and may temporarily increase urine production. However, typical amounts of caffeine consumed in beverages do not appear to cause enough fluid loss to offset the fluid you consume with the beverage.
Is coffee as hydrating as water?
Water is still the simplest choice when hydration is your primary goal. However, research involving habitual coffee drinkers has found that moderate coffee consumption can maintain hydration similarly to water under normal conditions.
Should I drink water after coffee?
You do not need to drink a glass of water after every cup of coffee simply to prevent dehydration. It is still a good idea to drink water regularly throughout the day, especially during exercise, hot weather, or periods of increased fluid loss.
Can drinking too much coffee make you dehydrated?
Large amounts of caffeine may increase urine production more noticeably, particularly in people who do not regularly consume caffeine. Moderate coffee consumption, however, has not been shown to cause dehydration in healthy habitual coffee drinkers.
