- Although water remains the best choice for staying hydrated, research suggests that moderate coffee consumption contributes to the daily fluid needs of most regular drinkers.
- How coffee affects hydration depends on factors like your caffeine tolerance, total fluid intake, and health status, not just how many cups you drink.
- Dark urine, dizziness, extreme thirst and fatigue can indicate dehydration, but the cause is often not just coffee.
Coffee is one of the most popular drinks in the world, and for most people who drink it, it’s not just a one-cup-a-day habit. It’s your go-to drink for a morning ritual, an afternoon reset, and it’s even the thing you sip while answering your emails. If you drink coffee most of the time, it’s natural to wonder: Does the drink that has you running to the bathroom every few hours actually hydrate you?
We spoke with a few doctors to find out if all those cups of java count toward your daily water intake. They explain how coffee affects fluid balance, when it’s more likely to dehydrate you, and the signs your body may need to replace one of your daily cups with water.
- Susan KaisMD, double board-certified gastroenterologist and hepatologist at UC Health
- Jay LutharMD, DipABLM, triple board-certified internal medicine physician, instructor at Harvard Medical School and founder of Lutanen Health
Does coffee count towards your daily water intake?
When it comes to hydration, coffee has a more complicated reputation than water. It contains water, but also caffeine, which has sometimes been linked to increased fluid loss. “Clearly and simply, water is the best liquid you can drink to stay hydrated,” says Susan Kais, MD, a double board-certified gastroenterologist and hepatologist at UC Health. “Coffee may contribute to your water intake, but caffeine is a natural diuretic, so it can also dehydrate you.” In other words, coffee isn’t a substitute for drinking enough water, but it’s also not the hydration villain it’s sometimes made out to be.
In fact, studies suggest that the relationship between coffee and hydration is more nuanced than the old adage “coffee dries you out.” “Research shows that coffee contributes to hydration in the same way as any other beverage for most people,” says Jay Luthar, MD, DipABLM, a triple board-certified internal medicine physician and founder of Lutanen Health. “That said, you can’t compare it directly to water, because coffee has its own effects.” According to Dr. Luthar, some effects of coffee are positive. For example, the American Heart Association suggests that up to five cups of coffee per day are good for heart health.
“At the same time, coffee also has drawbacks, such as possibly triggering gastrointestinal symptoms or increasing anxiety in some people,” he adds. Most of the negative consequences, like nervousness or even dehydration, usually affect people who don’t drink coffee often. That’s why your regular coffee routine involves more than just one isolated cup. The body adapts to regular exposure to caffeine, which can change the intensity of its effects, for better or worse.
Does coffee dehydrate you?
Experts say whether coffee helps or hurts your hydration depends on your overall habits, including your usual caffeine intake and whether you drink enough other fluids throughout the day. “Caffeine has a diuretic effect, potentially leading to dehydration, but research does not fully support this,” says Dr. Kais. “Data suggests that more than 250 milligrams (mg) of caffeine per day, or about two cups of coffee, may increase short-term urination in some people.”
According to the study Dr. Kais refers to, this short-term effect mainly applies to people who have abstained from caffeine for several days or weeks. Regular caffeine drinkers tend to develop a tolerance to the diuretic effect of caffeine, so their response is much weaker. Plus, even if you notice more frequent trips to the bathroom after caffeine, that doesn’t mean coffee is dehydrating you: “This intake doesn’t necessarily lead to dehydration if taken in moderation and balanced with a good water intake,” adds Dr. Kais.
Generally, if your urine is very yellow, it means it is concentrated and you will probably need to increase your water intake. “But also be aware that vitamins can discolor your urine,” says Dr. Kais. “Ideally, you want to look for light yellow to colorless urine and regular urination throughout the day.”
How much fluid you actually need daily
If coffee can be part of your daily fluids, the next question is how much fluid your body actually needs. Although there is a general range, there is no single number that fits everyone. “Recommendations for water intake guidelines vary, but according to the National Academy of Medicine, an adequate intake for an average adult man is about 13 to 15 cups, and for an adult woman it is about 9 to 11 cups, with one cup equaling 8 ounces,” says Dr. Kais. “So, a normal bottle of water typically contains 16 ounces. Higher amounts may be needed with physical activity or with exposure to various climates, such as hot, humid, dry climates and high altitudes.”
Think of these amounts as a useful reference rather than a daily need set in stone. Many other factors can cause your needs to increase or decrease. “The commonly cited baseline intake (around 8 cups per day) is a reasonable starting point, but it is not a universal guideline,” says Dr. Luthar. “Larger body size increases fluid needs, as does fever or illness.”
Both doctors also warn that certain health conditions can change the way your body handles fluids. If you have gastrointestinal upset, vomiting, or fever, you may need more fluids. “A person with heart failure or kidney disease may need to actively restrict their fluid intake rather than encourage it,” adds Dr. Luthar. In this case, it is best to consult your doctor about the right amount of fluid for your specific condition, rather than following general hydration advice.
Signs that you are dehydrated
No matter how much coffee you drink, you should always be aware of how you feel. According to Dr. Kais, signs of dehydration can start with a fluid deficit of as little as 2% and often include dark urine, fatigue, extreme thirst, feeling dizzy or dizzy, or headaches.
“Serious warning signs of dehydration and the need for immediate medical attention include a rapid heartbeat, feeling abnormally confused or drowsy, feeling like you want to pass out, and/or the inability to tolerate or keep down fluids,” says Dr. Kais. These symptoms indicate that your body needs more fluids, but they don’t automatically mean that coffee is the cause. Your overall fluid balance depends on everything you drink, lose, and replace throughout the day.
For most people who drink coffee regularly, dehydration is more likely to come from an overall lack of fluids than from moderate coffee consumption. “Typically, if someone is experiencing symptoms of dehydration, I look elsewhere (like general fluid intake, heat exposure, excessive sweating) before looking at coffee,” says Dr. Luthar. For regular coffee drinkers, the solution is usually not to eliminate caffeine, but to make sure the rest of your fluid intake meets your body’s needs. Someone completely new to caffeine may need to be a little more careful.
Gn Health
