Why Does Coffee Dehydrate You?

For sure, you have heard so many things, both positive and negative, about coffee. One of the common arguments against coffee is that it can cause dehydration. If you do not drink coffee, you can be easily persuaded not to drink or start to develop a love affair with this bittersweet beverage. If you are coffee lover, you can find one thousand and ways to debunk this myth and still enjoy every sip of a freshly brewed coffee.

The so-called negative effects of coffee are often attributed to its caffeine content. Also found in tea, soda and chocolate, caffeine is a widely consumed substance in every country around the world. It is a known natural stimulant used to perk people up. It is a legal and unregulated substance; however, this famous chemical is often attributed to bad health effects, one of which is dehydration.

The idea that drinking coffee can dehydrate you had surfaced as early as 1928. The study published in The Journal of Pharmacology and Experimental Therapeutics noted an increase in urination among people who drank caffeinated beverages, coffee included. This study led to the belief that coffee was diuretic.

More recent studies

In 2005, Lawrence Armstrong, a professor in the Department of Kinesiology at the University of Connecticut and director of the Human Performance Laboratory, and his team of researchers analyzed whether drinking coffee can cause dehydration.

They controlled the diets of 59 healthy males for 11 days, supplementing their daily consumption with body-mass-appropriate doses of caffeine, administered twice a day via capsule. Throughout the study, the researchers employed 20 different hydration biomarkers, such as urine volume and fluid-electrolyte balance, to assess dehydration.

“The truth of the matter is, a small increase in urine output has little to do with dehydrating the body,” Armstrong told Live Science. “If you drink a liter of water, [urination] will increase. Doesn’t mean you shouldn’t drink water.”

Armstrong’s study showed significant results because it covered beyond the 24-hour period. The study lasted for 11 days and significant data was gathered from the participants to indicate that drinking coffee is not the sole reason for dehydration.

In fact, the groups who took caffeine and the group that took placebo demonstrated hydration indicators like urine volume. The researchers were able to conclude that a higher dose of caffeine would not dehydrate a person, nor would smaller doses.

In another report, BBC Health noted a study conducted by Sophie Killer at Birmingham University in the UK. She not only measured the volume of urine, but tested their blood for signs of kidney function, as well as calculating the total amount of water in the body. The men in the study drank four cups of coffee a day, far more than the average coffee-drinker. Yet, there was no evidence that they were any more dehydrated than those who drank water, alone.

Another study, published in PubMed, observed two groups of people who took increasing doses of caffeine for 11 days. The researchers did not notice a significant increase in urine volume of the caffeine group versus the non-caffeine group.

What is dehydration?

According to WebMD, dehydration occurs when more water and fluids are exiting the bod than are entering the body. With about 75 percent of the body made up of water found inside cells, within blood vessels, and between cells, survival requires a rather sophisticated water management system.

Good thing our bodies have a natural alarm system and our thirst mechanism tells us when we need to increase fluid intake. We lose water constantly throughout the day, as we breathe, sweat, urinate, and defecate. The body can also shift water around to areas where it is more needed if dehydration begins to occur. We can replenish the water in our body by drinking fluids, though some fluids, like sea water, actually dehydrate you because they have too much salt or other dissolved minerals that take extra water to remove.

In most cases, dehydration can be easily managed by increasing your fluid intake. However, some cases of dehydration need immediate medical attention.

What causes dehydration?

Primarily, dehydration happens when we lack water in the body, lost too much water or both. Here are some medical conditions that may cause dehydration:

  • Diarrhea – the most common cause of dehydration and related deaths. The large intestine absorbs water from food matter, and diarrhea prevents this function, leading to dehydration.
  • Vomiting – leads to a loss of fluids and makes it difficult to replace water by drinking it.
  • Sweating – the body’s cooling mechanism releases a significant amount of water. Hot and humid weather, as well as vigorous physical activity, can further increase fluid loss from sweating.
  • Diabetes – high blood sugar levels cause increased urination and fluid loss.
  • Frequent urination – usually caused by uncontrolled diabetes, but also can be due to alcohol and medications such as diuretics, antihistamines, blood pressure medications, and anti-psychotics.
  • Burns – water seeps into the damaged skin and the body loses fluids.

So, why do some people feel that drinking coffee dehydrate them?

There is no specific reason why people feel that way. Based on the several researchers mentioned earlier, caffeine in itself does not cause dehydration. According to Armstrong, for a person to reach a coffee overdose, this person had to consume 10,000 milligrams of caffeine per day. An 8-ounce cup of brewed coffee has 95 milligrams of caffeine, on the average. To reach overdose and dehydration, one must have had 100 cups of coffee in a day.

In addition, a person can exhibit excessive urination after drinking coffee only if this person had been drinking coffee in succession and had no other liquid. By principle, our body will take in all kinds of fluids and process it, leaving the waste product to be carried out by the body through urine. Essentially, if you had been drinking coffee and had no other liquid intake, most likely, you would still be urinating as if you were drinking water.

Finally, the hot nature of coffee can trigger our body to perspire. This is especially true if you are drinking hot coffee during the summer days. Hot coffee adds to the increased temperature that your body is already feeling. As a result, your body releases sweat to cool you down. If you drink coffee often during the summer, you will feel really dehydrated. What you can do to avoid this is enjoy a cold brew, instead of the usual hot brewed coffee.


Does Coffee Make You Dehydrated?

does coffee make you dehydrated
I drink a lot of coffee and have done so for years. These days I drink less coffee in terms of volume than ever before but the coffee I do drink is a bit more potent.

For a while my wife has been telling me that I need to drink other “non-coffee” drinks to stay hydrated but without going out with a purpose to do so I’ve always done pretty good.

I can’t help but recognize the fact that drinking large volumes of coffee almost always means I’m going to have to go pee in the next couple hours but I’m not 100% sure this is due to the diuretic effect of the caffeine or because of the quantity of fluids I’m taking in.

In fact lately as I’ve been drinking a lot of espresso and potent french press coffee I’ve probably been going pee less frequently than before. Even though I’m drinking more caffeine per ounce of fluid I’m not experiencing the same diuretic effect so this led me to this small blurb posted by the Mayo Clinic’s Katherine Zeratsky.

She writes:

“Drinking caffeine-containing beverages as part of a normal lifestyle doesn’t cause fluid loss in excess of the volume ingested. While caffeinated drinks may have a mild diuretic effect — meaning that they may cause the need to urinate — they don’t appear to increase the risk of dehydration.” Source

This kind of answers my question – If coffee is a diuretic then why do I not ever seem to get dehydrated while drinking it?

Looks like the water content in coffee offsets the fluid loss caused by an increased need to urinate after drinking coffee. In short it’s a wash.

My wife however still has hesitations in agreeing with this though so I have to dig deeper.

Does Coffee Make You Dehydrated?

The idea that drinking coffee can dehydrate you had surfaced as early as 1928. The study published in The Journal of Pharmacology and Experimental Therapeutics noted an increase in urination among people who drank caffeinated beverages, coffee included. This study led to the belief that coffee was diuretic.

The so-called negative effects of coffee is often attributed to its caffeine content. Also found in tea, soda and chocolate, caffeine is a widely consumed substance in every country around the world. It is a known natural stimulant used to perk people up. It is a legal substance and unregulated. However, this famous substance is often attributed to bad health benefits, one of which is dehydration.

What is dehydration?

Dehydration occurs when more water and fluids are exiting the body than are entering the body. With about 75 percent of the body made up of water found inside cells, within blood vessels, and between cells, survival requires a rather sophisticated water management system. – WebMD

Good thing, our bodies have a natural alarm system, and our thirst mechanism tells us when we need to increase fluid intake. We lost water constantly throughout the day as we breathe, sweat, urinate, and defecate, we can replenish the water in our body by drinking fluids. The body can also shift water around to areas where it is more needed if dehydration begins to occur.

In most cases, dehydration can be easily managed by increasing your fluid intake. However, some cases of dehydration needs immediate medical attention.

Why do people experience dehydration?

Primarily, dehydration happens when we lack water in the body, lost too much water or both. Here are some medical conditions that may cause dehydration:

  • Diarrhea – the most common cause of dehydration and related deaths. The large intestine absorbs water from food matter, and diarrhea prevents this function, leading to dehydration.
  • Vomiting – leads to a loss of fluids and makes it difficult to replace water by drinking it.
  • Sweating – the body’s cooling mechanism releases a significant amount of water. Hot and humid weather and vigorous physical activity can further increase fluid loss from sweating.
  • Diabetes – high blood sugar levels cause increased urination and fluid loss.
  • Frequent urination – usually caused by uncontrolled diabetes, but also can be due to alcohol and medications such as diuretics, antihistamines, blood pressure medications, and anti-psychotics.
  • Burns – water seeps into damaged skin and the body loses fluids.

What do the Experts Say About It

In 2005, Lawrence Armstrong, a professor in the Department of Kinesiology at the University of Connecticut and director of the Human Performance Laboratory and his team of researchers analyzed whether drinking coffee can cause dehydration.

Armstrong’s study showed significant results because it covered beyond the 24-hour period. The study lasted for 11 days and significant data were gathered from the participants to indicate that drinking coffee is not the sole reason for dehydration.

In fact, the groups who took caffeine and the group that took placebo demonstrated hydration indicators like urine volume. The researchers were able to conclude that a higher dose of caffeine would not dehydrate a person nor smaller doses were.

In another report, BBC Health noted a study conducted by Sophie Killer at Birmingham University in the UK. She did not only measured the volume of urine, but tested their blood for signs of kidney function as well as calculating the total amount of water in the body. The men in the study drank four cups of coffee a day, far more than the average coffee-drinker. Yet there was no evidence they were any more dehydrated than those who drank water alone.

Another study published in PubMed, observed two groups of people who took increasing doses of caffeine for 11 days. The researchers did not notice a significant increase in urine volume of the caffeine group versus the non-caffeine group.

Why do Some People Think That Drinking Coffee Dehydrates Them?

  • Many people blame the caffeine. According to Armstrong, for a person to reach a coffee overdose, this person had to consume 10,000 milligrams of caffeine per day. An 8-ounce cup of brewed coffee has 95 milligrams of caffeine, on the average. To reach overdose and dehydration, one must have had 100 cups of coffee in a day.
  • Many people think drinking coffee causes frequent urination. A person can feel excessive urination after drinking coffee only if this person had been drinking coffee in succession and had no other liquid. By principle, our body will take in all kinds of fluids and process it, leaving the waste product to be carried out of the body through urine. Essentially, if you had been drinking coffee and had no other liquid intake, more likely, you will still be urinating as if you are drinking water.
  • Many people blame the temperature. The hot nature of coffee can trigger our body to perspire. This is especially true if you are drinking coffee during the summer days. Hot coffee adds to the increased temperature that you are already feeling. As a result, your body releases sweat to cool you down. If you drink coffee often during the summer, you will feel really dehydrated. What you can do is enjoy a cold brew instead of the usual hot brewed coffee.

Coffee, in itself, does not cause dehydration. There are several factors that come into play that causes body dehydration.


Does Coffee Dehydrate Your Body?

Whether you’re a coffee lover or not, you may have heard about the possibility of caffeine being a dehydrating substance.

However, there may be some science that claims otherwise!

If you consume caffeine in any beverage, whether it’s coffee or soda, it’s important to know the potential effects that caffeine can have on the body.

In addition, it’s important to know just how much caffeine is too much for your daily consumption.

To give you a clearer look into coffee and the caffeine within it, we’re going to break it down and make caffeine easier to understand.

So read on, learn and enjoy!

Caffeine Is A Diuretic

Many of us are aware that coffee can work as a bit of a diuretic, adding a couple of extra trips to the bathroom than you might take otherwise.

However, one or two cups aren’t going to have you running back and forth from the bathroom all day.

This diuretic characteristic is largely due to the caffeine found within the brew.

Many of us are very aware of what caffeine can do, providing a convenient boost to our mornings.

It’s often a great tool to help us get going when mornings might otherwise be sluggish.

That said, it’s important to not overdo it when it comes to caffeine.

It All Depends On The Dose!

More recent studies on caffeine consumption have shown that in normal amounts, caffeine isn’t going to create enough fluid loss to create dehydration.

However, it’s important to be careful not to overdo it.

Otherwise the balance of fluid consumption and loss can be thrown off somewhat.

It’s also going to be important to make sure that you keep up normal water consumption.

That can help to avoid any problems that a higher amount of caffeine may be able to cause without it.

If you can manage to get by with a lower dose of caffeine daily, that’s also a good option.

There are a number of ways to do this.

You can drink less coffee overall, cutting down the number of cups you drink daily little by little.

Or, you can choose to replace some of your daily cups with decaf.

Otherwise, there is also the option of finding a coffee with less caffeine it, such as a different roast.

How Caffeine Effects The Body

Most of us who are familiar with coffee or other caffeine-containing beverages know some of the more obvious effects.

Caffeine can provide an energy boost, helping us to become more alert.

It can also increase the heart rate, and stimulate the need to rush to the bathroom in some cases.

However, in amounts that are too great it can also cause us to become jittery.

For those who aren’t familiar with them, these jitters tend to make us irritable.

We can also feel very anxious, and like there is an excess of nervous energy in our bodies.

This can get very uncomfortable and it’s definitely a sign that it’s time to tone it down with the caffeine intake.

Caffeine Addiction and Withdrawals

It’s also important to be able to tell when you might have developed a caffeine addiction.

In some cases, it can go unnoticed until there comes a day when you may not have access to coffee or some other caffeine source.

Many who experience caffeine withdrawals can find that they experience aches in their muscles.

In some other cases, you may be more prone to headaches and irritability due to the withdrawal of the caffeine that your body has become used to.

There can also be instances where people find that caffeine might seem to make them tired.

If you notice that you’re beginning to experience withdrawal symptoms, it can be a good idea to try to wean down your caffeine intake.

Like all things, it’s wise to keep this habit balanced.

Caffeine in Coffee

If you’re a coffee lover, then you’ll be happy to know that coffee is a bit different from other caffeine sources.

Things like soda and caffeine pills don’t contain many other ingredients that are helpful to the human body.

However, coffee is known to contain antioxidants that protect your body against various illnesses as well as giving you that boost.

Things like dementia, high blood pressure, liver cancer and even diabetes can be prevented in part by this wonderful beverage.

That said, it’s important to keep in mind that coffee alone isn’t going to ensure these kinds of issues don’t pop up, it’s just one more thing that can help!

Caffeine Limits

Just like anything else in life, it’s important to enjoy coffee as well as the caffeine within it in moderation.

Having too much can have a number of unpleasant effects, some of which were mentioned earlier in this article.

As a general rule of thumb, it’s a good idea to try to remain below 400mg of caffeine on a daily basis.

For those who don’t measure out their milligrams, this is equal to about 4 standard cups of coffee.

Naturally, this can vary depending on who is drinking the coffee as well.

So, Can Caffeine Dehydrate Me?

Overall, the answer is yes. However, this would take an extremely large amount!

For those who regularly consume more than the recommended amount of caffeine on a daily basis, there can be a higher risk of dehydration.

Based on this concept, it’s a good idea to make sure that you tailor your habits accordingly.

If you’re consuming over 400mg of caffeine daily, it’s a good idea to bring down that amount a bit.

You can also choose to drink more water, ensuring that your body is able to get enough of the hydration it needs to continue functioning well.

For most people who maybe have a cup or two of coffee daily, it’s highly unlikely that the amount of coffee in those drinks will be enough to cause dehydration.

As with anyone else, it is still important that you make sure to drink plenty of water.

The dehydration effects with drinking any reasonable amount of coffee will be lessened if your body is well-hydrated.

In addition, water is a very important need just for keeping our bodies running efficiently on a daily basis, with or without coffee.

As a result, it’s a good idea to set the expectation for yourself that you should try to consume the correct amount of water for the needs of your body even if you’re drinking coffee that day as well.

Conclusion

Overall, in most cases coffee isn’t something that is going to come with much of a risk for dehydration.

For those who consume anywhere between one and four cups a day, there shouldn’t be too much worry!

Naturally, it’s important to make sure you’re drinking plenty of water as well, as coffee isn’t something you should rely on to provide all the hydration you need.

If you consume a lot more coffee than most people, you may want to consider toning it down a bit.

Otherwise, you can run the risk of a caffeine addiction or just consuming more caffeine than your body can easily handle.

This can result in unpleasant side effects like jitters, headaches and other kinds of issues that really cause the effects of caffeine to backfire.

As a result, it’s really a great idea to keep your coffee consumption balanced, and combined with plenty of water.

Brian Mounts

Head blogger, editor, and owner of "Top Off My Coffee", a website that has been educating readers about coffee brewing techniques and equipment since 2012.

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