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Can Coffee Dehydrate You?

I bet you filled your cup just before you came to this article, and you’re wondering whether you’ve had too much coffee already.

Well, we all experience such self-doubt, more so with so many articles saying coffee makes us thirsty.

The National Coffee Association found that an average American drinks three or more cups of coffee daily.

How much caffeine is in there?

Plus, is coffee dehydrating?

Yes, if you consume a lot of coffee, you experience mild diuretic effects due to caffeine. However, if you’re drinking the usual three to four cups to supplement other beverages and water, you’ll not have adverse effects.

Is Coffee as Dehydrating as Alcohol?

cup of coffee and glass of alcohol

No, alcohol will dehydrate you more and faster than coffee, so consuming the two together is not the best choice.

Alcohol has diuretic effects, meaning it induces water loss. Even though coffee is also a diuretic, you’ll only have mild effects from it. When you sip your coffee, it reaches the bloodstream through the stomach lining in about 15 minutes.

The small intestines also play this absorption role, and caffeine stays in your bloodstream for many hours, though half of the amount you drink is out of the system in six hours. Therefore, the peak of any effects is in the first hour after taking your cup of coffee.

Alcohol, on the other hand, causes your renal system to eliminate water fast. The problem worsens when you consume more alcohol and less water as alcohol floods your bloodstream within minutes by seeping through the stomach lining.

Once it is in your bloodstream, there’s no stopping which organ it can reach, even your brain. You’ll experience all symptoms, from sluggishness to trembling fingers. This fast absorption process is the reason you get alcohol-smelling breath because it reaches your lungs, and you exhale it. When it enters the liver, the system converts it into acetaldehyde, a toxic substance that makes the liver overwork to get rid of it.

On top of that, alcohol inhibits the production of vasopressin. This antidiuretic hormone enhances water retention, so without it, your kidneys overproduce urine. That’s how you end up dehydrated.

Further, you are more dehydrated when you consume alcohol because it is faster to flush out water than to process alcohol.

It’s interesting that alcohol can dehydrate you, yet its composition is only 5% alcohol, and the rest is water. If you take 200 ml of beer, you can urinate up to 320 ml, not 200 ml. It means that if you’re taking beer all day without other supplementary drinks, you’re likely to be dehydrated fast.

Drinking water alongside alcohol may reduce the risk of dehydration as your body gets a sufficient amount to function adequately.

Is Coffee a Diuretic?

woman studying drinking coffee

Coffee contains caffeine, which is a diuretic. Caffeine is popular globally, loved for its benefits. For instance, it improves mental alertness, treats tiredness, improves physical performance, and induces weight loss.

Though it’s a diuretic, you only experience the diuretic effect when you consume large quantities of this beverage. Since factors like age, health, and genes control how fast you can metabolize coffee, you may have some caffeine circling in your brain hours after drinking it.

The molecules in caffeine are almost similar to those of a neurotransmitter called adenosine. Hence, caffeine molecules attach to the receptors of adenosine, whose signals tell the brain it’s time to rest.

These caffeine molecules don’t decrease neural activity, so you’re less likely to feel sleepy. Plus, the increase in neutral activity sparks the production of adrenaline, and you’re least likely to fall asleep with such a boost of adrenaline in your system.

However, when it comes to losing water through urine, you’re least likely to get that problem with coffee unless you gulp endless cups.

Consuming more than 500 mg of caffeine can have diuretic effects as it increases blood flow in your kidneys. This prompts your system to eliminate more water in urine. When this happens, you lose more water than your body can preserve for various functions, which leads to a slow metabolic rate, poor kidney function, and skin problems.

You’ll rarely experience the effects of caffeine, such as insomnia and rapid heart rate, when your daily intake is less than five cups of coffee. That’s about 400 mg of caffeine.

The study quoted by many to confirm the dehydrating effects of coffee is a 1928 research that observed three men for two winters. Its findings stated that when the three men drank caffeinated water after abstaining from coffee or tea, they urinated 50% more. However, this diuretic effect diminished when they resumed taking coffee regularly.

Can You Consider Coffee as Water Intake?

woman pouring coffee on a cup

Yes, coffee contributes to your daily fluid intake when you take it in moderation. Even if you don’t get all the benefits you’d get by taking pure water only, you’ll still net the hydrating benefits of your coffee. It can be part of your food and drinks intake as you get hydrated by vegetables, fruits, and many other items in your diet.

However, you can’t substitute all the daily fluid for caffeinated drinks. When you combine all of them, your system may stay hydrated but at the expense of taking in more caffeine.

For example, when you take brewed coffee, brewed black tea, an energy drink, and cola, each in eight oz, your body has a total of 194 mg of caffeine from 32 oz. Eventually, taking only caffeinated drinks counters the moderation requirement to prevent the diuretic effects of caffeine.

In a study conducted on 50 men who drank between 3 and 6 cups of coffee daily, the results concluded that drinking coffee in moderation can have the same hydrating effects as water. The participants, aged 18 to 46 years, drank four mugs of black coffee daily, and in the water trial, they took four cups of water daily.

They didn’t consume alcohol or participate in physical activity from a day before the water or coffee trial. The total body water of the participants was constant, but they had a slight decrease in body mass of about 0.2%.

However, clinical dehydration ranges from 1% to 3%, so the effect experienced by these participants didn’t amount to it. The coffee trial showed increased urinary sodium, but it was more on day 1 of the study only, and it decreased gradually from then on as their bodies adjusted.

Why Does Coffee Make Me More Thirsty?

The first gulp wets your mouth and has satiating effects on thirst. But, a few cups later, you realize there’s no breakthrough, and you’re still thirsty.

When taken in large quantities, coffee increases blood flow to your kidneys and hampers your body’s ability to reabsorb water and sodium. Thus, you experience increased water loss that tells your brain it’s time to quench your thirst. However, this water loss varies depending on caffeine levels in your cup, as we discussed earlier.

Increased thirst may also come from reaching out for coffee instead of quenching your thirst with water in the first round. If the nagging thought persists, you reach out for another caffeinated drink like cola. Eventually, you consume more than the recommended amount of caffeine, leaving you with no space for some water to counter diuretic effects.

What Are the First Signs of Dehydration?

Dehydration means there is less water in your body than your daily intake. When you lose water and sodium, it interferes with ordinary functions in your system, such as temperature control. But, you have to be dehydrated to a large extent, meaning you’re not taking water, tea, or other beverage to reach the over 2 liters needed in a day.

The first symptoms of dehydration are dizziness or lightheadedness, accompanied by a headache. Your urine also changes from clear to dark-colored urine as the hours of dehydration increase. The visits to the loo also decrease since you have no water to pass as urine. Further, you may experience physical weakness and poor concentration.

When you’ve consumed a lot of caffeine, you may experience sleeplessness, a rapid heartbeat, and restlessness. The symptoms vary from one person to another as some experience headaches whenever they take caffeinated drinks.

Seizures come when your caffeine intake is about 1,200 mg or 0.15 tablespoons in pure form, which comes to about 0.45 of a teaspoon. A teaspoon of pure caffeine has the same caffeine level as 28 cups of coffee. So you see, you’ll be overdoing it.

The symptoms worsen if you don’t start a rehydration plan as soon as possible to restart normal body functions.

Is Decaf Coffee Dehydrating?

Unfortunately, decaf coffee also contains caffeine, so it has mild diuretic effects when you drink a lot of it. In an 8-ounce cup, you’ll drink between 2 and 15 mg of caffeine, which is minimal compared to the levels you’d get in regular coffee and other caffeinated beverages.

Decaf makes it easier for you to add coffee to your daily fluid intake alongside other caffeinated drinks. It can also work well with water as the only alternative drink.

Let’s say if your body reacts to caffeine, reduce its effects by enjoying caffeinated drinks in moderation, and you’re better off with decaf coffee than regular coffee.

Is 1,000 mg of Caffeine a Day Too Much?

To stay within the safe limit, where you don’t experience the mild diuretic effects, drink up to 400 mg per day. As your body’s caffeine level rises higher than the amount you eliminate, you may experience a change in system functions with every extra cup.

This change isn’t only worrying because of the additional times you have to pee. No! There are other effects like insomnia since your body’s sleep pattern changes when your brain can’t decide to shut down and rest. When you get to 1,000 mg, you’ll be drinking the 11th or 12th cup of the day, which means you must have skipped water and other hydrating foods.

Also, there’s anxiety as you’ll stay alert and adrenaline-pumped for hours, which can also cause fatigue. Your digestion may also suffer as the laxative effects change colon activity and hasten bowel movements. That’s not to scare you but to emphasize that high doses can change your whole body.

How Much Coffee Is 60 mg of Caffeine?

That’s the caffeine level in an average-sized cup of coffee, which is within the recommended limit of 400 mg per day. Therefore, you can take up to five cups. In such doses, you don’t have to worry about your hydration levels as there is room for more cups of water, fruits, and other food.

A 60-mg cup of coffee also lets you space your drinks, meaning the effects will also take a while to manifest. That is advantageous when your age or health condition hasten the diuretic effects of coffee, and you need to stay hydrated. It could also be the best amount to take in a day if you’re looking for a new favorite beverage by testing the effects of caffeinated drinks first.

Is Drinking Coffee Everyday Bad For You?

No, as the evidence we mentioned in one of the questions above proves that coffee is a good beverage as it hydrates your body as much as water.

What’s more, your body can metabolize it within hours. Since we are talking about everyday consumption, if it takes 12 hours to flush out a cup, you have 12 hours to stay caffeine-free before your next mug of coffee. During that time, you enjoy the benefits of caffeine we discussed earlier.

How Do You Flush Out Caffeine?

The level decreases in about six hours unless you take another cup of coffee and the metabolism starts again.

That being the case, waiting it out is the best solution unless the effects are severe. If they are, consider substituting water for coffee as you wait it out without experiencing some effects of caffeine like dark urine.

Physical exercise can also reduce fatigue by channeling the energy into something useful. It can also help you stay alert. Other healthy ways to wait it out include taking vegetables or fruits to replenish your system. Overall, if you have severe symptoms, don’t wait it out.

Avatar for Giada Nizzoli

Born in Italy but currently brewing from the UK, Giada is a highly-caffeinated coffee expert with a soft spot for espressos. She worked in cafés for years and has recently fallen in love with the practical Kalita Wave (just don’t tell her Italian moka pot!).

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