Caffeine and Dehydration
The Health Connection
by Merlin Hearn

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man drinking coffeeIs there a caffeine and dehydration link?

For many years, health advocates have speculated that caffeine and dehydration are closely linked. 

The idea is that because caffeine is a known diuretic, it causes excess water loss in the body and thus robs the body of essential electrolytes. 

I am writing this to address whether or not this is true and to help you determine the impact of caffeine on your health. 

As I write this, I’ve been sitting in a coffee shop for a few hours and I am on my third cup of tea.

After several trips to the bathroom, I can say pretty comfortably that caffeine feels like a diuretic to me. 

Caffeine Is a Mild Diuretic

Yet my experience seems contrary to the experts at Beverage Institute for Health and Wellness (BIHW). According to the BIHW, if you are a regular caffeine drinker, your body has developed immunity to the diuretic attributes of caffeine.

Dr. Grandjean, when interviewed by the BIHW, had this to say:

“The human body develops a tolerance to caffeine after about three to five days of regular use.

"This is why, even though caffeine is a weak diuretic, drinking caffeinated beverages is not detrimental to the hydration status of those who regularly consume them. 

“Our bodies are very good at making adjustments to maintain homeostasis.

Since water is so critical for life, it only makes sense that our bodies can negate the mild diuretic effect of caffeine. Research now solidly substantiates that this adjustment does, in fact, occur.” 

Long-Term Effects of Diuretics

Our bodies can “negate the mild diuretic effect of caffeine”?  Possibly, but ONLY if we are drinking more than enough water each day!  

Yes, our bodies are ingenious at drought management—but I don’t believe our bodies can fully negate the bad effects.  

Perhaps we won’t notice the short-term effects, but the long-term effects of chronic dehydration are significant to overall health and wellness.

While I don’t question the science and testing that Grandjean and her peers have done, I do have to question what constitutes a “regular” caffeine drinker. 

I have been drinking tea and coffee regularly every day for the past two months, about two to three cups a day. And yet, I still feel the diuretic effects of caffeine and have to urinate more frequently than usual while drinking it. 

Caffeine Increases Metabolism

Another secondary effect of caffeine on the body is that it increases metabolism, which increases body temperature and uses up more water since everything is happening faster than usual.  

When consuming caffeine, your body is in overdrive and has to use more water to fuel it.

Unless you are also drinking more water along with your coffee, tea, or sodas, where is your body going to get the water it needs?  

According to Nancy Hearn, certified health and nutrition consultant, the body will pull the needed water first from the colon (causing problems with elimination and other gastrointestinal issues) and then from other critical areas of the body.

Electrolyte Imbalance

Then there is the simple fact that caffeine is a foreign substance (i.e., toxin) in your body, and much like alcohol or sugar, your kidneys will try to flush it out of your system. This will most likely cause you to urinate more frequently.

Add that to the fact that caffeine increases the excretion of sodium (salt) and other key minerals from the body and can thus deprive you of  much-needed electrolytes. 


In spite of what some experts say, I still believe caffeine and dehydration are closely linked, even for those of us who regularly consume it.

I know that I need to drink more water than usual when I drink coffee, tea, or sodas to help counteract the long-term diuretic effects of caffeine. 

However, I also believe there are other benefits of drinking coffee and herbal tea, but that is not the topic of this article . . .

Reference Caffeine and Dehydration

Return from Caffeine and Dehydration to Dehydration Effects

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