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If Beer is a Liquid, How Can It Possibly Dehydrate Me?

It’s not the beer per se, it’s all those trips to the bathroom it inspires that’s the culprit

It would be a gross oversimplification to say that the relationship between the human body and beer is as simple as love-hate. The range of outcomes on the spectrum of pleasure to misery is so vast, so dependent on time, location and alcohol quantity and so linked to personal physiology and psychology, that you might feel like you need two PhDs and an MD just to enjoy a Heineken responsibly. 

To that end, one of the things I’ve long yearned to grasp is the exact relationship between beer and your bladder — namely, whether or not it’s the properties of the beer that prompt you to piss, and whether or not that subsequent urination is one of the reasons why you might feel dehydrated after you’ve spent an evening sampling everything on tap at your local craft brewery.

So is it the alcohol that’s responsible or not?

You can 100 percent blame it on the alcohol.

The idea that alcohol has a dehydrating effect on the human body has not only been a presumed fact for centuries, but it was also among the reasons cited in the push for temperance and the ultimate prohibition of alcohol during the 1800s and early 1900s. In an issue of The York Daily from February 1900, Dr. Frederick D’Evelyn reported on his experimentation on potatoes and onions with alcohol, and said that the deterioration found in the cells of the vegetables was “similar to that found in the corpuscles of a habitual drunkard.” He also stated that it was the dehydrating power of alcohol that makes it so destructive.

In 1916, temperance advocate Marie Brehm was quoted in The News Journal of Wilmington, Delaware as saying that alcohol is “a dehydrating protoplasmic poison,” and further referred to it as “a beverage injurious to the human organism.”

While both time and reliable scientific study have been kinder to alcohol than these early-20th-century impressions might have suggested they would be, the assertion that alcohol is dehydrating is correct. This is because alcohol is classified as a diuretic, meaning it will accomplish the seemingly magical task of causing you to urinate out more liquid than the quantity of alcohol you originally imbibed.

Why does this dehydration happen?

Brace yourself for an extraordinary hockey analogy.

Your body contains an anti-diuretic hormone called vasopressin, which for our purposes is best anologized as a hockey goaltender. When you drink a delicious Scotch Ale, Bourbon Barrel Stout or Bavarian Trippel, it can be the equivalent of sending your brain a signal to pull the goalie, thereby leaving the net wide open. When this happens, your kidneys light up by thinking about how many shots they can fire at the proverbial net. As a result, they shoot water straight to your bladder, and your bladder ushers you straight to the bathroom. Once you reach the bathroom, your body will expel urine commensurate with the amount of alcohol you drank, with 250 milliliters of alcohol instigating the release of between 800 and 1,000 milliliters of water from your system. 

I noticed that all the beers you named were pretty high in alcohol content. Do you have a special fondness for heavy beers, and does all beer dehydrate you?

As for your first question, that’s between me and the bartender. As for your second question, this is where things get trickier, but not that much trickier.

Studies have shown that the diuretic effects of alcohol only showcase themselves when you’ve consumed drinks with a relatively high alcohol content. So if you opt for light beers as opposed to heavier, more caloric and (who are we kidding?) infinitely more tasty brews available on tap, it will reduce the likelihood that you’ll be spotted sipping on a Monster Rehab drink as you suffer your way through a hangover.

That sounds brutal, but is there any way beer could ever hydrate me?

Technically, yes. Scientific studies have unearthed evidence that beers containing alcohol content of 4 percent or less can have “a negligible diuretic effect,” which would suggest that your beer can be hydrating as long as you keep its alcohol content exceedingly low.

Let’s be honest, though: Even the lightest of the awful and impotable light beers all technically have ABV values that exceed 4 percent. You probably don’t like them either, because pretty much nobody likes them. You’re drinking beer because of how awesome it makes you feel, how side-splittingly funny it makes you think you are and how much more entertaining it seems to make everyone else. 

The price you pay in return is that those suds will be sure to take the piss right out of you.

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