I can remember it like it was yesterday: It was the week of freshman band camp, and our band director Mr. Sheckler was lecturing us as to why we shouldn’t be drinking soda before reluctantly dragging ourselves onto the practice field. “If you’re tired out on the field and you drink pop, it’s not going to help,” he declared. “All it’s going to do is dehydrate you, send you running to the bathroom and then you’ll be even thirstier than you were before. That’s why you need to make sure you only bring water with you.”
When you’re forced to listen to statements like this from adults in authority during your formative years, it would justifiably lead you to suspect that the result of adding anything enjoyable to water somehow renders that water worthless, if not deleterious, from a hydration standpoint. It certainly did for me. But looking back, I’m not sure how smart it was to put all of my trust in a high school band director’s understanding of science.
What is the deal with soda in particular? Does the water within it not count toward hydration?
If you’re guessing that it wouldn’t, your belief is probably attributable to the fact that soda is defined by the carbonation of its water, and often contains sugar and caffeine, although neither of those ingredients is essential for it to be an acceptable soft drink.
As vilified as carbonated water has been — the accusations against it include that it reduces the calcium in bones (false), causes tooth decay (also false) or may make you gain weight (mostly false; it might make you slightly hungrier than usual) — the act of dissolving carbon dioxide gas in water at the low levels required to manufacture carbonated beverages does nothing harmful to the body beyond making your burp. It certainly doesn’t turn it into a dehydrating beverage.
Now, there is evidence that sugar in high quantities can be dehydrating, primarily to people suffering from diabetes. However, there’s also evidence that sugar can help transport water and sodium across the intestinal barrier, creating a scenario through which sugar actually aids the act of hydration. Either way, if you have a condition that causes sugar to act as a potential hydration hazard, you can just consume a sugar-free soft drink.
As for the caffeine, we have no choice other than to accept the scientific evidence that caffeine is a mild diuretic. Yet this doesn’t exactly mean what you think it means. If the soda you’re drinking contains caffeine, it will prompt you to urinate more quickly and with greater urgency than you otherwise might. But that doesn’t necessarily make soda dehydrating in the technical sense of the word, because it doesn’t cause more water to be drawn out of the body than you’ve put into it. The definition of dehydration involves causing the body to lose a large amount of water, kind of like how the sun causes you to perspire, and the sweat departs with no liquids being replaced. Soda doesn’t cause the body to lose more fluids than it replaces, so the body technically loses nothing. Even Steven!
What’s an example of a liquid that’s truly dehydrating?
Beer is dehydrating due to the alcohol contained within it. The good news is, it’s probably not as bad for you as you think it is. The bad news is, from a hydration standpoint, beer is still going to be rougher than pretty much anything else you can name that doesn’t have alcohol in it.
The quick and dirty math suggests that 10 grams of alcohol induces your body to produce 100 milliliters of urine, which is slightly less than 3.5 ounces. An average drink contains 14 grams of alcohol whether it’s 1.5 ounces of a standard spirit, 5 ounces of wine or 12 ounces of beer. Fascinatingly then, downing a shot of whiskey will have the bizarre effect of causing you to piss out more urine than alcohol you drank. This, though, is drastically attenuated with respect to beer, as the alcohol content of a typical beer will leave you with the overwhelming majority of the water content of your beer still in your system. Obviously you’d prefer to hold on to more of those fluids, but you’re probably prioritizing getting hammered, so it is what it is.
This phenomenon happens primarily because alcohol prevents your body from releasing vasopressin, which is an antidiuretic hormone. Without vasopressin’s nagging presence encouraging you to hold onto your internal water supply, your body lets loose and sheds some of the watery reserves it was clinging to. But again, relatively speaking, beer is your best boozy choice on this count.
What about Gatorade?
Aside from their advertised role of replacing the water lost through exercise, sports drinks like Gatorade also help to replenish the electrolytes associated with hydration. The human body requires certain levels of electrolytes in order to easily maintain its fluid balance inside and outside of its cells. This is why hospitals include electrolyte solutions when administering oral rehydration therapy. In the absence of adequate minerals, the body won’t return to optimal condition — and certainly not as quickly as it otherwise could if those minerals were present.
However, unless you’ve been engaged in prolonged activities that have resulted in your body’s levels of essential minerals taking a plunge — e.g., long rounds of exercise, or problematic medical episodes like diarrhea and vomiting — a sodium-infused sports drink isn’t going to rehydrate you any faster than ordinary water… or a Diet Mountain Dew! This is because the minerals required to optimize your hydration are already stationed at their posts; they’re simply awaiting the return of fresh water.
So, no, there’s nothing inherently wrong with the water contained within your sports drink, but there’s also nothing all that special about it that’s enabling it to rapidly rehydrate you unless you’ve spent the last 90 minutes rowing with the members of the Harvard crew team.
Here’s the beauty of all this: Each of the aforementioned beverages can count in some way toward the recommended intake of 64 ounces of water per day, although a beer may set you back ever so slightly. Which means the next time a know-it-all in a position of power oversteps their scientific authority and tries to tell you not to drink that delicious Coke Zero, smile and chug deeply, confident that the only one missing out is them.