How Much Water Should I Drink a Day? The Truth Behind Water Consumption
Here’s a common question: How much water should I drink a day?
Hmmm. Well, we’ve all heard the same cookie-cutter advice…
You need to drink 8 glasses of water per day.
I mean, sure, water is important. But is it that important? Do you really need that much of it?
Well, since I’m naturally curious and I have some not-so-serious trust issues, I figured I would do some digging around and test things out for myself to finally uncover the truth behind water consumption.
Let’s just say the findings were beyond intriguing…
Before I get into the details, let me give you a little background about how all this got started.
As often is the case, the spark came from a book (I love books) and this time it’s one of my favorites – the Primal Blueprint by Mark Scisson. In the book, Mark spends some time talking about hydration and the excessive attention it’s gotten over the years.
But perhaps it’s attention well deserved.
At the same time, I was laser focused on consuming more water than most could carry. After all, I’ve always been told (as an athlete and health nut) that more water means better health. So when I happened to read that this may not necessarily be true (according to Scisson), it sparked something inside of me to dig a little deeper and get to the truth.
So I did
some a lot of research and came up with some interesting facts.
Water is everywhere. I mean think about it. Everything is composed of water. Our planet is 70% water. Our bodies are roughly 60% water. Many of the things that we consider to be solid are actually mostly composed of water.
Plus the list of benefits of consuming water are through the roof.
Healthier skin. Better lubrication of joints and muscles. Better regulation of body temperature. Detoxification. More energy and alertness. Better transportation of nutrients and oxygen to cells (plus better absorption of these nutrients). Improved metabolism.
I could go on forever.
But the question isn’t whether drinking water is beneficial. You’d be a fool to think it’s not. The real question is how much water is necessary. How much water should I drink a day? Where does the diminishing effect come into play?
The 8 by 8 Guidelines
The 8 by 8 rule simply states: drink eight 8-ounce glasses of water per day (64 ounces of water total). For proponents of the metric system, this is roughly 1.9L of water per day.
But where exactly did the 8 by 8 rule come from? That’s actually a very good question and one very few people will be able to answer. Nobody really knows much about the origins of this ideology. Even many of the top nutritionists in the world can’t tell you where it comes from and they’ve written books on the topic of water!
Perhaps it’s just a convenient reference point. Professor Heinz Valtin from Dartmouth Medical School who specialized in kidney research spent over 40 years studying the systems that keep water in our bodies balanced says that the 8 by 8 rule actually originated from a misunderstanding. Back in 1945, the Food and Nutrition Board (now part of the National Academy of Science’s Institute of Medicine) suggested that a person consume one millimeter of water for each calorie of food. So, for a typical 1900 calorie per day diet, this comes out to 1900 milliliters of water per day, or roughly 64 ounces.
Dr. Margaret McCartney speculates that this ‘guideline’ is a complete myth that is being propagated by bottled water companies who are in the interest of sucking in profits.
“There are many organizations with vested interests who would like to tell doctors and patients what to do. We should just say no.” – Dr. Margaret McCartney [ref]
She gives an interesting example. There is a new international health initiative called “Hydration for Health,” which promotes drinking more water for a healthier lifestyle. Guess who it’s sponsored by? You guessed it, Danone – a company that markets the Evian and Volvic bottled water brands.
Next up, we have the Institute of Medicine which has basically decided to put the 8 by 8 rule on steroids. They have determined that an adequate intake for men is roughly around 3.7L and for women around 2.7L (even more if you’re pregnant). That’s a lot of water my friends.
But drinking more water is good, right?
Well, according to a study published in the British Medical Journal, drinking eight glasses (or more) of water does not deliver on the promised health benefits. In fact, drinking too much water can have detrimental effects on your health, including a condition known as hyponatremia (a low-blood-sodium condition). This is a serious (and occasionally fatal) condition that results when excessive water consumption per day causes sodium levels in the bloodstream to become too diluted.
“If you’re drinking excessively, if you’re drinking beyond thirst, if you’re drinking beyond comfort, your kidneys are actually having to work very, very hard.” – Dr. Margaret McCartney [ref]
So how much water should you drink a day, you ask?
Well, it depends on a few factors.
“Water requirements depend so much on outside temperature, activity levels and other factors that there isn’t one rule that fits everybody,” says Barbara Rolls, a professor of nutrition sciences at Pennsylvania State University.
Indeed this is true. If you exercise or engage in sweat-inducing activities, you need more water. If you live in areas that are more hot or humid throughout the year, you need more water. If you’re sick (fever, vomiting, diarrhea), you need more water. If you’re pregnant, you need more water.
But even with all these factors and our wide variation in water intake, the human body is very capable of maintaining normal blood concentration. Your kidneys and endocrine system work very efficiently to promote optimum fluid levels in your bloodstream.
Dr. Valtin and other experts have found that if your blood becomes concentrated by about two percent, your thirst mechanism becomes activated and you’ll feel thirsty. Once your blood becomes concentrated by five percent, the symptoms of dehydration become present.
What about food and other drinks?
Most people don’t realize how much fluid they obtain from the food that they eat. On average, food provides about 20 percent of our total water intake [ref]. Chicken is over 50 percent water. Pizza is 50 percent water. Raw milk is 90 percent water.
According to this article, there are no restrictions on the maximum amount of water a food can contain (although it must be on the label).
Remember the whole profit ordeal? It plays a factor here too.
Apart from the natural water in foods, manufacturers tend to add water to (cheap) foods to increase their weight so they can be sold for more profit.
“Consumers are being duped by manufacturers who are adding water to bulk up the size and weight of produce, and what’s worse, it isn’t possible to work out from the label how much water has been added.” – Ian Tokelove of the Food Commission.
What about checking out your urine?
We’ve all been told to take a look at the stream of urine that comes from our you-know-what. If it’s dark, you need to drink more water. If it’s clear, you’re good. Right?
Well, according to Dr. Valtin, there is no validity ot the idea that your urine needs to be clear to indicate adequate hydration.
So what do we do?
Some say that the best advice is to let your thirst be your guide.
Mark Scisson, author of Primal Blueprint, says:
“I recommend consuming a sensible amount of fluid each day, using your thirst as a guide to maintain optimum hydration. Sometimes this might be eight glasses of water, sometimes much less than half that.” – Mark Scisson
Some studies don’t agree.
Some say this isn’t effective because apparently so many people are chronically dehydrated that they no longer recognize their body’s signal for water.
But, of course, there are other studies (some done by Dr. Barbara Rolls) that show no evidence of people being chronically dehydrated.
I hope you’re confused as I am.
In an effort to set things right (at least for myself) and determine how much water I need to drink per day, I figured it was time to do a little test…
The 30 Day Hydration Test
With all this confusion, I thought it would be best to do a little of my own testing. I put together a simple little test which I like to call the 30 day hydration test. It didn’t require any crazy laboratory equipment, test specimens, or expensive tools. Actually, it barely required anything at all.
All I wanted to do was see if my body reacted differently to when I drank a lot of water compared to when I drank very little water over a (somewhat longer) period of time.
Here’s how it worked.
For the first 15 days of the test, I drank the Institute of Medicine’s recommended 3.7L of water per day (it’s a lot of water). For the last 15 days of the test, I let my thirst guide me – I only drank when I felt thirsty.
So what happened?
First 15 Days: 3.7L of water per day
For the first 15 days, it literally felt like I was drinking water every five minutes. It literally took effort to consume nearly 4 litres of water every single day.
But how did I feel?
Actually, I felt amazing. I definitely felt more energized and alert. My thoughts were much clearer and my body felt healthier (hard to explain the feeling really).
My productivity definitely suffered as I was running to the bathroom anywhere from five to ten times per day. My urine was so transparent that it could be mistaken for water (sorry no pictures included).
Last 15 Days: Obey Your Thirst!
For the last 15 days, I let my thirst be my guide. I only drank when I felt like drinking. If I felt any signs of dehydration, I would drink a glass of water. The amount I drank was different from day to day (as expected) and ranged anywhere from one to two litres.
So how did I feel?
Surprisingly, no different from the first 15 days. I still felt mentally alert. I still felt energized. Of course, my visits to the bathroom decreased by more than 50% and my urine started to darken, but nothing else seemed to change.
The Final Word
Now I know this is a very weak test. It’s possible that the effects of drinking 4L of water in the first 15 days transferred to the last 15 days. But I did my best to keep all other variables (exercise, food consumption, my environment) as consistent as possible to ensure any noted differences were dictated by the change in water consumption.
So how can you use all of this information?
There definitely seem to be a lot of opposing studies and ideas on the consumption of water (seems to be a common theme in the field of nutrition).
We all know that water is vital for optimal body function.
But it’s important to understand that it’s possible that your current drinking habits might be dictated by the slogans crafted by large bottled water corporations rather than your own body signals.
It’s important to understand that there is such a thing as too much water and that constant excess consumption can put a lot of stress on the kidneys. It’s important to understand that a good fifth of your overall fluid consumption comes from your (solid) food.
So how much water should you drink a day?
In my opinion, and based on the little test I conducted, you should let your thirst be your guide. Your body is an incredible machine. Maybe it’s best that we let it make these kinds of decisions for us.
What are your thoughts on water consumption? Please share them in the comments below. I’d love to know what you think.