I have heard a lot of “how much water should you drink a day” questions over the years. I have also heard several different answers to that question. I am sure you have heard that you need to drink 8-10 glasses of water per day to be healthy … if you want to lose weight then you should drink more. The reality is that this might be true for some but it might not be for others. The amount of water needed is different for every individual.
All this talk about water is making me thirsty …
yikes, I’m already dehydrated!
You have probably heard that if you are thirsty then you are already dehydrated. Another inaccurate statement! More about that below. Don’t get me wrong, water is very important.
In this post I would like to answer the question regarding how much water should you drink a day to lose weight and to be healthy. In reality, the amount you drink should not change whether you are trying to lose weight or not. Just drink enough to be healthy either way.
How Much Water Should You Drink A Day?
The most common answer of 8-10 glasses a day is not a bad answer. The real problem with it is that it is not a one-size-fits-all question.
A good goal is to drink 1 ounce for every half pound you weigh. So if you weigh 180 lbs you should drink 90 ounces of water each day … as a general rule. In reality your body needs more water than this per day. Fortunately, not all of our water consumption needs to come from drinking it.
The amount of H20 you get per day (another general rule) should be about 125 ounces a day for men and about 90 ounces a day for women. This does not mean that you need to drink this much water. Our food is made up greatly of water.
Here are a few examples of the amount of water that is contained in the food we eat to help you understand that the answer to how much water you should drink a day can vary depending upon what types of food you are eating.
| Food |
Water
|
| Lettuce |
95%
|
| Watermelon |
92%
|
| Broccoli |
91%
|
| Grapefruit |
91%
|
| Carrot |
87%
|
| Yogurt |
85%
|
| Apple |
84%
|
With this in mind, we can see that the more (healthy) food we eat, the less we need to drink.
Also, the former 8 glasses of 8 ounces is officially believed to be exaggerated. In conjunction with this study from Heinz Valtin called “Drink at least eight glasses of water a day” Really? Is there scientific evidence for “8 × 8″?, the Institute of Medicine concluded that the 8/8 theory is not realistic. They even suggest that letting our bodies determine when we need to drink water is sufficient.
“… vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide ..”
What about the theory that if we are thirsty it’s already too late? This is more of a theory than a fact. In an interesting study about water consumption when related to being thirsty, the analysts found that the human body is not sending signals that it already is dehydrated when you get the urge to drink.
“… during free access to water humans become thirsty and drink before body fluid deficits develop … provide evidence for anticipatory thirst and drinking in man.”
So yes, our bodies are smart enough to tell us to drink BEFORE we are dehydrated … who would have thought!
Variables In How Much Water You Need
Since the above formula is still a general, rule of thumb, there are some variables that may increase or decrease the amount of water you need each day.
One of the most significant factors is the amount of exercise you do. When you exercise or engage in any other activity that makes you sweat you need to drink more water. You should drink water a couple of hours before a workout, right before a workout and then while you’re working out. After you workout you should drink more water. Do you see a pattern? It is not just about how much water you should drink a day, it is also about when you drink it and how much your body is using and/or losing.
Why You Need So Much Water Each Day
Every cell in our body requires water to function properly. Our bodies are made up of anywhere from 55-78% water depending on our size. Generally, about 2/3 of our bodies are made up of water. Here are some approximate values.
- Brain – 90%
- Blood – 83%
- Muscle – 75%
- Bone – 22%
The water in our bodies has many functions. From helping our metabolism to protecting our vital organs, water is essential element to life.
Really, how much water should you drink a day?
What many fail to realize though is that we get water in our food, in our coffee, in our tea … and even in our beer. So next time someone asks you how much water you should drink a day you can tell them … whatever you feel like!
Nice advice on how much water you should drink. I tend to avoid keeping track of how much I’m drinking and let my thirst be my guide as you say. I try to have 8 ounces right when I wake up because I always feel dehydrated.
Seems simple enough, but in the end that is a solid approach.
I usually force a full glass of water down my throat in the morning (along with a few of my daily vitamins & pills) but from then on I just make sure to have a glass of water on my desk for whenever I get thirsty.
Kevin,
I know I probably don’t drink as much water as I should every day, but on the most part I always have a glass first thing in the morning and last thing at night. Yet, since my diet does rely on pretty heavy veggie format I never feel dehydrated. I prefer a cold glass of water with every meal, and will always make sure I’m sufficiently hydrated before starting a workout.
-Mitchell
That’s a good point; we get a lot of water from our food. Veggies and fruit have the most so the more “good” food you eat the less water you need to drink.
This is a great summation of the issues available, good job!
The weird thing about the thirst issue is that I’ve found that it gets better if you actually give it water!
What I mean is that if you have a good slug of water when you first get up, your body seems to recognize thirst instead of hunger. I have very good feedback from clients about this little tactic. It seems that some peoples bodies need to be re-calibrated to recognize thirst and not mix it up with hunger!
I should add that I go through not less than 2 litres of water a day, and have no idea how much this relates to ounces of water. I sure know that I go through more of it when I exercise, and even more when I exercise fasted (as I tend to do 4x each week).
My 2c,
Hey George, 2 litres equates to about 67.6 ounces. No, I didn’t know that, I looked it up because I was curious.
I hear you though, my water intake changes drastically depending upon my day. My fasting days do seem like I get more water in as it helps to curb appetite a bit.