Water: The Forgotten Nutrient
by Marlene Harris, NSCA-CSCS, NASM-CES
Given the onset of warmer weather, the importance of water, dehydration, and recommended intakes makes for timely topics. Most people don’t drink nearly enough water, and even mild dehydration can cause impairment along a number of dimensions. Read on for more details on this very important nutrient!
What did that say? Water, a “nutrient”? Yes indeed! That’s what my nutrition text says (the one that was assigned for a nutrition class I took at MCC). In fact, this beefy 720 page text devoted an entire chapter to the topic titled; “Water and the Major Minerals”-the minerals being the elements that float around in the water in your body.
The first sentence in the chapter reads; “Water is an essential nutrient, more important to life than any of the others.” The second sentence says; “The body needs more water each day than any other nutrient.” As evidence to the point, did you know that you can survive a matter of weeks without food, but only a few days without water? Below is a short list of reasons that water is so vitally important to us:
1). It carries nutrients and waste products throughout your body.
2). It maintains the structure of various cells and molecules in your body.
3). It’s involved in a number of metabolic reactions.
4). It serves as a solvent so that minerals, vitamins, proteins, and other nutrients can carry out metabolic activities.
5). Serves as a lubricant to joints, the spinal cord, and within your eyes, among other locations.
6). Assists in the regulation of your body temperature.
7). Maintains proper blood volume. (I’ll return to the importance of this later in the discussion).
One of the most important, and confusing aspects of water intake is that your thirst for it actually lags behind your body’s need. You may have heard and dismissed this idea before, but it’s true that by the time you become thirsty, you’re already mildly dehydrated. Further, the signal can be confusing; we can think we’re hungry, but we’re actually thirsty!
You can become dehydrated via a number of ways, and these can all combine to work against you; sweating is a more obvious form of water loss, but your body loses water via other functions such as waste excretion (solid and liquid, if you catch my drift), and through a more subtle form-in vapor from your lungs as you breathe.
Here’s a breakout on the various levels of dehydration and the consequences. Note how little water needs to be lost before physical and even psychological symptoms appear!
% Body Weight Lost Symptoms
1-2% Thirst, fatigue, weakness, vague discomfort, loss of appetite.
3-4% Impaired physical performance, dry mouth, flushed skin, impatience, apathy.
5-6% Difficulty concentrating, headache, irritability, sleepiness, impaired body temp. regulation, increased respiration and heart rate.
7-10% Dizziness, muscle spasms/cramps, loss of balance, delirium, and if continued, exhaustion, collapse, and coma.
To give you an idea about how much (how little, actually) water needs to be lost in order for these symptoms to manifest, here’s a couple of examples:
For a 210 lb. guy: a 1-2% water loss is only 2.1-4.2 pounds! It you’re among those who sweat a lot while working out or doing other tasks, you’re going to want to pay very close attention to your water intake and be sure to keep your intake generous and frequent!
Let’s jump to the 5-6% loss range: this is only 10.5-12.6 pounds of water loss. This may sound like a lot, but when you consider how much you can soak your t-shirt and/or towel at the gym, while doing heavy yard work for a few hours, playing game of touch football or other outdoor recreation, these losses are not hard to imagine!
For woman, the losses needed to provoke symptoms are even smaller. Women may sweat somewhat less than men, they also have less lean body mass (naturally), therefore carry less water weight than the guys right out of the gate (monthly considerations aside), so this can compound the problem.
For a 150 lb. woman, a 1-2% water loss is only 1.5-3 pounds! As a side note, I can pour that out doing my brutal little kettlebell circuit in ½ hour! For the 5-6% range, this represents a loss of only 7.5-9 pounds of water. This makes staying well hydrated just as important for the gals!
Earlier I mentioned returning to discussion of blood volume, or the amount of fluid that comprises your blood. As you lose water, your blood volume drops, which makes your blood more concentrated (i.e., thicker, as all the blood cells are floating in less fluid). This makes it harder to move through the network of veins and arteries that feed your organs and muscles. Among other things, this means that your heart will have to work harder to drive your blood through your body. Also, your blood vessels will constrict in response to lessened blood volume. Both of these conditions can drive up blood pressure-not a good situation for those of you who already have high blood pressure and/or a heart condition. This represents an unnecessary and completely avoidable stress on your body and health, remedied by your simple efforts to drink more water and stay hydrated! Additionally, as we age, we need to be more vigilant about our water intake the following reasons:
1). Our sense of thirst will be even slower to kick in than for those who are younger.
2). We carry even less water due to decreased lean body mass than those who are younger--which is yet another good reason to strength train to keep building your muscles, now isn’t it? J
Now that you’re convinced that drinking sufficient water is an important daily goal, you’re probably wondering how much is sufficient. Here are some basic guidelines:
Men: 3.7 liters per day, which translates to about 1 gallon, which is about 16 cups (or 128 ounces).
Women: 2.7 liters per day, which translates into about ¾ of a gallon, which is about 12 cups, (or about 96 ounces).
Now, the above are just general averages. If you live in a warmer climate, you’ll need to up the ante. Further, if you are vigorously physically active, add even more. For us here in the desert, and who are (hopefully…) working out regularly, putting in a good sweatin’ effort, the above recommendations should be considered bare minimums. Given that most people don’t take in anywhere near the above recommendations and it’s very difficult to “over-hydrate” here in the low humidity of the desert, be liberal in ramping up your intake of this most important nutrient!
Reference: Understanding Nutrition; Whitney et. al. 2008
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