Water is essential for life. Water is the most important nutrient and the most abundant substance in the human body. Three quarters of the human body is made up of water; it is a major component in every cell. As simple as the three molecules (two hydrogen and one oxygen) that make up water are, they are necessary for so many basic physiological functions. Directly and indirectly, water is responsible for how the body regulates itself, produces energy, carries and delivers nutrients, filters toxins and many other vital processes of life. While a very straightforward concept, many people still do not give their body enough water or truly understand the benefits to the additives that go into water and other beverages.
The Facts
Water is needed to separate (by a process called hydrolysis) a phosphate group from adenosine triphosphate (ATP) or guanosine triphosphate (GTP) to get energy as illustrated by the following equations.
- ATP +H2O = Energy + ADP + Inorganic Phosphate
GTP +H2O = Energy + GDP + Inorganic Phosphate
All energy from food is used to generate ATP or GTP before its energy can be used by the human body, which makes water crucial to all energy usage by the human body. This is one of the reasons why drinking water can help you have more energy.
The Function
Water is the containing medium for electrolytes and all other ions throughout the human body.
**Being only 2% dehydrated can seriously degrade physical and mental functions.
**Being 15% dehydrated is likely to be lethal.
Water is also very important for removing toxins from the human body. The body has four major ways of removing toxins which are: perspiration, urination, bowels, and processing of toxins by the liver.
Water is also important to fitness and fat loss for several reasons including the following:
How Much To Drink
It is normally recommended to drink about 2 to 3 quarts of water per day. However, your size, activity level and the climate conditions you live in play an important role. As a general rule: if your urine is bright yellow, then you need to drink more water. Also, anyone who exercises nonstop for more than 1 hour should consider replacing electrolytes along with the water. This is to avoid hyponatremia (depleted sodium) or other forms of severe electrolyte depletion which can be dangerous.
Recommended daily amount (litres/day)
- Children: 1.3-1.7L
- Men: 3.7L
- Women: 2.7L
- Pregnant Women: 3.0L
- Lactating Women: 3.8L
Calculate Your Own Daily Water Requirement
The International Sports Medicine Institute recommends using this formula to calculate your specific needs.
You can also try this online Calculator for Daily Water Requirement.
Body Weight (in pounds)
Water Needed for Activity Level (50% for Sedentary People; 75% for Active Individuals
Add 16 fl oz. if you live in a dry climate
Add 16 fl oz. for strenuous exercise.
Example: 150 lbs. x 75% + 16 oz. + 16 oz. = 144.5 oz. per day.
if you divide by the number of hours you are awake, 144.5 oz/ 16 hrs. = 9 fl. oz per hour.
Negative Consequences of Over Ingestion
There are no maximum doses. Healthy and fully operating kidneys theoretically can filter up to 0.7 litres of water in one hour, that is almost 17 litres of water a day. However excessive ingestion of water and other liquids is extra work for the body. Signs of intoxication of water are hyponatriemya (decreased amount of natrium in blood) and rubdomiolysis (damage of muscularity – collapse of skeleton) what can cause acute incompetence of kidneys. Also it must be considered that average amount of water ingested by food is only 20% of recommended daily amount. The human brain is about 85% water and our bones are between 10 to 15% water.
The Truth About Water
The real truth is that water is one of the best cures for our most common ailments. The flip side of this is that there is very little money in selling water and for the most part it is free. Doctors almost never write a prescription for water and yet look what all it can treat: allergies, asthma, depression, high blood pressure, diabetes, headaches, chronic fatigue syndrome, colitis, alcohol dependency, lower back pain, neck pain, and on and on.
Don’t be fooled by considering the coffee, tea or soda pop that you drink as part of your water intake; these products are caffeinated producing the opposite effect on our bodies. Caffeine acts as a diuretic to our system and actually results in water reduction to our bodies. The same applies to drinks with alcohol. If you are drinking these items make sure you don’t count them as part of your eight glasses of water per day.
Drinking Water to Prevent Aging
Now is it just coincidental that disease and/or health problems dramatically increase as we get older? It has not been well documented, but there is a common generalized reduction in the amount of water in their intake in people as they age, which reduces their body water percentage. Some of the symptons that older people get lead them to reduce their water intake (such as high blood pressure). Loss of water in all tissues continues and is probably involved in many of the physical alterations associated with aging.
Strategies for Drinking More Water
4 Comments
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Liked the article – didn’t agree with everything but lots of interesting ideas and food for thought. Some contention in good spirit:
I’m no expert, but my understanding is that water requirements are largely derived from loss-replacement studies and tend to be misunderstood. As it turns out, a significant portion of water intake happens (or at least should happen) through food; depending where the loss-replacement data is coming from, it may be that it was never intended that people actually drink that much, just that their total moisture intake should roughly equal that amount – for the “average person” – in “average conditions.” Maybe we don’t need to drink as much as the new-school fitness experts are often saying?
Makes sense – as you point out, the water molecule is ubiquitous at the cellular level in all living organisms. After all, what we eat is (or used to be) alive. Not too jazzed about the drinking loads and loads of water thing – in a diet that includes lots of fresh fruits and veggies, that kind of thing shouldn’t be necessary unless you marathon in Mojave.
I liked that you mentioned that water intake depends on lots of variables, for example the temperature/humidity (not just because of perspiration; loss can also occur via evaporation from skin and especially mucous membranes if I remember correctly). It also depends on body mass – a variable that is often but not always mistakenly misinterpreted as a gender difference in the nutrition field. In my opinion, the body mass thing is also behind old people not drinking as much water; as with other nutrients, they simply need less because they are actually growing smaller as they age. I’m no expert, but old peoples’ kidneys might not be up to filtering the gargantuan amounts of beverages that young sporty-types consume these days from their very large Nalgene bottles.
All that said, the kind of American diet based on lots of dry grains (breads, chips, crackers, cookies, bagels, etc., etc.) is of course not going to cut it in terms of water intake. I really like your advice to check pee color; it is a cheap (and gross) but pretty effective way to get a customized assessment of water intake, and though not foolproof, is much better advice than the typical rule-of-thumb liter requirements – which, again, are based on loss-replacement studies taking into account body mass.
I’ve often heard from exercise and nutrition specialists to “not wait until you’re thirsty” to drink. It never made much sense to me – I can’t believe that somehow it’s better to trust overconsumption over one’s own biological thirst mechanism whose very nature is to prevent you from becoming dangerously dehydrated. This advice has the spirit of “better safe than sorry,” which I guess is fine – my problem is that overconsumption of nutrients is consistently advocated by exercise and nutrition specialists, from water to vitamins to just about anything. While thinkers of the day are quick to blame the U.S.’s obesity issue on things like fast food proliferation or a declining food quality due to agricultural centralization/simplification, perhaps the issue stems partially from the fact that our experts are always telling us to eat and drink more than we need. Definitely not saying that water is making anyone fat – just bringing up the point that balance, moderation, and common sense so often lose out over trends, miracle solutions, and “better-safe-than-sorry,” and that this is sort of a philosophical thing that perhaps expert types might consider with fruitful result.
From a losing weight perspective, water has some importance I think. I vaguely recall water being a catalyst/ingredient in beta-oxidation; doesn’t hurt to have around for eliminating the resulting acetone that’ll be floating around the place, either. Some weight loss advice is voodoo; actually, I don’t knock that, because some voodoo seems to actually work. Water is one of those things that doesn’t seem to hurt much as long as you don’t totally overdo it, so even though I think that overconsumption of water is weird advice for people happy with their weight and diet, it might be great advice for people looking to lose weight or alter their diet. For that reason, I think the article was a great one to include in the blog. It seems to have some potential perhaps for being a weight loss tool in keeping with the site mission.
One last contention is that clean freshwater is neither cheap nor easy to get from a global perspective. I’m no expert, but my guess is that percentage-wise, most unprepped earth water fit for human intake is trapped either in the cellular structure of food or trapped inside giant blocks of ice at the poles. Nice clean water is actually a bit of a luxury from what I understand, and I’m very grateful we have it here in the U.S. in ample amounts; might not always be the case.
Keep the interesting articles coming! Any chance for citations in future articles?
PS please forgive the length – I know the site founder from HS and promised I’d leave a thoughtful post to contribute to discussion on the site. PSS glad you didn’t mention bisphenol-A
I think both this article and the long comment are both very insightful. I am glad you mentioned that over consumption isnt the way to go either. I’d like to comment that utilizing our thirst to gauge how much we should drink may not be too reliable (such as people, like myself, who ends up eating too much because my taste buds & growling stomach are telling me I want to eat). I consider drinking coffee or tea (diuretic) is a way to get water into my system. I understand that both are diuretics and I just wonder if I am depriving my body from water if I drink only tea? I would suppose the answer is yes, but I havent taken into consideration the amount of water I get from other foods. What do you think?
Thank you both for the insight on this issue. There is a lot of controversy about the topics surrounding hydration and water consumption. My goals as a writer are to provide information to readers that is current and interesting. I am glad that there is an active audience out there that is challenging the articles that I put out there.
In regard to the first comment, thank you for your in depth response. You make a very good point about the water replacement theory through food consumption only. We are very fortunate in this country to have access to clean, pure water, but I disagree that food alone is enough to fulfill all of the body’s metabolic requirements. “Food” can mean many different things to many different people. I don’t think I am over exaggerating when I say that the average American diet does not include the amount of fruits and vegetables high in water content that is necessary for the body’s water needs. Having food heavy in carbohydrates or dry foods such as a bag of chips or pastas are common, but require water to break down for digestion. For those of us that are health conscious and looking to get water from food sources only, I would say, proceed with caution, and monitor your urine.
Here is some more information about coffee and tea vs. water consumption. A cup of coffee has about 200mg of caffeine. A cup of tea has quite a bit less (40-100mg), depending on the strength of the tea. (I pulled these numbers from the Tea Council and Association of the US.) However, the general consensus as of late is that, despite the caffeine, these beverages still count towards your fluid intake for the day. The reason is that, although caffeine is a diuretic, the amount in a strong cup of coffee or tea is not enough to dehydrate, and there will still be a net gain of fluid. I still want to emphasize the fact that for the best hydration for your body, choose fluids that do not contain caffeine. It is my bias to say this, however, I am definitely guilty of consuming my share of caffeinated beverages.
Although coffee and tea may be equal in their hydration factor, tea still gets the upper hand for your health. A recent sutdy in the European Journal of Clinical Nutrition says that drinking tea is not only as good as drinking water, but possibly better, as it may carry extra health benefits in protecting against heart disease and some cancers. We can also look to other cultures where they do not enjoy the luxury of purified water, where they do drink tea in place of water.
Drinks with caffeine can be good to suppress appetite and help with snacking urges. Having an afternoon or evening cup of tea/coffee is calorie free (as long as you don’t add anything to your cup). Green or herbal teas are a great choice because of the extra health benefits.
In writing this article I did not really want to get carried away with talking about when exactly to be consuming your fluids in regard to eating. There is a lot of debate over this topic as well, as some people think that drinking water during or with meals can dilute stomach acids and slow digestion. In cohesion with this thought, researchers have begun to recommend drinking fluids 1-2 hours after eating solid foods to avoid making your stomach a “water balloon.” (This is useful to make you feel full, especially if you are looking to lose weight.)
Keep the comments coming!
3.7L for men daily? Are you for real? i don’t get that in three days.
I do drink juice though, does that count?
Ryan