Hydration and Dehydration

By Doctari
Last edited 24 June 2005

Summer is almost upon us, and with it increased heat, even on the “long dark tunnel” that is the AT in many sections. There is of course always the possibility of water shortage, even in winter. Which brings up the issue of dehydration.

What is dehydration?
Basically Dehydration is a condition in which the body or certain body tissues suffer from lack of water. In serious enough cases, this can rapidly lead to death.

What causes dehydration?
Dehydration is a condition that occurs when a person loses more fluids than he or she takes in. Under normal conditions, we all lose body water daily through sweat, tears, urine & stool. In a healthy person, this water is replaced by drinking fluids & eating foods that contain water. When a person becomes so sick with fever, diarrhea, or vomiting or if an individual is overexposed to the sun, or has limited access to water, dehydration occurs. This is caused when the body loses water content & essential body salts such as sodium, potassium, calcium bicarbonate & phosphate.

Occasionally, dehydration can be caused by drugs, such as diuretics*, which deplete body fluids & electrolytes. Whatever the cause, dehydration should be treated as soon as possible.

For us hikers it can easily be caused by not drinking enough water often enough. When someone gets dehydrated, it means the amount of water in his or her body has dropped below its adequate level (our bodies are about 2/3 water). Small decreases don't cause problems, & in most cases, they go completely unnoticed. But losing larger amounts of water can sometimes make a person feel quite sick.

* Some sample diuretics: Soda / Pop (with caffeine), coffee, tea, alcohol (yes, even beer, sorry!), many medications especially those for heart patients (Lasix is commonly called a “water pill” it’s function is to eliminate water from the body and it does so VERY WELL.) Some who regularly drink caffeine report no additional loss of fluid, however I suggest: Why take a chance? Also, try to drink more water to "compensate".

What are the signs/symptoms of dehydration?
The following are the most common symptoms of dehydration, although each individual may experience symptoms differently. Symptoms may include:

Thirst (late sign/symptom) one of the most obvious, so pay close attention to it.
Less-frequent urination
Dark urine (early sign/symptom, be aware!)
Dry skin (late sign/symptom)
Fatigue
Light-headedness
Dizziness
Confusion
Dry mouth & mucous membranes
Increased heart rate & breathing (possibly with associated chest pains)Please note that thirst is a late sign/symptom; do NOT rely on thirst as an indicator of need for water. As Andrew “Iceman” Priestley states:

“It takes a while for that water to work through your system. You can be drinking & still be dehydrated. By the time you feel thirsty, you are over a quart low. If you never make up that quart, you'll still feel thirsty.
I drink almost constantly while hiking. I keep 2 liters on me if at all possible & drink A LOT. Frequent pee breaks become a valuable method of judging your level of hydration. Toss a packet of sport's drink concentrate in once a day as well; the extra electrolytes & such are good for you when your water throughput is high. During hot summer months I probably drink upward of 1.5 to 2 gallons of water a day when hiking. But then I sweat a lot.”

I can hear you say: “Two Gallons? That is way too much!” Yes, the (old) recommendation from the medical community was to "drink Six to Eight Quarts a day". A quart is ¼ of a gallon, so yes 8 quarts = 2 gallons. Almost no one drinks that much & most people are chronically dehydrated, and then they go hiking. The 6 to 8 Quart recommendation is for “strenuous activity” and may very well be way outdated. The point is still drink a lot of water. I do believe that hiking in the mountains carrying a backpack would qualify as strenuous activity, don’t you. Also, please note that in severe cases of dehydration, it takes anywhere from 48 to 72 hours to completely replenish water to normal levels.

Hints / tips:
Drink at least a quart of water first thing in the morning before even starting out; it won't keep you from getting thirsty, but by putting a quart in right away, it postpones the thirst by flooding the system before you even start hiking.

Also take a big drink every time you get to a decent water source & this is also a good time to check the water bottle levels at every source to make sure your not running too low; this is CRITICALLY important if you're using a hydration system/suck tube.

Get in the habit of checking your supply or sooner or later, you'll run out several miles from the next water. Many also keep a full quart by His/Her head at night so if they wake up several times during the night, they can take several short drinks; this keeps one from "drying out" during the night.

And lastly, don't forget to drink water when you're in town, many folks drink nothing but beer or soda in town. The easiest way to do this in town is to ask for ice water with your meals, & drink this instead of or in addition to an alternate beverage. But the key thing is to drink a lot of water & drink it often. Dehydration weakens muscles & tendons, & leaves you chronically fatigued. Most of the time when hikers complain of feeling poorly, feeling exhausted, all achy & irritable, these are all symptoms of chronic dehydration, & this is easily avoidable. Drink water BEFORE you get thirsty, & drink even when you're NOT thirsty, & however much you're drinking, drink more. Nothing like that good Mountain Spring Water, girls & guys.

So, now you are dehydrated, what to do?
To counter dehydration, you need to restore the proper balance of water in your body. On the trail this means drinking copious amounts of water, as a start. If you find a decent water source, set up camp then & there. No, you do not continue hiking, remember it can take: “anywhere from 48 to 72 hours to completely replenish water to normal levels.” So you need to STOP and get re-hydrated NOW! The trail will still be there, & the hike will be much more fun if you are properly hydrated. Added salt is still controversial, some say yes, some say no, & still others say in limited amounts. I lean toward no or very limited additional salt, especially if you are eating mostly pre-packaged things (Ramen flavor packets are mostly salt) you are getting ample salt, and besides the problem is too little water not too little salt. “But my sweat is salty, so I must be loosing salt”. Not necessarily, much of that “salt taste” is excess salt your body is getting rid of. Anyway: take a full day off, drink the above 2 gallons of water as a start then drink more. Probably, when you are peeing clear the majority of the crisis is over, you may then continue with your hike, but please take it slow and continue to drink and drink and drink.
An example: I got dehydrated at work, my partner started a 1-liter IV on me, and at the hospital I was diagnosed with moderate dehydration. After 2 liters of IV fluid and about 2 liters of oral water I was released from the hospital, I didn’t feel 100% for over 48 hrs. I had “endless thirsts” for about another 24 hours after that.

Survival Situation
Dehydration & heat exhaustion & stroke can be very dangerous. In the outdoors, it cannot be stressed enough: If you cannot get to a clean water supply, GO AHEAD & DRINK THE WATER. It is best to re-hydrate yourself, whether it is from creek, stream or lake. Your survival might depend on it. When you are then found & get back to a location where you can be treated, the health-care professionals can treat your symptoms at that point in time. For example, Guardia Labia, which is the very common organism that causes diarrhea, the incubation for Guardia is approximately 3 weeks. You will be found most likely in less time than that, & you are not going to suffer any symptoms until you get back. So, hydration is key. Please drink the water if you are in a situation that warrants that.

Great overview on the topic. I would add the following suggestions:

Whenever you think of taking a drink ...stop and take a drink. That might sound profound but a lot of hikers know they are thirsty but wait way too long to give in to the urge. During a sustained long distance hike you will always be "behind" in terms of hydration.

Compliment your water intake with salts. Drinking only water while hiking hard and perspiring heavily can dilute the available salts (electrolytes) in your blood stream and cause symptoms similar to heat exhaustion. Either eat foods with salt or alternate water intake with some form of sports drink that contains electrolytes.

'Slogger
AT 2003

Dehydration can sneak up on an experienced hiker just as well as it can for an inexperienced hiker.

I got dehydrated on the CDT in Montana, and thought I could just tough it out - WRONG!! Two liters of water for a 19 mile day up and down on the divide fell way short, so I was reduced to rationing. I started to realize how bad a mistake I had made about mile 17 when my eyes would no longer focus on the map. What happened next was a bit of incredible luck. I ran into two trail angels who immediately recognized a hurtin' unit. They gave me water and drove me into town, which possibly saved my life.

But my troubles weren't over (I was far gone). I went to relieve myself and realized I had blood in my urine. Then I made my next big mistake (my brain was no longer functioning at this point). I went and had a beer.

Wrong again. I quickly lapsed into unconciousness and was transported to the nearest hospital, where there was concern about possible kidney damage. They pumped me full of fluids and I gradually recovered.

There's a lesson here. The idea that you can tough out dehydration is pretty foolish.

Most of what we believe about dehydration and drinking plenty of water is myth and has no medical or scientific evidence to support it. Consider that first commandment of good health: Drink at least eight 8-ounce glasses of water a day. This unquestioned rule is itself a question mark. Most nutritionists have no idea where it comes from. "I can't even tell you that," says Barbara Rolls, a nutrition researcher at Pennsylvania State University, "and I've written a book on water."

Kidney specialists do agree on one thing, however: that the 8-by-8 rule is a gross overestimate of any required minimum. To replace daily losses of water, an average-sized adult with healthy kidneys sitting in a temperate climate needs no more than one liter of fluid, according to Jurgen Schnermann, a kidney physiologist at the National Institutes of Health.

One liter is the equivalent of about four 8-ounce glasses. According to most estimates, that's roughly the amount of water most Americans get in solid food. In short, though doctors don't recommend it, many of us could cover our bare-minimum daily water needs without drinking anything during the day.

The way it's almost always stated, in books, magazines and newspapers, the 8-by-8 rule specifically discounts caffeinated beverages, such as coffee. This is flat wrong. Caffeine does cause a loss of water, but only a fraction of what you're adding by drinking the beverage. In people who don't regularly consume caffeine, for example, researchers say that a cup of java actually adds about two-thirds the amount of hydrating fluid that's in a cup of water.

Regular coffee and tea drinkers become accustomed to caffeine and lose little, if any, fluid. In a study published in the Journal of the American College of Nutrition, researchers at the Center for Human Nutrition in Omaha measured how different combinations of water, coffee and caffeinated sodas affected the hydration status of healthy adults who drink caffeinated beverages routinely. "We found no significant differences at all," says nutritionist Ann Grandjean, the study's lead author. "The purpose of the study was to find out if caffeine is dehydrating in healthy people who are drinking normal amounts of it. It is not."

The same goes for tea, juice, milk and caffeinated sodas: One glass provides about the same amount of hydrating fluid as a glass of water. The only common drinks that produce a net loss of fluids are those containing alcohol--and usually it takes more than one of those to cause noticeable dehydration, doctors say.


Thirst is your best indicator. This mechanism almost always kicks in when we've lost between 1% and 2% of body water. There's no evidence that this 1 to 2% decrease is harmful in any way. Thus, there is really no need to 'prevent' this slight decrease in body water by drinking a specified amount in the absence of thirst.

None of the above is to say that dehydration is not something we shouldn't be aware of and watch for, it's just to point out that most, if not all, of what most people "know" regarding it simply isn't true.

I had to go back and dig to find the source of the information in my previous post. To give credit to the original author, most of the information was culled from an article in the LA Times by Benedict Carey.

I have been suspect of the 8-by-8 rule for some time. I heard the same thing that kncats is saying on TV just the other day (hey, if it's on TV it must be true, right?). I'm sure all the bottled water manufacturers don't want this to get out though! This being said, backpacking is hard work and naturally a hiker is going to require more fluid intake than a person who isn't active.
Last year while on an AT section hike, I felt like I was starting to get dehydrated. I got a metallic taste in my mouth and felt fatiqued. I'm not sure if it was just dehydration or was caused by the loss of potassium and other salts. My poly shirt was caked with salt.

Hey, kncats, I see you are in Newport News. I was born and raised in Portsmouth! Ah, the Old Dominion, how do miss my native state.

2002 was a very hot, dry dry summer. The day I climbed Mt Cube I was so dehydrated that I was nauseated. I stumbled down the mountain and hitched a ride up to the Mt Cube Sugar House (I think that is what it was called...). My thoart was so dry I could barely speak. The owner of the maple syrup place took me in. She gave me oodles of water, bananas and tomatoes. Luckily my husband was coming that very night for a visit and he found me there (the lady was nice enough to call the airport and leave a message and directions for my husband.) He force me full of fluids for the next 3 days.

It was only a week or so later that I ended up in the hospital with West Nile Fever and Lyme. I was given fluids by IV. The nurses were monitoring my fluid out put and were horrified that I did not pee for almost 32 hours.

Edginess, nausea, fatigue, joint pain, disorientation are just a few of the signs of dehydration. DRINK DRINK DRINK...

Thanks Doctari for all the wonderful info you posted and for bringing the topic up. It is really much more serious then most people think.

Sue/HH

In 2004 I ran a marathon 85 degree heat. From Start to finish I lost 11 pounds -- and even THAT was after drinking water at every single stop I could. The medical tent was so full after the race that I couldn't even get in. Afterwards I was so tired I could hardly walk. I frequently had to put my head down and just rest for 20 minutes at a time. I went to a party with my friends (who had also run the marathon) that evening and drank as much water/gatorade as I could, but the next day I was still 6 pounds under normal weight.

So these days, I have NO problem carrying around a few extra pounds of water while hiking.

Doctari,

That's a bunch of good stuff you just wrote. And very informative. Yes sir.

I remember one time, it was in and around Jan '01 as I was hiking from Hot Springs to Erwin. I was at a shelter, I can't remember the name, that was located on top of a ridge. The water source was about a half mile down a steep decline, maybe less. I had went there and got filled up when I got to the shelter.

Later that night as I turned in I forgot to put my water bottle in my sleeping bag with me. The next morn it was frozen solid. I checked the book and it said a water source was about 2.5 miles north. I figured I'd be okay. I packed and began walking.

Well it was one of those winter days in the south that occasionally gets warm as the sun gets higher in the sky. it turned out to be 50 that day.

By the time I get to the water source, it was dry. I had packed the bottle inside my jacket between my body. I pulled it out and drank what little water that had melted.

I hung the bottle on the pack hoping that the sun would help. Not.

As I walked on I became thirstier. After about 1.5 miles I am dehydrated! And I am thinking WATER!

It was so unreal, my senses came full alert! My ears started really listening for a brook, my eys were looking intently into the washes for any sign, my nose was sniffing for any sign of water.

Another mile or so I smelled WATER! I went full alert! Iwas looking everywhere!

There was a wash and I went down there for about a half mile. All at once I noticed the smell of water became less. I went back up the trail and it got stronger. I had me one of those good ole foxhole prayers, I was even whimpering for effect! It worked!

I came upon the trail where I had left my pack right in the middle, probably not a wise thing to do. There were some Rhodadendron bushes on the other side of the trail and I could smell water coming from them. So I burst thru the brush and there was a clearing and right in the middle was a mud bog with all kinds of deer and hog prints embedded in the mud. And leaves, wet, soggy wet. I grabbed a handfull and shoved them into my mouth!

I got down on my knees and scratched away some leaves and dug a hole. Water slowly seeped into the hole. I dug deeper so more water could go in. When it filled, I shoved my empty water bottle into it and filled it! The smell was putred, rotting leaves and all. I started to drink but thought I had better treat it first with iodine.

Back to my pack I go and put the iodine into it. I wait a half hour like the bottle says to do, suffering the whole time. Then I drank that whole thing down. I had energy out of this world! What ectasy!

I went and filled my bottle once more and continued my hike north. About two miles as I neared the shelter I come across a gushing stream. I dived in! Pack and all, burying my face, taking in gulp after gulp! I drank like a maniac!

Never, never do I hope I have to experience that again.

One other time I experienced dehydration in southern Penn. But thats another story..............

wanderer

Getting drunk is so much easier when dehydrated. Not that I condone that sort of thing... of course.

Re: Kncats
I thought my info was current. I did check many sources, but then again they may simply have been quoting old sources & passing it off (unknowingly as I am?) as current. Nevertheless, I think most will agree that drinking alot of water is good, even if not as much as 2 gallons :) I will look up the article you qoute, thanks!
I still believe that the "keep your urine clear" is a sound "Rule" & I know I feel better when I apply that rule.

Thanks for the post!

To all others:
The post is decidedly open for comments K. It is just a preliminary post, but I posted it now to get a jump on the "danger season" & hope to refine (do more reasearch) in the weeks to come. ANY: ideas, comments, examples, etc very welcome.

Again, thanks to Kncats, & all who have & shall post.

Doctari.

What a spring we have had this year, no threat of dehydration here. A front has become imbedded off the Maine coast and we have had rain 19 of the last 21 days. Stream fords are difficult and some parts of the trail were still not assessable a week ago. The Kennebec is so wide that the ferryman, Steve, has to carry a GPS to find the other shore. Rivers have flooded twice and there are flood warnings out for today. The longest river in Maine is now The Applachian Trail. I remember on my thru hike dehydration was a problem in Virginia and Pa. Good water was difficult to find in New Jersey and everyone paid very close attention to the trail registers as they were the most accurate way to find where water was available. Not a problem this year when you get to Maine, no dehydration here this year, at least not early in the season. Bring your fishing pole as the fish and wildlife department is ready to stock trout of the actual trail as the streams are too full of water and they are afraid the trout might actually drown. I'd give more detail but my wife has gone for a swim in our basement and is shouting for a towel.
:welcome To Maine, the surf is up on the AT

Doctari, thanks for the information and for starting this thread. I recently finished a 2-week section hike in Damascus. For the first time in my 30+ years of hiking and backpacking, I was dehydrated after a 20 mile day; my pee turned from dark yellow to red. I thought I had drunk sufficiently but apparently not. Along with obvious concern, I was also puzzled because although this was a big mileage day by my standards, it was also easy hiking. I've experienced much more stressful hiking days in much hotter weather where I "felt" more dehydrated. So my questions are:

1. As our bodies age, we all know they change. Can the aging provess affect the body's response to dehydration?

2. I'm (reluctantly) taking Lipitor for my high chloresterol. Does this make a difference? What about my taking baby aspirin and supplements - flax oil, fish oil, saw palmetto?

One lesson is that I need to drink regardless of how thirsty I feel. So maybe the danger isn't on the obviously difficult days and places i.e. hot, dry climates - but even more so in "nice" weather when we tend to underestimate the potential for dehydration.

Re: Kncats
I thought my info was current. I did check many sources, but then again they may simply have been quoting old sources & passing it off (unknowingly as I am?) as current. Nevertheless, I think most will agree that drinking alot of water is good, even if not as much as 2 gallons :) I will look up the article you qoute, thanks!
I still believe that the "keep your urine clear" is a sound "Rule" & I know I feel better when I apply that rule.

Thanks for the post!
The most recent study I've seen reported was from last year (2004).

lol, Speaking of quoting and requoting old sources, the best information I've been able to find on the origins of the 8 x 8 glasses a day theory is that it started from an FDA report (or whatever the agency was back then) from the late 50's or early 60's that stated the TOTAL amount of fluid needed daily on average was 64 ounces. However, that recommendation included liquids contained in the food we eat. Subsequently the part about the food was omitted and it became 64 ounces of water.

I totally agree with you on the need to be aware of and prevent dehydration. But it seems to me that many people develop an unnecessary fear of it and carry too much weight as a result. Except for athletes and soldiers, thirst really is a good indication of when to drink. Just drink often enough and in sufficient quantity to keep it at bay.

Only soda/pop containing caffeine would increase urine output, not all soda/pop.

I drink a lot of water and I can definitely feel the performance boost from staying hydrated. There is such a thing as too much of a good thing and recent reports have discussed the threat of overhydrating and messing up brain function in the process. People have died from over-hydrating interfering with autonomic nervous system function. Mostly this is seen in soldiers and marathoners who drink too much. Many marathoners were actually gaining water weight during their runs because they drank so much water. OUCH!

That said...the water your body needs to get through the average sedentary day of the average American, is a far cry from what it needs to get through a day of hiking on the AT with 25-65 pounds of gear on your back and temps that frequently get into the upper 90's and even low 100's in the Summer. Your body will burn through fluids like a chain saw burns through bar oil. So fluid intake guidelines for sedentary lifestyles are moot when you are out hiking. You need to take in enough fluid to sustain YOUR body under Those conditions and at that activity level. Some people won't need more than a couple quarts a day on a wooded trail like the AT, others of us will refil our bottles 4 times that day just to stay ahead of our fluid loss.

Thirst is a good indicator for a sedentary person. Absolutely, because fluid loss will be slower than your ability to access and replenish your fluid levels. In an active person, hiking and sweating so fast that you can watch the sweat bead up. The thirst threshold will, first off, pass without being noticed because your mind is busy elsewhere. Second, you may not have easy access to water, especially if you let your bottle go dry and you are depending upon chemical treatment methods with extended wait times. It could easily be another 30 minutes before you can safely drink...if you can get to water right away.

So while new advice says that you don't necessarily have to drink as much as all that. Listen to your body and stay ahead of its cries for help.

Also, the thing about overhydration that wrecks you is loss of necessary salts and electrolytes in brain and spinal fluid. Your body mis-interprets the fact that it's signals aren't getting through cleanly thanks to the low conductivity of the watery fluid and sends more fluid (thinking that there isn't enough) the result is waterlogged brain and too much pressure in the skull. If you need to drink A LOT of fluids like I do, it behooves you to drink at least some of that as sports drinks and to carry salty snackfoods to keep your saline and electrolytes up just in case you do overdo it. I use Gatorade powder and I chew salted-in-shell sunflower seeds.

I'm not calling the new information wrong, just saying that it is only right under a specific set of assumptions...assumptions that do not hold if your lifestyle is active or is spent out in hot or dry conditions. So be prepared to drink a lot more water on the trail.

First off thanks for a great article .:clap Admittedly I a big coffee drinker and suffer moderate dehydration all the time. Naturally hiking makes it worse so I try to go with a 4 quart a day minimum unless it's summer, then 6 is my goal. Back in the 70's I went through a 5 day desert survival course in the military and the flight surgeon and corpsmen who lectured us pointed out that if you didn't feel the urge to urinate almost constantly, then you weren't well hydrated and the 3 Cs-Check Color Constantly (urine that is). Back then we were also urged to take at least 2 salt tabs a day. Of course translating that advise into the real-world was very difficult with water in any quantity almost impossible to come by. At the end of the training my green nomex flight suit was almost white and stiff as a board from salt in my sweat drying on it, and I was peeing what would pass for bourbon color-wise. It took close to a month to really feel ok after that experience and I was in my early 20's and in great shape. All that said, I have to question the wisdom of those who plan to limit water capacity to a 20 oz pepsi bottle because the weight is an issue. I certainly haven't hiked much of the AT but there's lots of places I roam where water can get pretty scarce in mid summer so I carry as much as I can, I guess I'm just scared of running out.

I think the difference lies in theory versus practice. My experience is much like that of NICKTHEGREEK. I am not caught up in any MYTH and it doesn't require extensive medical science to validate what happens when I become dehydrated. The body does a pretty good job of maintaining a balance, within limits, but without sufficient water onboard the machine starts to get sluggish.

As a kidney stone maker, I am pretty tuned in to the effects of dehydration. I hiked the entire AT in 2003 with significant kidney stone disease and the only thing that kept me going (other than my innate stubborness) was staying well hydrated and eating foods that contained salts.

'Slogger

Only soda/pop containing caffeine would increase urine output, not all soda/pop.


True, I missed that on the (rapid) edit.

Thanks!

Doctari.

I usually carry one three liter bladder in my hydration pack, and a couple of bottles stuffed here and there. The weight is a factor, yes, but I need a lot of water while hiking.