Manag­ing De­hy­dra­tion

RECOIL OFFGRID - - Contents - By Dr. Dave Miller

As self-re­liant peo­ple, we un­der­stand the im­por­tance of wa­ter. We store it in our homes and bug-out shel­ters, carry it in our ve­hi­cles, and bring it with us dur­ing ev­ery hike or work­out. The prob­lem is that even with an abun­dance of avail­able wa­ter, we of­ten ne­glect the wa­ter within our own bod­ies.

Nearly two thirds of your body weight is wa­ter, yet tak­ing that fluid sta­tus for granted, par­tic­u­larly dur­ing stren­u­ous ac­tiv­ity, fre­quently leads to de­hy­dra­tion and death. Here we’ll dis­cuss the fac­tors that con­trib­ute to wa­ter loss, fol­lowed by signs and symp­toms of de­hy­dra­tion. Lastly, we’ll dis­cuss some strate­gies for fluid man­age­ment.

Ac­tiv­ity and En­vi­ron­ment

There are sev­eral fac­tors that con­trib­ute to fluid loss. Ex­er­cise and tem­per­a­ture are among the big­gest causes. Clearly, the hot­ter the en­vi­ron­ment or the more in­tense and pro­longed the ac­tiv­ity, the more wa­ter we lose, es­pe­cially if we nat­u­rally sweat a lot. Don’t just as­sume, how­ever, that in­creased ac­tiv­ity and tem­per­a­ture are the only things to watch out for. It’s easy to think about re­plac­ing wa­ter when it’s hot out­side, but many as­sume re­plac­ing it dur­ing the cold, dry win­ter months, isn’t as crit­i­cal. De­hy­dra­tion can and does still oc­cur when you’re ex­posed to lower tem­per­a­tures.

De­con­di­tion­ing also plays a part in in­creased fluid loss. The sim­ple truth is that be­ing out of shape will re­quire you to ex­ert more en­ergy and sweat more than usual, which may cause some to suc­cumb to the heat more eas­ily. Many peo­ple don’t re­al­ize that alti­tude also con­trib­utes to fluid loss. The higher you go, the more you per­spire and lose wa­ter through in­creased res­pi­ra­tion. The wa­ter/sweat also evap­o­rates faster at higher al­ti­tudes due to higher at­mo­spheric pres­sures, es­pe­cially above 5,000 feet. Be­ing aware of the fac­tors that con­trib­ute to wa­ter loss is im­por­tant.

Ob­vi­ous signs of de­hy­dra­tion are thirst, dark-col­ored urine, and fa­tigue, which oc­cur in mild de­hy­dra­tion (less than 5-per­cent body fluid loss). As wa­ter loss be­comes mod­er­ate (5- to 10-per­cent loss), we can ex­pe­ri­ence wors­en­ing of the afore­men­tioned symp­toms as well as in­creased heart rate, weak pulse, de­creased urine out­put, de­creased sweat­ing, and de­creased lev­els of alert­ness.


When de­hy­dra­tion is se­vere (greater than 10-per­cent loss), the men­tal state can be drowsy, even ob­tunded, and per­spi­ra­tion can stop, with the skin hav­ing “goose pim­ples.” There’s very lit­tle urine out­put and the res­pi­ra­tory rate in­creases. This is a sit­u­a­tion that re­quires im­me­di­ate med­i­cal at­ten­tion, as it puts vi­tal or­gans at risk of per­ma­nent dam­age.

In or­der to es­ti­mate how much fluid to re­place, there’s a sim­ple cal­cu­la­tion. There are more pre­cise equa­tions that can be found on the In­ter­net, but here we’ll keep it sim­ple:

1) Take your weight in pounds, and di­vide by 2.2 to get your weight in kilo­grams.

2) Since your body is es­sen­tially 60-per­cent wa­ter, take your weight in kilo­grams mul­ti­plied by 0.6 to get the liters of wa­ter con­tained in your body. For ex­am­ple, if a male is 220 pounds, then the equa­tion is (220/2.2) x 0.6 = 60 liters of wa­ter in his body.

3) There­fore, in a case of mild de­hy­dra­tion (5 per­cent) for this 220-pound (100kg) male, who we just cal­cu­lated to have 60 liters of wa­ter in his body, would re­sult in 3L of wa­ter lost dur­ing the ac­tiv­ity (60L x 0.05 = 3L).

So with the signs of de­hy­dra­tion and the sim­ple cal­cu­la­tions above, we’ve one way to es­ti­mate how much wa­ter is lost dur­ing ac­tiv­ity. An­other is to weigh your­self be­fore any

ac­tiv­ity, then weigh your­self af­ter­ward to find out how much weight you lost. You can as­sume that the weight lost was all wa­ter weight and re­plen­ish ac­cord­ingly. As a gen­eral rule, 1 liter of wa­ter is equal to about 1 kilo­gram of weight. So, in our ex­am­ple, the man who lost 3 liters of fluid would have lost 3 kilo­grams of weight, or ap­prox­i­mately 6.5 pounds.

If you don’t have a scale and an­tic­i­pate a hard work­out in a hot en­vi­ron­ment, we’d rec­om­mend drink­ing a ½ liter of wa­ter a few hours be­fore the event, then about 250mL of wa­ter five to 10 min­utes prior to the ac­tiv­ity. Dur­ing ex­er­cise, I would rec­om­mend drink­ing about 250mL ev­ery 15 min­utes. This lat­ter rec­om­men­da­tion is ap­prox­i­mately the max­i­mum amount of fluid an av­er­age per­son can ab­sorb from the stom­ach in that time pe­riod.

Hav­ing a Wa­ter Sur­vival Plan

In a sur­vival sit­u­a­tion, how­ever, re­mem­ber from the rules of three that you can only sur­vive roughly three days with­out wa­ter. Main­tain­ing your hy­dra­tion in a sur­vival sit­u­a­tion is cru­cial. As the level of de­hy­dra­tion be­comes more se­vere, fa­tigue can in­ter­fere with per­form­ing tasks crit­i­cal to your own sur­vival. Men­tal clar­ity di­min­ishes rapidly but is re­cov­ered slowly. The best ap­proach is to pre­vent de­hy­dra­tion in the first place, by drink­ing wa­ter while you can. Try­ing to drink 250mL of wa­ter ev­ery 15 min­utes in a stress­ful bug-out sce­nario may be a rea­son­able goal, as­sum­ing your cache of wa­ter is plen­ti­ful. If you’re bug­ging in, you may be able to stretch that out to ev­ery one to two hours, de­pend­ing on am­bi­ent tem­per­a­ture and ac­tiv­ity level.

Oral Re­hy­dra­tion Salts

What about the ben­e­fit of oral re­hy­dra­tion salts? The World Health Or­ga­ni­za­tion has de­vel­oped an oral re­hy­dra­tion salt (ORS) that con­sists of sodium chlo­ride (2.6g), glu­cose (13.5g), potas­sium chlo­ride (1.5g), and sodium cit­rate (2.9g). These are avail­able through the in­ter­net; one packet is dis­solved in 1 liter of wa­ter. There are other ORS out there that you can put in a bot­tle of wa­ter, but they can have vary­ing amounts of these four com­po­nents.

The com­bi­na­tion of “salts” was de­vel­oped from treat­ing se­vere de­hy­dra­tion due to in­fec­tious di­ar­rhea in de­vel­op­ing coun­tries, where kids and adults were los­ing a lot of wa­ter and potas­sium. The potas­sium re­place­ment was im­por­tant to pre­vent car­diac com­pli­ca­tions. The glu­cose was added not so much for nu­tri­tion, but to as­sist in get­ting sodium into the cells. The sodium cit­rate was im­por­tant to neu­tral­ize the acid built up in a se­verely de­hy­drated body. Some com­mer­cial ORS may have mag­ne­sium (to help with potas­sium trans­port) and may not have the sodium cit­rate. The cit­rate would only be im­por­tant in very se­vere cases of de­hy­dra­tion. In a sur­vival sit­u­a­tion where there’s no ORS avail­able, you could make a so­lu­tion by us­ing 1 liter of wa­ter, 6 lev­eled tea­spoons of sugar (25.2g), and a half tea­spoon of ta­ble salt ( 2.9g).

Al­ter­nate Hy­dra­tion Meth­ods

What about sports drinks? While these were de­vel­oped to help aid ath­letes to re­cover faster, many physi­cians be­lieve that sports drinks are gen­er­ally not as help­ful as peo­ple be­lieve. The ben­e­fit you may per­ceive is the re­plen­ish­ment of glu­cose from the ac­tiv­ity. What’s of­ten lack­ing in these sugar-heavy bev­er­ages is the bal­ance of elec­trolytes to ac­com­pany the glu­cose. If you don’t have wa­ter, it may be a rea­son­able al­ter­na­tive to con­sume a sports drink; how­ever, it’s not rec­om­mended to rely on sports drinks when wa­ter is avail­able.

Should you avoid caf­feine? Con­trary to pop­u­lar be­lief, re­search shows that caf­feine usu­ally doesn’t act as a di­uretic. A di­uretic is a sub­stance that makes you uri­nate more than the fluid con­sumed and is com­monly used for those peo­ple with heart fail­ure. Mul­ti­ple fac­tors can sway the ar­gu­ment to­ward caf­feine be­ing a mild di­uretic. Are you de­hy­drated while drink­ing caf­feine? Are you used to drink­ing caf­feine? How much caf­feine is be­ing con­sumed at a time? If the an­swer to those ques­tions is yes, yes, and more than 360 mg of caf­feine, then you may no­tice a small di­uretic ef­fect. If you’re for­ag­ing for food in a sur­vival sit­u­a­tion, keep in mind that plants such as dan­de­lion, onion, gar­lic, grapes, wa­ter­melon, and as­para­gus can have a di­uretic ef­fect.

You may have heard that zinc can be help­ful in pre­vent­ing de­hy­dra­tion since it has been stud­ied in Africa dur­ing in­fec­tious di­ar­rhea out­breaks (e.g. cholera). Zinc boosts the im­mune sys­tem and aids in in­testi­nal trans­port of glu­cose and sodium. Stud­ies have sug­gested that in cases of se­vere in­fec­tious di­ar­rhea, pa­tients who were given zinc had a sig­nif­i­cant de­crease in sever­ity and du­ra­tion of di­ar­rhea. They were also less likely to have re­cur­rence of symp­toms for months af­ter­ward.

The amount of zinc used in these stud­ies was up to

20g a day for those over 6 months old, and 10g a day for those un­der 6 months old. Keep in mind that these were im­pov­er­ished coun­tries where zinc in­ges­tion through foods was poor. In our western cul­ture, we cer­tainly get our fair share of zinc in our foods. In a sur­vival sit­u­a­tion, we have foods like gar­lic, rasp­ber­ries, pump­kin seeds, cashews, al­monds, and as­para­gus that all con­tain good amounts of zinc. It’s not known whether con­sum­ing zinc in a milder form of de­hy­dra­tion is ben­e­fi­cial.

Health Con­sid­er­a­tions

There are a few phys­i­o­log­i­cal items to dis­cuss re­gard­ing de­hy­dra­tion as well. First, your gas­troin­testi­nal sys­tem al­ways seems to be the first or­gan sac­ri­ficed when blood vol­ume is low (e.g. de­hy­dra­tion). When you’re low on fluid, your body makes sure that your heart, brain, and lungs have all the fluid they need to keep you alive. If you eat while you’re de­hy­drated, your body doesn’t do a great job di­gest­ing the food, be­cause the stom­ach was shut down to shift blood (fluid) to other more im­por­tant or­gans. This is one of the rea­sons that you don’t feel hun­gry when you’re de­hy­drated.

An­other fac­tor in nu­tri­tion and fluid loss dur­ing a longterm sur­vival sce­nario is a pro­tein in our body called al­bu­min. Al­though al­bu­min has sev­eral im­por­tant roles in the body, for our pur­poses here, its job is to keep fluid in­side the blood ves­sels. If we re-visit the rules of three, we know we can sur­vive about three weeks with­out food. Al­though we have al­bu­min stored in our body, these lev­els can be de­pleted over a few weeks, es­pe­cially if food is scarce. When al­bu­min lev­els are low, wa­ter leaks out of the blood ves­sels and into the places where the tis­sues can­not use the wa­ter (this is called “third spac­ing”). This process de­creases blood vol­ume, de­creases blood pres­sure, and cre­ates an en­vi­ron­ment that leads to or­gan fail­ure and death.

Op­ti­mal fluid man­age­ment dur­ing ac­tiv­i­ties or dur­ing sur­vival sit­u­a­tions is es­sen­tial to main­tain peak per­for­mance. By rec­og­niz­ing the signs and symp­toms of de­hy­dra­tion, we might pre­vent a pro­gres­sion of de­hy­dra­tion that af­fects our per­for­mance. By manag­ing our fluid in­take to meet the de­mands of ac­tiv­ity and the losses of fluid, we can pre­pare to per­form at peak lev­els.


Oral re­hy­dra­tion salts of­ten come in such smallpack­ets like this ex­am­ple from Chi­nook Med­i­cal Gear. Keep some in your med­i­calgear stash in the event de­hy­dra­tion and wa­ter scarcity be­comes anis­sue.




Zinc sup­ple­ments are of­ten used to boost wa­ter re­ten­tion and ab­sorp­tion.

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