Editing Dehydration (section)

== Prevention ==
For routine activities, thirst is normally an adequate guide to maintain proper hydration.<ref>{{Cite book | url= http://www.nationalacademies.org/hmd/Reports/2004/Dietary-Reference-Intakes-Water-Potassium-Sodium-Chloride-and-Sulfate.aspx |title=Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate : Health and Medicine Division |isbn=9780309091695|language=en|access-date=2018-02-07 | author1 = Institute of Medicine | author2 = Food Nutrition Board |date=June 18, 2005|publisher=National Academies Press }}</ref> Minimum water intake will vary individually depending on weight, energy expenditure, age, sex, physical activity, environment, diet, and genetics.<ref>{{Cite journal |last1=Armstrong |first1=Lawrence E. |last2=Johnson |first2=Evan C. |date=2018-12-05 |title=Water Intake, Water Balance, and the Elusive Daily Water Requirement |journal=Nutrients |language=en |volume=10 |issue=12 |pages=1928 |doi=10.3390/nu10121928 |doi-access=free |issn=2072-6643 |pmc=6315424 |pmid=30563134}}</ref><ref>{{cite journal | vauthors = Yamada Y, Zhang X, Henderson ME, Sagayama H, Pontzer H, Watanabe D, Yoshida T, Kimura M, Ainslie PN, Andersen LF, Anderson LJ, Arab L, Baddou I, Bedu-Addo K, Blaak EE, Blanc S, Bonomi AG, Bouten CV, Bovet P, Buchowski MS, Butte NF, Camps SG, Close GL, Cooper JA, Cooper R, Das SK, Dugas LR, Eaton S, Ekelund U, Entringer S, Forrester T, Fudge BW, Goris AH, Gurven M, Halsey LG, Hambly C, El Hamdouchi A, Hoos MB, Hu S, Joonas N, Joosen AM, Katzmarzyk P, Kempen KP, Kraus WE, Kriengsinyos W, Kushner RF, Lambert EV, Leonard WR, Lessan N, Martin CK, Medin AC, Meijer EP, Morehen JC, Morton JP, Neuhouser ML, Nicklas TA, Ojiambo RM, Pietiläinen KH, Pitsiladis YP, Plange-Rhule J, Plasqui G, Prentice RL, Rabinovich RA, Racette SB, Raichlen DA, Ravussin E, Redman LM, Reilly JJ, Reynolds RM, Roberts SB, Schuit AJ, Sardinha LB, Silva AM, Sjödin AM, Stice E, Urlacher SS, Valenti G, Van Etten LM, Van Mil EA, Wells JC, Wilson G, Wood BM, Yanovski JA, Murphy-Alford AJ, Loechl CU, Luke AH, Rood J, Westerterp KR, Wong WW, Miyachi M, Schoeller DA, Speakman JR | title = Variation in human water turnover associated with environmental and lifestyle factors | journal = Science | volume = 378 | issue = 6622 | pages = 909–915 | date = November 2022 | pmid = 36423296 | pmc = 9764345 | doi = 10.1126/science.abm8668 | bibcode = 2022Sci...378..909I }}</ref> With exercise, exposure to hot environments, or a [[Adipsia|decreased thirst response]], additional water may be required. In [[athlete]]s in competition, drinking to [[thirst]] optimizes performance and safety, despite weight loss, and as of 2010, there was no scientific study showing that it is beneficial to stay ahead of thirst and maintain weight during exercise.<ref>{{cite journal | vauthors = Noakes TD | title = Is drinking to thirst optimum? | journal = Annals of Nutrition & Metabolism | volume = 57 | issue = Suppl 2 | pages = 9–17 | date = 2010 | pmid = 21346332 | doi = 10.1159/000322697 | doi-access = free }}</ref>

In warm or humid weather, or during heavy exertion, water loss can increase markedly, because humans have a large and widely variable capacity for sweating. Whole-body sweat losses in men can exceed 2 L/h during [[competitive sport]], with rates of 3–4 L/h observed during short-duration, high-intensity exercise in the heat.<ref name="ReferenceA">{{cite journal | vauthors = Taylor NA, Machado-Moreira CA | title = Regional variations in transepidermal water loss, eccrine sweat gland density, sweat secretion rates and electrolyte composition in resting and exercising humans | journal = Extreme Physiology & Medicine | volume = 2 | issue = 1 | pages = 4 | date = February 2013 | pmid = 23849497 | pmc = 3710196 | doi = 10.1186/2046-7648-2-4 | doi-access = free }}</ref> When such large amounts of water are being lost through perspiration, [[electrolytes]], especially sodium, are also being lost.<ref>{{Cite journal |last=Baker |first=Lindsay B. |date=March 2017 |title=Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability |journal=Sports Medicine |language=en |volume=47 |issue=S1 |pages=111–128 |doi=10.1007/s40279-017-0691-5 |issn=0112-1642 |pmc=5371639 |pmid=28332116}}</ref>

In most athletes exercising and sweating for 4–5 hours with a sweat sodium concentration of less than 50&nbsp;mmol/L, the total sodium lost is less than 10% of total body stores (total stores are approximately 2,500&nbsp;mmol, or 58 g for a 70-kg person).<ref name="Edward F Coyle 2004">{{cite journal | vauthors = Coyle EF | title = Fluid and fuel intake during exercise | journal = Journal of Sports Sciences | volume = 22 | issue = 1 | pages = 39–55 | date = January 2004 | pmid = 14971432 | doi = 10.1080/0264041031000140545 | s2cid = 14693195 | citeseerx = 10.1.1.321.6991 }}</ref> These losses appear to be well tolerated by most people. The inclusion of sodium in fluid replacement drinks has some theoretical benefits<ref name="Edward F Coyle 2004"/> and poses little or no risk, so long as these fluids are hypotonic (since the mainstay of dehydration prevention is the replacement of free water losses).