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Measured against water

Does beer dehydrate you? Beer, wine and non-alcoholic beer, measured

Lager was no different from water at rest — after exercise, full-strength beer often lost more

Less than its reputation suggests, and it depends on the strength. At rest, a litre of lager was not measurably different from a litre of water: 0.99 on the beverage hydration index, against water's 1.00. Alcohol does make you pee more — the usual explanation is that it suppresses vasopressin, the antidiuretic hormone that makes the kidneys hold on to water — but the extra is short-lived: in older men, wine and spirits briefly raised urine output, 5% beer did not, and nothing differed after 24 hours. After exercise, full-strength beer is a poor way to rehydrate. Water Goose has no alcohol preset, and nothing on this page is a reason to drink.1,2,3,4

What a can holds
Lager at rest
0.991
2-h index vs water 1.00 (SD 0.31, read from the figure). Not a significant difference.
4.6% beer after exercise
1,218 mL4
Urine over 3 hours, against 774 mL after the same volume of water
Beer, wine, spirits at 24 h
No difference3
30 g of alcohol in older men: wine and spirits briefly raised 4-hour urine; 5% beer did not
Alcohol in a 12 fl oz can
14 g5
Regular beer by USDA's figures; light beer about 11 g, and USDA's non-alcoholic beer and malt beverage entry about 1 g

Last reviewed 20 sourcesWritten from the studies, not from other websites

The measurement

Is beer as hydrating as water?

The beverage hydration index compares the urine you produce after a litre of a drink with the urine you produce after a litre of still water, two hours after you finish: above 1.00 means more of it stayed in you. In the 2016 trial that created it, 72 rested, already-hydrated men each drank still water and three of the twelve other drinks, a litre at a time over 30 minutes; about 17 of them drank the lager. Lager came out at 0.99, statistically indistinguishable from water — as were cola, coffee, tea and a sports drink. It is the only measurement of beer on this protocol, and the paper never said how strong the lager was.

This pageAbove waterNo differenceWater = 1.00
  • Skimmed milk1.58
  • Oral rehydration solution1.54
  • Full-fat milk1.50
  • Orange juice1.39
  • Cola1.23
  • Diet cola1.08
  • Cold black tea1.07
  • Hot black tea1.03
  • Sports drink1.02
  • Still waterreference1.00
  • Lager0.99
  • Sparkling water0.98
  • Coffee (hot, black)0.91

Significance as marked on the paper’s Figure 2: ** P<0.01, * P<0.05 vs waterWhiskers are 1 SD

BHI = urine after still water ÷ urine after the test drink, 2 h after drinking ended. 72 healthy, recreationally active men aged 18-35, rested, fasted overnight and euhydrated. 1 L of each drink over 30 min in four equal portions; urine collected hourly for 4 h after drinking ended. Each man drank still water plus 3 of the 12 other drinks on separate mornings. Cold drinks 4-6 C, hot tea and coffee 60 C.1Funding: Funded by a grant from the European Hydration Institute (EHI). Prof Maughan chairs the EHI Scientific Advisory Board (not the Institute itself); Dr Watson has also received EHI funding.
Show the data table
Two-hour beverage hydration index for every drink tested, with standard deviations and how each was reported
DrinkIndex2 hCorrectedwater contentSDvs watern
Skimmed milkTesco, 0.1% fat1.581.440.60Above water17
Oral rehydration solutionDioralyte, made up with Highland Spring water1.541.500.74Above water17
Full-fat milkTesco, 3.6% fat1.501.320.58Above water17
Orange juiceTesco Everyday Value1.391.240.64≈Above water16
ColaCoca-Cola1.231.090.54≈No detected difference17
Diet colaDiet Coke1.081.080.24≈No detected difference16
Cold black teaPG tips1.071.070.59≈No detected difference17
Hot black teaPG tips1.031.030.24≈No detected difference15
Sports drinkPowerade1.020.980.24≈No detected difference17
Still waterHighland Spring1.001.00—Reference drink72
LagerCarling0.990.940.31≈No detected difference17
Sparkling waterHighland Spring0.980.980.20≈No detected difference17
Coffee (hot, black)Nescafe Original instant0.910.900.31≈No detected difference17

≈ marks a standard deviation read from the paper’s figures rather than its text. “Corrected” adjusts each drink for its own water content, which is the fairer comparison and the one that moves orange juice below significance.

What this number is not

  • — About 17 drinkers per test drink against a pooled water arm, so small differences such as coffee vs water cannot be detected.
  • — Rested, already-hydrated young men drinking 1 L in 30 min; the result describes a 2-4 h window, not all-day hydration.
  • — Caffeine at 96-212 mg in these drinks had no effect on net fluid balance. The authors cite a threshold of about 250-300 mg for a measurable diuretic effect (Maughan & Griffin 2003).
  • — The lager's alcohol content was not reported, and no numeric 4-h BHI was reported for any drink.
  • — Nine of the twelve BHI standard deviations, and eight of the twelve means, are only in the figures; they were read from the figure's vector data and match the text values to about 0.01.
  • — The abstract says the BHI was corrected for water content, but the 1.58, 1.54 and 1.50 values are the uncorrected BHI.

What 0.99 does not mean

It is not "beer hydrates as well as water" in general. About 17 men drank the lager, the index repeats with a coefficient of variation of 18%, its value was read from the paper's figure, and the paper never said how strong the lager was. It describes one litre drunk in 30 minutes by rested, already-hydrated young men; corrected for the lager being 94% water, it falls to 0.94. The authors add that the alcohol did not raise urine output above the other drinks, but may have cancelled out the extra retention the lager's energy content would otherwise have bought.1

Strength matters

When does beer dehydrate you?

The honest answer is a ladder, not a yes or no. How strong the drink is, how much of it there is and whether you were already dehydrated each change the result, and every trial behind it is small.

  • Alcohol-free, and up to 2%: no different from water

    After a mild sweat, non-alcoholic beer kept 36% of what was drunk over five hours and 2% beer 36%, against 34% for water — no significant difference. An older trial found no difference in any measure after exercise when the same alcohol-free beer had 1 or 2% alcohol added.6,7

  • Around 4-5% after exercise: often more urine, slower recovery

    Replace a sweat loss with 4.6% beer and more of it comes straight back out: 1,218 mL of urine over three hours against 774 mL for water. A 4.8% beer produced 2,175 mL over four hours against 1,477 mL for a 2.3% beer with added sodium, and the same alcohol-free beer at 4% slowed the recovery of blood and plasma volume. Not every trial agrees: across 0 to 4% beers, six-hour urine did not differ significantly, though it tended to rise with the alcohol; and after a 1% sweat loss replaced one-for-one, 5% beer's five-hour urine (580 mL against 478 mL) and retention (21% against 34%) were not significantly different from water's.4,8,7,6

  • Already well hydrated, the alcohol shows

    A litre of 4% beer produced 1,279 mL of urine over four hours in well-hydrated men, against 1,121 mL for the same beer without alcohol. When the same men started out dehydrated, the gap shrank to 261 mL against 174 mL and was no longer significant: a body short of water holds on to it, and NATA's position statement ranks that effect above the alcohol's.9,10

  • Wine and spirits: a small, short rise

    In older men given 30 g of alcohol with lunch, wine at 13.5% and spirits at 35% raised four-hour urine output against their alcohol-free counterparts; the same alcohol as 5% beer did not. By 24 hours none of the three differed, and the extra urine from wine or spirits was not significantly larger than from beer.3

  • Every trial here was in men

    Every trial on this page tested men only — young and active in most, 60 to 75 in one. The Dutch post-exercise trial notes that alcohol's effect on rehydration had not been studied in women, and the older-men trial warns against carrying its results over to them.6,3

  • The fluid comes with alcohol and calories

    A 12 fl oz can of regular beer carries about 14 g of alcohol and 155 kcal by USDA's figures; a light beer about 11 g and 104 kcal. Hydration is the least of what a can of beer carries, which is why this page measures it and recommends nothing.5

Pregnant, or told not to drink? None of this applies

The NHS advice is that if you are pregnant or planning to become pregnant, you should not drink alcohol. If a clinician has told you not to drink, or has capped how much fluid you take, follow that rather than anything measured in these small trials of healthy men.11

Composition

What is in a can of beer, light beer and non-alcoholic beer?

USDA's regular beer, light beer and non-alcoholic beer (a malt-beverage entry) on one scale, with water as the baseline. Switch the serving to whatever you actually pour.

Serving size

Showing 355 mL · 12 fl oz of each.

Composition of regular, light and non-alcoholic beer and still water per 355 mL serving, from USDA FoodData Central
DrinkWaterby weightWater in itper servingCaloriesSugarsProteinSodiumPotassiumCalcium
Beer, regular92%331mL11.2 fl oz155kcal0g1.7g14mg97mg14mg
Light beer94.9%342mL11.5 fl oz104kcal0.3g0.9g14mg76mg14mg
Non-alcoholic beer / malt beverage (USDA)91.2%328mL11.1 fl oz133kcal29g0.8g47mg29mg25mg
Still water, for comparison99.9%360mL12.2 fl oz0kcal0g0g14mg0mg11mg

USDA publishes composition per 100 grams, so each serving is converted through the item's density — 1.0144 g/mL for all three beers and for water, from USDA's rounded 12 fl oz and cup portion weights. That rounding puts the water row a shade above the volume poured; read it as "essentially all of it". Water mass is shown as millilitres on the basis that 1 g of water is 1 mL. The table has no alcohol column, so the alcohol per can is listed below it.5

Which USDA entries these are
  • Beer, regular: Beer — FDC 2710616, Food and Nutrient Database for Dietary Studies (FNDDS) 2024-10-31
  • Light beer: Beer, light — FDC 2710617, Food and Nutrient Database for Dietary Studies (FNDDS) 2024-10-31
  • Non-alcoholic beer / malt beverage (USDA): Beer, nonalcoholic — FDC 2710610, Food and Nutrient Database for Dietary Studies (FNDDS) 2024-10-31
  • Still water, for comparison: Water, tap — FDC 2710707, Food and Nutrient Database for Dietary Studies (FNDDS) 2024-10-31

The column the table does not have: alcohol, per 12 fl oz can

  • Regular beer: about 14 g of alcohol

    With 155 kcal and 12.8 g of carbohydrate, and 92% water by weight. USDA's regular beer is a generic US beer, not any one label.5

  • Light beer: about 11 g of alcohol

    About a fifth less alcohol than regular beer and about a third fewer calories, at 104 kcal. On a US label "light" is about calories; the 2.3% "light" beers in the Australian trials were low-alcohol beers, a different drink.5,8

  • Non-alcoholic beer / malt beverage: about 1.1 g of alcohol

    USDA's figures come from its "malt beverage, includes non-alcoholic beer" entry rather than non-alcoholic beer alone, so the 29 g of sugars a can may not match your label; check it. The trials' non-alcoholic beers reported carbohydrate, not sugars: 6 g per 100 g against 3 g for the Dutch pilsner, and 26 g against 12.64 g per 350 mL for the Chilean lager, about twice their alcoholic versions.5,6,12

Your can

What a can of beer holds, counted

Pick a beer and a size to see the water, calories and sugar it carries by USDA's figures. The share-of-goal bar is the same one every drink page uses; for beer, read it as arithmetic rather than a target.

mL

355 mL · 12 fl oz

355 mL of beer, regular delivers

331mL of water

11.2 fl oz · 92% water by weight

The NHS list of drinks that count toward daily fluid intake does not mention alcohol.13

Calories
155kcal
Sugars
0g
Protein
1.7g
Sodium
14mg
Potassium
97mg
Calcium
14mg

Water Goose has no alcohol preset, so none of these can be logged in the app — and nothing on this page is a reason to drink one.

Composition from USDA FoodData Central, converted through each drink’s density.5 Work out your daily goal

Questions

Beer, wine and hydration, question by question

Does beer dehydrate you?

Less than its reputation suggests, but it depends on the strength and on when you drink it. At rest, a litre of lager was not measurably different from a litre of water: a hydration index of 0.99 against water's 1.00. After exercise it is a different story: men who replaced their sweat loss with 4.6% beer produced 1,218 mL of urine over three hours, against 774 mL when they drank the same volume of water. In older men given 30 g of alcohol, 5% beer did not raise urine output while wine and spirits briefly did, and nothing differed at 24 hours. On what it calls limited data, NASEM concludes that alcohol's effect on urine appears to be transient, with no appreciable fluid loss over a day.1,4,3,2

Does beer hydrate you?

It carries water, and at rest a litre of lager was no different from a litre of water: USDA's regular beer is 91.96% water, and in the one trial that put beer through the hydration index, lager scored 0.99 against water's 1.00. After exercise, full-strength beer is a poor way to rehydrate: men who replaced their sweat loss with 4.6% beer passed 1,218 mL of urine over three hours, against 774 mL with water. Water Goose has no alcohol preset, and nothing on this page is a reason to drink beer to hydrate.5,1,4

Can beer count toward your daily water intake?

Water Goose has no alcohol preset, so the app does not log beer at all, and this page does not suggest counting it. By composition, USDA's regular beer is 91.96% water, so a 12 fl oz can carries roughly 330 mL of it, and at rest a litre of lager was not measurably different from a litre of water (0.99 against 1.00). But the NHS list of drinks that count toward daily intake — water, lower-fat milk and sugar-free drinks, including tea and coffee — does not mention alcohol, and every can of that water comes with about 14 g of it.5,1,13

Is non-alcoholic beer hydrating?

As far as the trials go, no different from water. After a mild sweat, non-alcoholic beer kept 36% of what was drunk over five hours against 34% for water, a difference that was not significant, and in older men it left the same urine output as 5% beer. What it swaps the alcohol for is carbohydrate: USDA's malt-beverage entry (which includes non-alcoholic beer) lists 8.05 g of sugars per 100 g and 0.3 g of alcohol, and the non-alcoholic beer in the Dutch trials carried 6 g of carbohydrate per 100 g against 3 g for the pilsner beside it.6,3,5

Does light beer dehydrate you less?

No trial used a US-branded light beer, but by USDA's figures a typical US light beer is about 4% alcohol by volume (3.1 g per 100 g, against 3.9 g, about 5%, for regular beer), with about a third fewer calories. That is the strength of the 4% beer in Hobson 2010, which raised urine output in well-hydrated men but not significantly in dehydrated ones. The "light" beers in the Australian trials were 2.3% low-alcohol beers, weaker than USDA's typical US light beer: with 25 mmol/L of added sodium, one left 1,477 mL of urine after exercise against 2,175 mL for a 4.8% beer. A follow-up trial also found that adding more salt to light beer did more for fluid retention than trimming its alcohol from 3.5% to 2.3%.5,9,8,14

Does wine dehydrate you more than beer?

Only briefly, and not clearly. In the one trial that compared them, older men given 30 g of alcohol with lunch, wine (13.5%) and spirits (35%) raised four-hour urine output against their alcohol-free versions, while 5% beer did not. But when the extra urine from each drink was compared directly, the differences were not significant, and by 24 hours none differed from its control. The beer also came with far more fluid: 30 g of alcohol meant 750 mL of beer against 279 mL of wine. The European Hydration Institute funded the trial with a contribution from the Dutch Beer Institute, which employed three of its authors.3

Is beer a good drink after a run or a workout?

Not as the thing you rehydrate with. When dehydrated men replaced their sweat loss with 4.6% beer, they produced 1,218 mL of urine over three hours against 774 mL with water, and their reaction time was slower than after a low-alcohol beer. NATA's position statement says drinks of 4% alcohol or less do not dehydrate active people, but that stronger ones should be discouraged for fluid replacement — though the trial it cites for the 4% figure found 4% beer raised urine output in well-hydrated men. In one trial, up to 660 mL of beer followed by as much water as the men wanted did no worse than water alone — but most of what they drank was water, and a beer and health information centre part-funded it.4,10,9,15

Which beer is the most hydrating?

On the trials, the one with the least alcohol and the most sodium. After a mild sweat, non-alcoholic and 2% beer both kept 36% of what was drunk, level with water, and of four light and mid-strength beers, the 2.3% beer with 50 mmol/L of added sodium left the least urine: 1,450 mL against 1,986 mL for a 3.5% beer. Ordinary beers carry very little sodium — 0.6 to 4 mmol per litre in the studies here, against 21 in the sports drink of the hydration index trial. None of this makes beer a rehydration drink.6,14,12,1

Will drinking water with beer stop a hangover?

Probably not by much. A 2024 review found that, in survey data, drinking water during or straight after alcohol had only a modest effect on the next day's hangover, and the amount of water drunk during a hangover was not related to any change in how bad it felt. Its authors conclude that a hangover and dehydration are separate after-effects that happen together. An earlier review found that dehydration markers, including vasopressin, did not track hangover severity. Water will not undo one.16,17

The alcohol trials

Does beer rehydrate you after exercise?

Most beer research asks a different question from the index: not what happens when a rested person drinks a litre, but what happens when someone who has just sweated out about 1-2% of their body weight tries to replace it with beer. Those results are a different measurement and do not share a scale with the index. Five of the trials below are post-exercise; two, including the only one in older men, are not. Every one is small — 6 to 20 men — and two have ties to the Dutch Beer Institute, named on their cards.

  • After exerciseUrine outputDifferent protocol

    After exercise, beer with up to 2% alcohol rehydrated like the alcohol-free version, and 4% slowed recovery (Shirreffs 1997)

    7

    After exercise, the alcohol-free beer with up to 2% alcohol added rehydrated as well as the alcohol-free version; at 4%, blood and plasma volume recovered more slowly.

    Method, results and caveats

    6 healthy, habitually active men aged 36 ± 9. Body-mass loss 2.01 ± 0.10%; drank 2212 ± 153 mL (150% of the loss) over 60 min; 6-h urine.

    What each group drank in Shirreffs 1997, and what was measured
    Alcohol-free beer, alone or with 1, 2 or 4% alcohol added6-h urine did not differ between drinks (P=0.307), though it tended to rise with the alcohol. With 4% alcohol, peak urine flow came later (P=0.024) and blood and plasma volume recovered more slowly. Plasma vasopressin did not differ between drinks at any time; only after the 4% drink did it fall significantly below its pre-exercise level.
    • — n=6. The lower fraction of fluid retained with 4% alcohol only approached significance.
  • After exerciseUrine outputDifferent protocol

    After a mild sweat, 5% beer produced more urine than the sports drink in the first hour, but by five hours no drink differed (Wijnen 2016)

    6

    Non-alcoholic and 2% beer rehydrated about as well as water; 5% beer produced more urine than the sports drink in the first hour.

    Method, results, caveats and funding

    11 men. 1% body-mass loss; drank 100% of the loss (736 ± 105 mL); 5-h urine. Energy and carbohydrate per 100 g; sodium per litre.

    What each group drank in Wijnen 2016, and what was measured
    Non-alcoholic beerAmstel 0.05-h urine 462 ± 241 mL; retention 36%.
    Low-alcohol beer (2%)Lingen's Blond5-h urine 507 ± 288 mL; retention 36%.
    Beer (5%)Amstel Pilsner5-h urine 580 ± 188 mL; retention 21%. Urine in the first hour 299 ± 143 mL vs 105 ± 67 mL for the sports drink (p<0.01); not significantly different from water or the other beers.
    Sports drinkIsostar Hydrate & Perform, lemon5-h urine 444 ± 240 mL; retention 42%.
    Waterreference5-h urine 478 ± 202 mL; retention 34%.

    Funding: Funded by a European Hydration Institute graduate research grant, with a financial contribution from the Dutch Beer Institute; the first author joined the Dutch Beer Institute during submission.

  • After exerciseUrine outputDifferent protocol

    Adding more salt to an already-salted light beer did more for fluid retention than trimming its alcohol (Desbrow 2015)

    14

    Urine was lowest with the light beer carrying the most added sodium.

    Method, results and caveats

    12 men. Body-mass loss 2.03 ± 0.19%; drank 150% of the loss over 1 h; light beer (2.3%) with 25 or 50 mmol/L added sodium, or mid-strength beer (3.5%) with 0 or 25 mmol/L; total urine.

    What each group drank in Desbrow 2015, and what was measured
    Light beer + 50 mmol/L sodiumUrine 1450 ± 183 mL.
    Light beer + 25 mmol/L sodiumUrine 1796 ± 284 mL.
    Mid-strength beer + 25 mmol/L sodiumUrine 1786 ± 373 mL.
    Mid-strength beerUrine 1986 ± 304 mL.
    • — Abstract only.
  • After exerciseUrine outputDifferent protocol

    After exercise, a 2.3% beer with added salt kept more fluid than a 4.8% beer (Desbrow 2013)

    8

    Full-strength beer produced much more urine than low-alcohol beer with added sodium, which gave the best net fluid balance.

    Method, results and caveats

    7 men. About 1.96% body-mass loss; drank 150% of the loss over 1 h; urine over 4 h.

    What each group drank in Desbrow 2013, and what was measured
    Light beer (2.3%) with 25 mmol/L added sodiumUrine 1477 ± 485 mL; net fluid balance -1.02 ± 0.35 kg.
    Full-strength beer (4.8%)Urine 2175 ± 372 mL; net fluid balance -1.59 ± 0.32 kg.
    Full-strength beer with 25 mmol/L added sodiumUrine 2101 ± 482 mL; net fluid balance -1.64 ± 0.28 kg.
    • — Abstract only; n=7.
    • — A fourth arm, 2.3% beer without added sodium, is not reported in the abstract.
  • After exerciseUrine outputDifferent protocol

    Rehydrating with 4.6% beer produced more urine than water or a low-alcohol beer (Flores-Salamanca 2014)

    4

    Rehydrating with 4.6% beer produced more urine than low-alcohol beer or water, and slower reaction time than the low-alcohol beer (the difference from water was not significant).

    Method, results and caveats

    11 men. 2.12% body-mass loss; replaced 100% of the loss (about 1.6 L) in 1 h; urine over 3 h.

    What each group drank in Flores-Salamanca 2014, and what was measured
    Beer, 4.6%Urine 1218 ± 279 mL. Peak blood alcohol 0.857 g/L.
    Low-alcohol beerUrine 745 ± 313 mL (p=0.007 vs beer).
    WaterreferenceUrine 774 ± 304 mL (p=0.043 vs beer).
    • — Abstract only.
  • At restUrine outputDifferent protocol

    A litre of 4% beer made well-hydrated men pee more than alcohol-free beer, but not dehydrated men (Hobson 2010)

    9

    Beer produced more urine than alcohol-free beer in well-hydrated men (P<0.001); when they were already dehydrated the difference was smaller and not significant (P=0.057).

    Method, results and caveats

    12 men. 1 L of 4% beer vs alcohol-free beer, drunk when euhydrated and after 1.9% body-mass loss; 4 h.

    What each group drank in Hobson 2010, and what was measured
    Beer, 4% alcoholUrine 1279 ± 256 mL when euhydrated; 261 ± 138 mL when hypohydrated.
    Alcohol-free beerUrine 1121 ± 148 mL when euhydrated; 174 ± 61 mL when hypohydrated.
    • — Abstract only.
  • At restUrine outputDifferent protocol

    In older men, wine and spirits briefly raised urine output; 5% beer did not (Polhuis 2017)

    3

    Over 4 h, wine (effect size 0.25, p<0.003) and spirits (0.18, p<0.001) briefly raised urine output against their controls; beer did not (-0.02, p>0.70).

    Method, results, caveats and funding

    No drink changed 24-h urine output.

    20 men aged 60-75, euhydrated, on a standardised diet. 30 g alcohol per alcoholic drink, with an equal volume of its non-alcoholic counterpart; cumulative urine at 4 and 24 h. Energy and carbohydrate per 100 g; sodium per litre.

    What each group drank in Polhuis 2017, and what was measured
    BeerAmstel PilsnerUrine 829 ± 217 mL at 4 h; 2459 ± 252 mL at 24 h.
    Non-alcoholic beerAmstel 0.0Urine 836 ± 316 mL at 4 h; 2435 ± 660 mL at 24 h.
    Red wineAH MerlotUrine 536 ± 192 mL at 4 h; 2028 ± 252 mL at 24 h.
    Non-alcoholic wineUrine 504 ± 130 mL at 4 h; 2163 ± 297 mL at 24 h.
    SpiritBols jeneverUrine 471 ± 189 mL at 4 h; 1846 ± 276 mL at 24 h.
    WaterreferenceUrine 450 ± 114 mL at 4 h; 1918 ± 470 mL at 24 h.
    • — Older men only; drink volumes differ between drink types.
    • — Three authors were employed by the Dutch Beer Institute.

    Funding: Funded by the European Hydration Institute, with a financial contribution from the Dutch Beer Institute; three authors (Polhuis, Wijnen, Sierksma) were employed by the Dutch Beer Institute while the study was run and written up.

Two more trials, each on a protocol of its own

  • Jiménez-Pavón 2015: up to 660 mL of beer, then water, did no worse than water

    Sixteen active men ran for up to an hour at 35 °C, losing about 2.4% of their body mass, then drank either water as they liked or up to 660 mL of 4.5% beer followed by water as they liked. Fluid balance and urine output did not differ. Most of what they drank was water, which diluted the alcohol to about 1.8% of the total, and the trial was part-funded by a beer and health information centre.15

  • Castro-Sepúlveda 2016: non-alcoholic beer before exercise

    Seven male footballers drank 0.7 L of water, 4.6% beer or non-alcoholic beer 45 minutes before a 45-minute run. Plasma sodium fell after water (−3.9%) and beer (−3.7%) but not after the non-alcoholic beer, and plasma potassium rose 8.5% after beer. A small trial of blood electrolytes, not of retention, and the authors report no funding.12

Mechanism

Why does alcohol make you pee more?

Does alcohol dehydrate you? It makes you pee more for a few hours — more with stronger drinks and when you are well hydrated to begin with, much less when you are already short of water — and in the trials here the difference was gone within a day, which is also NASEM's tentative reading of the limited data. Why it happens is less settled than the usual one-line answer.

  • Moderate evidenceOther

    The usual explanation is that ethanol suppresses vasopressin release, and NASEM states this. But two post-exercise trials that measured vasopressin found no difference between drinks of different alcohol content, which Polhuis 2017 takes as a sign other mechanisms are involved.3

    Caveat: Only Shirreffs 1997 compared alcohol with no alcohol, and in it vasopressin fell significantly below its pre-exercise level after the 4% drink alone. Desbrow 2015 compared 2.3% and 3.5% beers only.

  • Moderate evidenceRandomised trial

    One litre of 4% beer produced more urine than alcohol-free beer when drinkers were well hydrated, but the difference was smaller and not significant when they were already dehydrated.9

    12 men. Euhydrated urine 1279 ± 256 vs 1121 ± 148 mL (P<0.001). Hypohydrated (1.9% body mass lost) 261 ± 138 vs 174 ± 61 mL (P=0.057). Serum osmolality at 1 h 303 and 298 vs 290 and 284 mosmol/l.

    Caveat: Abstract only.

  • Weak evidenceRandomised trial

    A large alcohol dose raised urine output for about 3 hours, then caused overnight water retention. The next morning, drinkers held back far more of a water load.18

    8 healthy men; ethanol 1.2 g/kg over 3 h vs fruit juice. Diuresis in the first 3 h, antidiuresis from midnight to 6 AM. Morning water load of 20 mL/kg: retention 44 ± 6% after alcohol vs 12 ± 4% control (p<0.05). Plasma vasopressin was not different during the diuresis but was higher from 10 PM to 6 AM.

    Caveat: Abstract only; n=8; a very high dose.

  • Moderate evidenceGuideline

    NATA says alcohol inhibits vasopressin release. Drinks above 2% alcohol reduce fluid retention during rehydration, drinks up to 4% do not dehydrate active people, and stronger drinks should be discouraged for fluid replacement.10

    Above 2% alcohol reduces retention; up to 4% does not dehydrate; above 4% facilitates excessive diuresis. Recommendation 21 is graded SOR B.

    Caveat: NATA's 4% statement cites Hobson 2010, which found 4% beer did raise urine output in well-hydrated men (P<0.001); only in dehydrated men was the effect not significant. Its 2% statement cites Shirreffs 1997, where six-hour urine did not differ significantly between 0 and 4% drinks.

  • Moderate evidenceReview

    Hangover and dehydration look like separate after-effects that happen together. Dehydration effects were usually mild and short-lived, drinking water while drinking alcohol gave only modest prevention, and drinking water during a hangover did not relieve it.16

    Caveat: Abstract only, and based largely on survey data from the same research group.

  • Moderate evidenceReview

    Blood and urine markers, including hormones, electrolytes, glucose and dehydration markers such as vasopressin, were not significantly correlated with hangover severity. Immune factors were the most convincing correlate.17

    Caveat: Abstract only.

How concentrated these drinks actually are

Osmolality is what decides how fast a drink leaves the stomach and how water moves in the gut. Blood sits at roughly 275–295 mOsm/kg19. Drinks near that range empty quickly; concentrated ones sit far above it.

Measured osmolality of the drinks on this page
DrinkOsmolalitySpreadn
Beer, alcoholic20EichhofABV not given. Ethanol strongly raises measured osmolality.1,047mOsm/kg——
Beer, 4.6% ABV12CristalPer 350 mL: 153 kcal, 12.64 g carbohydrate, Na 14 mg, K 96 mg.997mOsm/kg——
Beer, non-alcoholic (0%)12CristalPer 350 mL: 110 kcal, 26 g carbohydrate, Na 32 mg, K 104 mg.323mOsm/kg——
Beer, non-alcoholic20ClausthalerLabelled non-alcoholic; no ABV is given in the source.275mOsm/kg——

What the hormone measurements actually show

The vasopressin explanation is the textbook one — NASEM and NATA both state it — but trials that measured the hormone are messier. After exercise, one trial found plasma vasopressin no different whether the same beer carried 0, 1, 2 or 4% alcohol, though only after the 4% drink did it fall significantly below its pre-exercise level. Another found no difference in vasopressin or aldosterone between 2.3% and 3.5% beers carrying 0 to 50 mmol/L of added sodium. After a large alcohol dose, a third found vasopressin no different during the hours of extra urine, and higher only later, during the overnight swing back to holding water.2,10,7,14,18

Why the beers in that table look so concentrated

The gap between the alcoholic and alcohol-free versions is the alcohol: ethanol strongly raises measured osmolality, and the non-alcoholic Chilean lager carried twice the carbohydrate of the 4.6% one yet measured 323 against 997 mOsm/kg. Osmolality is a reading of concentration, not a verdict on hydration — the lager in the index trial measured 774 mmol/kg and was still not measurably different from water.20,12,1

Receipts

Sources and how we compiled this

Where the composition comes from

U.S. Department of Agriculture, Agricultural Research Service. FoodData Central. Built 2026-09-15 from the published CSV releases, never hand-typed.

  • Food and Nutrient Database for Dietary Studies (FNDDS) · 2024-10-31
  • — Drinks and prepared foods use FNDDS (foods and drinks as consumed) whenever FNDDS has a code for the item.
  • — Raw produce and dairy foods use Foundation Foods when the entry is current (listed in foundation_food.csv), stands for the food generally rather than one cultivar or colour, and reports water, energy and potassium, plus fiber for plant foods. Otherwise SR Legacy.
  • — A Foundation pick with no household portions uses the portions of the SR Legacy entry for the same food (portionsSource).
  • — Fluid milks use FNDDS, whose composition matches the Foundation analyses (crossCheck) and which has consistent drink portions.
  • — SR Legacy fills any remaining gap. No proxy is used where USDA has no sensible entry (see missing).

What this evidence cannot tell you

  • — The Beverage Hydration Index measures short-term retention, not 24-h hydration: for each person it is urine after still water divided by urine after the test drink, anchored 2 h after drinking 1 L over 30 min.
  • — Most participants were young, healthy, euhydrated, fasted, rested men given a single 1 L dose. Older adults retain more water and respond differently.
  • — Post-exercise retention percentages come from dehydrated people drinking 100-150% of the body mass they lost. They are not comparable to BHI values and must not share a scale with them.
  • — Clarke 2019 reports mean ± SEM while most studies report SD, so spreads are not directly comparable.
  • — No resting BHI data were found for soup, smoothie, lemonade or coconut water. Energy-drink evidence comes from one modified-protocol study. The only hydration-index data for soda are cola and diet cola in Maughan 2016; the other soda studies cited (Grandjean 2000 over a day, Chapman 2019 during exercise in heat, García-Arroyo 2016 in rats) measured different outcomes.
  • — Many of these studies are industry funded: the European Hydration Institute, Entrinsic, Dairy Management, Nuun, Coca-Cola, Buoy, Lingtea, QCK, the Almond Board, 8 POiNT, VitaCoco, Liquid I.V., Innate-Essence, ITO EN, the Dutch Beer Institute, the Centro de Información Cerveza y Salud and ISIC all appear as funders.
  • — Commercial formulations change over time. Compositions are as measured or labelled at the time of each study and are not current labels.

Who paid for the research

Hydration research is heavily industry funded. That does not make a study wrong, but you should know who paid before you weigh it. Water Goose took no money from anyone named here, and no brand saw this page before it went up.

  • — Maughan 2016: Funded by a grant from the European Hydration Institute (EHI). Prof Maughan chairs the EHI Scientific Advisory Board (not the Institute itself); Dr Watson has also received EHI funding.
  • — Polhuis 2017: Funded by the European Hydration Institute, with a financial contribution from the Dutch Beer Institute; three authors (Polhuis, Wijnen, Sierksma) were employed by the Dutch Beer Institute while the study was run and written up.
  • — Wijnen 2016: Funded by a European Hydration Institute graduate research grant, with a financial contribution from the Dutch Beer Institute; the first author joined the Dutch Beer Institute during submission.
  • — Jimenez-Pavon 2015: Partially supported by the Centro de Información Cerveza y Salud (a beer and health information centre).
  • — Mackus 2024: Authors declare industry ties: one is a part-time Nutricia Research employee, and others have consulted for or held grants from companies including Red Bull, Sen-Jam Pharmaceutical and Danone.

References

Every number on this page points at one of these.

  1. 1

    Maughan RJ, Watson P, Cordery PAA, Walsh NP, Oliver SJ, Dolci A, Rodriguez-Sanchez N, Galloway SDR. A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index. Am J Clin Nutr 2016;103(3):717-723.

    StudyRead: full textOpen source

    Funding: Funded by a grant from the European Hydration Institute (EHI). Prof Maughan chairs the EHI Scientific Advisory Board (not the Institute itself); Dr Watson has also received EHI funding.

    Read from the LJMU green open-access accepted manuscript (https://researchonline.ljmu.ac.uk/id/eprint/12468/); the publisher page was blocked. ISRCTN13014105.

  2. 2

    Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Chapter 4: Water. Washington, DC: The National Academies Press; 2005.

    GuidelineRead: full textOpen source

    Cite this directly for adequate intakes: Maughan 2016's introduction misstates the women's figure. On alcohol it concludes the diuresis is transient; it makes no explicit 'all drinks count equally' statement.

  3. 3

    Polhuis KCMM, Wijnen AHC, Sierksma A, Calame W, Tieland M. The Diuretic Action of Weak and Strong Alcoholic Beverages in Elderly Men: A Randomized Diet-Controlled Crossover Trial. Nutrients 2017;9(7):660.

    StudyRead: full textOpen source

    Funding: Funded by the European Hydration Institute, with a financial contribution from the Dutch Beer Institute; three authors (Polhuis, Wijnen, Sierksma) were employed by the Dutch Beer Institute while the study was run and written up.

  4. 4

    Flores-Salamanca R, Aragon-Vargas LF. Postexercise rehydration with beer impairs fluid retention, reaction time, and balance. Appl Physiol Nutr Metab 2014;39(10):1175-1181.

    StudyRead: abstractOpen source

  5. 5

    U.S. Department of Agriculture, Agricultural Research Service. FoodData Central (SR Legacy and Foundation Foods).

    DatasetRead: official pageOpen source

    Water content is not the same thing as a net hydration effect.

  6. 6

    Wijnen AH, Steennis J, Catoire M, Wardenaar FC, Mensink M. Post-Exercise Rehydration: Effect of Consumption of Beer with Varying Alcohol Content on Fluid Balance after Mild Dehydration. Front Nutr 2016;3:45.

    StudyRead: full textOpen source

    Funding: Funded by a European Hydration Institute graduate research grant, with a financial contribution from the Dutch Beer Institute; the first author joined the Dutch Beer Institute during submission.

  7. 7

    Shirreffs SM, Maughan RJ. Restoration of fluid balance after exercise-induced dehydration: effects of alcohol consumption. J Appl Physiol 1997;83(4):1152-1158.

    StudyRead: full textOpen source

  8. 8

    Desbrow B, Murray D, Leveritt M. Beer as a sports drink? Manipulating beer's ingredients to replace lost fluid. Int J Sport Nutr Exerc Metab 2013;23(6):593-600.

    StudyRead: abstractOpen source

  9. 9

    Hobson RM, Maughan RJ. Hydration status and the diuretic action of a small dose of alcohol. Alcohol Alcohol 2010;45(4):366-373.

    StudyRead: abstractOpen source

  10. 10

    McDermott BP, Anderson SA, Armstrong LE, et al. National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active. J Athl Train 2017;52(9):877-895.

    GuidelineRead: full textOpen source

  11. 11

    NHS. Drinking alcohol while pregnant.

    GuidelineRead: official pageOpen source

    Read 25 September 2026. States that if you are pregnant or planning to become pregnant you should not drink alcohol. Page last reviewed 13 March 2023; next review was due 13 March 2026, so the review is overdue.

  12. 12

    Castro-Sepulveda M, Johannsen N, Astudillo S, et al. Effects of Beer, Non-Alcoholic Beer and Water Consumption before Exercise on Fluid and Electrolyte Homeostasis in Athletes. Nutrients 2016;8(6):345.

    StudyRead: full textOpen source

    Beers were Cristal (Santiago, Chile) at 4.6% and 0% alcohol. The paper does not say whether drink values were measured or taken from labels.

  13. 13

    NHS. Water, drinks and hydration. Page last reviewed 17 May 2023.

    GuidelineRead: official pageOpen source

    Next review was due 17 May 2026, so the review is overdue as of September 2026.

  14. 14

    Desbrow B, Cecchin D, Jones A, Grant G, Irwin C, Leveritt M. Manipulations to the alcohol and sodium content of beer for postexercise rehydration. Int J Sport Nutr Exerc Metab 2015;25(3):262-270.

    StudyRead: abstractOpen source

  15. 15

    Jimenez-Pavon D, Cervantes-Borunda MS, Diaz LE, Marcos A, Castillo MJ. Effects of a moderate intake of beer on markers of hydration after exercise in the heat: a crossover study. J Int Soc Sports Nutr 2015;12:26.

    StudyRead: abstractOpen source

    Funding: Partially supported by the Centro de Información Cerveza y Salud (a beer and health information centre).

  16. 16

    Mackus M, Stock AK, Garssen J, Scholey A, Verster JC. Alcohol hangover versus dehydration revisited: The effect of drinking water to prevent or alleviate the alcohol hangover. Alcohol 2024;121:9-18.

    StudyRead: abstractOpen source

    Funding: Authors declare industry ties: one is a part-time Nutricia Research employee, and others have consulted for or held grants from companies including Red Bull, Sen-Jam Pharmaceutical and Danone.

  17. 17

    Penning R, van Nuland M, Fliervoet LA, Olivier B, Verster JC. The pathology of alcohol hangover. Curr Drug Abuse Rev 2010;3(2):68-75.

    StudyRead: abstractOpen source

  18. 18

    Taivainen H, Laitinen K, Tahtela R, Kilanmaa K, Valimaki MJ. Role of plasma vasopressin in changes of water balance accompanying acute alcohol intoxication. Alcohol Clin Exp Res 1995;19(3):759-762.

    StudyRead: abstractOpen source

  19. 19

    Sadowska A, Świderski F, Rakowska R, Waszkiewicz-Robak B, Żebrowska-Krasuska M, Dybkowska E. Beverage osmolality as a marker for maintaining appropriate body hydration. Rocz Panstw Zakl Hig 2017;68(2):167-173.

    StudyRead: full textOpen source

    Polish market products. This is the source of the 275-295 mOsm/kg range (it describes the isotonic drinks tested), not Maughan 2016.

  20. 20

    Mettler S, Rusch C, Colombani PC. Osmolality and pH of sport and other drinks available in Switzerland. Schweiz Z Sportmed Sporttraumatol 2006;54(3):92-95.

    StudyRead: full textOpen source

    Products bought November 2005; freezing-point osmometer, duplicate readings.

How we compiled this

Composition comes from USDA FoodData Central — FNDDS 2024-10-31 for all three beers and for water — converted to per-can amounts through each item's USDA density. The hydration index value comes from the 2016 trial that defined the index, where lager's mean and standard deviation appear only in a figure and are marked approximate. The alcohol trials were read from their abstracts and, where open, their full texts. Industry money runs through this evidence: the European Hydration Institute funded the index trial, the Dutch post-exercise trial and the older-men trial; the Dutch Beer Institute contributed to the last two and employed three of the older-men trial's authors; and a beer and health information centre part-funded the Spanish trial. No one paid for or reviewed this page.5,1,6,3,15

This page describes what studies measured in healthy adults. It is general wellness information, not medical advice, diagnosis or treatment. Fluid needs change with health conditions, medication and pregnancy — and some conditions require drinking less. Talk to a clinician about yours.

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