Alcohol and Muscle Growth: What the Studies Really Show

Barely any topic around alcohol and strength training gets answered with a single number as often as this one:

37 percent less muscle growth.

The number does come from a study. The problem is only what got made of it.

The participants did not drink one beer after training but 1.5 g of alcohol per kilogram of body weight — around twelve standard drinks on average. And what was measured was not actual muscle gain over weeks or months, but muscle protein synthesis over a few hours.

So the study answers an interesting question.

Just not necessarily the one most lifters are asking.

What happens with one beer after training? With two glasses of wine at the weekend? Or if you go out occasionally but otherwise train and eat normally?

That is exactly where the data gets surprisingly thin.

Alcohol and muscle growth in two minutes

The research comes out very differently depending on the question:

Question	What we currently know
A large amount of alcohol straight after training	muscle protein synthesis can drop considerably
One to a few drinks and long-term muscle growth	barely any direct data
Strength and performance after alcohol	results inconsistent, studies mostly small
Sleep	REM sleep can be altered at lower doses already
Calories	alcohol supplies 7 kcal per gram
Long-term health	no amount known to be free of health risk

The most important distinction is between direct evidence and extrapolation.

That a large amount of alcohol after training reduces muscle protein synthesis has been measured.

But you cannot calculate from that how many grams of muscle a beer costs you.

And that distinction gets lost in a lot of fitness articles.

Where the famous 37 percent comes from

The most-cited study on the topic comes from Parr and colleagues, from 2014.

Eight men completed a combination of strength training and intense cycling. Afterwards, in different experimental conditions, they received:

• protein without alcohol
• alcohol plus protein
• alcohol plus carbohydrate

The alcohol dose was 1.5 g per kilogram of body weight.

For an 80-kg man that would be:

120 g of pure alcohol.

For comparison:

Drink	roughly pure alcohol
0.3 l of beer at 5 %	12 g
0.5 l of beer at 5 %	20 g
0.125 l of wine at 12 %	12 g
0.2 l of wine at 12 %	19 g

So 120 g corresponds to roughly six large beers, or around ten small standard glasses. In the original study it came to about twelve standard drinks on average, because a different standard-drink definition was used there.

The result:

Condition	Muscle protein synthesis vs. protein alone
Alcohol + protein	−24 %
Alcohol + carbohydrate	−37 %

So the frequently quoted figure of 37 percent is real.

But it needs context.

First, a very high amount of alcohol was used.

Second, the decline was smaller when protein was taken at the same time.

And third, what was measured was muscle protein synthesis — not actual muscle gain.

Muscle protein synthesis describes part of the muscle protein remodelling process over a limited period. It is biologically relevant, but it does not translate one to one into a percentage figure for later muscle growth.

So:

37 percent less muscle protein synthesis for a few hours

does not automatically become:

37 percent less muscle growth.

What we do not know about small amounts

This is where the most important research gap sits.

The question most lifters actually care about is more like:

What happens to my muscle growth if I occasionally have one or two beers?

There is no precise answer to that yet.

A 2023 review states explicitly that neither the long-term influence of moderate alcohol consumption on training adaptations in healthy people, nor a clear dose at which muscle growth becomes measurably impaired, is known.

That means two things at once:

There is no good evidence that a single beer noticeably ruins your muscle growth.

But:

There is equally no study from which you could conclude that, say, two drinks a week guarantee no effect at all.

Not studied means neither safe nor harmful.

To begin with it only means:

We do not know precisely.

Which is exactly why it is problematic to scale a linear effect for small amounts down from studies using 1.0 or 1.5 g/kg of alcohol.

If twelve drinks reduce muscle protein synthesis by a certain amount, it does not follow that one drink causes exactly one twelfth of that effect.

Biological responses do not necessarily run in a straight line.

What studies show on strength and performance

The effects on actual performance are less clear-cut than the muscle protein synthesis data.

A 2019 systematic review looked at twelve studies on alcohol after strength training. The amounts used sat roughly between 0.6 and 1.5 g/kg of body weight.

Across several of the measures examined, the papers found no consistent effect, including:

• maximal strength
• power
• strength endurance
• soreness
• perceived exertion

That sounds reassuring at first.

Many of those studies were very small, though. Frequently only eight to ten people took part.

At sample sizes like that, large differences can show up. Small or medium effects, by contrast, can easily go undetected.

So no statistically demonstrated difference does not automatically mean the effect is exactly zero.

A 2010 study, for instance, found greater strength losses after alcohol consumption. But the loading protocol used consisted of 300 maximal eccentric repetitions, deliberately designed to produce substantial muscle damage.

That is experimentally interesting.

It barely corresponds to a normal squat, bench press or deadlift session, though.

So the more sensible conclusion is:

There is no robust evidence for a large, reliably occurring direct loss of strength after moderate alcohol consumption. But the data is too sparse and too inconsistent to give a full all-clear.

What is probably more relevant at small amounts: sleep

For muscle growth, we lack good data precisely at low doses.

On sleep, we know more.

A 2025 systematic review with meta-analysis evaluated 27 studies on alcohol and sleep in healthy adults.

What emerged above all was a consistent effect on REM sleep:

• REM sleep started later
• REM sleep duration decreased
• higher alcohol doses tended to produce larger changes

One linguistic subtlety is decisive here.

The meta-analysis found changes already in studies assigned to the lower dose category of up to 0.5 g/kg.

That does not mean:

Sleep tips over at exactly 0.5 g/kg.

And converting it into a fixed number of glasses is problematic too.

At 0.5 g/kg, that comes to:

Body weight	pure alcohol
60 kg	30 g
70 kg	35 g
80 kg	40 g
95 kg	47.5 g

How many drinks that is then depends on glass size, alcohol content and the definition of a standard drink being used.

At 80 kg, 40 g would be roughly:

• two large beers of 0.5 l each at 5 %
• slightly more than three small German standard glasses at about 12 g of alcohol

So a fixed rule like “sleep suffers from two glasses onwards” would be too imprecise.

The defensible point is a different one:

Sleep architecture can be altered at considerably lower amounts of alcohol than the amounts used in the well-known muscle protein synthesis studies.

Why falling asleep faster does not automatically mean sleeping better

Alcohol is often perceived as a sleep aid.

That is not entirely made up.

At higher amounts, the time it takes to fall asleep can indeed shorten.

But sleep does not consist only of losing consciousness as fast as possible.

The different sleep stages serve different functions. If alcohol changes the onset or duration of REM sleep, a night can still look subjectively like normal sleep at first.

Which also explains why:

“I sleep great after two beers”

and

“Alcohol changes my sleep”

are not necessarily opposites.

Subjectively falling asleep and objective sleep architecture measure different things.

What night-time heart rate and HRV show

A large observational study examined 4,098 Finnish employees and combined alcohol reports with night-time heart rate data.

As the amount of alcohol rose, a physiological recovery score calculated from heart rate and heart rate variability got worse.

That supports the assumption that alcohol can affect night-time autonomic regulation.

What matters, though, is what that value does not mean.

A recovery score worse by, say, ten percentage points is not equivalent to:

• ten percent less muscle growth
• ten percent worse recovery
• ten percent less training performance

It is a specific, HRV-based measurement.

There is also a possible conflict of interest: three of the six authors worked at Firstbeat Technologies, whose measurement system was used for the analysis.

With more than four thousand participants the study is interesting all the same — its recovery score just should not be equated with muscle recovery.

Distance from bedtime or distance from training?

A common recommendation runs:

Do not drink alcohol for several hours after training.

There is no scientifically established rule in hours for that.

We have no good studies showing, for example:

• two hours’ distance from training
• four hours’ distance from training
• six hours’ distance from training

and deriving a clear threshold for muscle growth from it.

In practice, the current data argues more for keeping an eye on sleep and total amount.

For small amounts of alcohol, direct data on muscle growth is missing. Changes in sleep architecture, by contrast, have been observed at lower doses.

No exact clock time follows from that.

But a sensible practical reading does:

If you want to drink, less alcohol and more distance from sleep is probably more useful than clinging to an invented two- or four-hour rule after training.

Across several weeks: what training studies show

One of the few longer-running investigations had participants consume alcohol regularly over ten weeks while completing a HIIT program.

Men received 24 to 36 g of alcohol on weekdays, women 12 to 24 g.

Endurance performance improved similarly in all groups.

At first glance that sounds like a study of whether moderate alcohol consumption prevents training adaptations.

For muscle growth, though, it barely answers the question.

The training was predominantly interval work. What was measured included:

• endurance performance
• grip strength
• jump height

Muscle growth after strength training was not among the endpoints examined.

There is also the funding: the study was co-funded with just under 30,000 euros from the information centre of the Spanish brewing industry; a senior author had previously sat on its scientific advisory board.

That does not automatically make the results wrong.

But it is relevant context — particularly on a topic with strong commercial interests.

Calories, glycogen and testosterone

A few further claims circulate around alcohol in strength training.

Alcohol supplies a lot of calories

This point is comparatively uncomplicated.

Alcohol supplies about 7 kcal per gram.

Three large beers can therefore quickly contribute several hundred kilocalories — before snacks, fast food or larger portions come into it.

For muscle growth that is not automatically a problem.

While dieting, though, it can become relevant, because alcohol supplies comparatively many calories without being particularly filling.

So anyone wanting to lose fat should first treat alcohol like any other energy source:

It counts towards your calorie balance.

Alcohol does not simply block your glycogen stores

Glycogen gets oversimplified frequently too.

An older investigation from endurance research showed no simple mechanism along the lines of:

Alcohol prevents carbohydrate from being stored.

A substantial part of the problem arises more when alcohol displaces carbohydrate-rich food.

Anyone who drinks alcohol after a long endurance effort and takes in less carbohydrate as a result refills their stores less well.

That is something other than a direct, complete blockade of glycogen synthesis.

For normal strength training, this point is less central anyway than it is often made out to be.

Testosterone is not a muscle growth meter

High amounts of alcohol can cause hormonal changes.

But no specific muscle growth prediction should be derived from that too hastily.

Short-term fluctuations in testosterone, growth hormone or cortisol after a session do not reliably show how much muscle gets built weeks later.

The same problem is covered in more detail in the article on cortisol and strength training.

Particular caution is warranted with a frequently cited paper from 2014, according to which moderate alcohol consumption could raise testosterone. That review was retracted the same year because of excessive overlap with other texts.

Men and women are hardly studied equally well

Almost all studies on alcohol and strength training were conducted predominantly or exclusively with men.

Which creates a familiar problem:

The data frequently gets transferred to women even though it was barely collected there directly.

One of the few investigations including both sexes found differences in certain signalling pathways after alcohol and strength training: in men, a signal associated with muscle protein synthesis was suppressed more strongly than in women.

That is interesting.

But a single molecular finding is enough neither for an all-clear in women nor for the claim that alcohol impairs muscle growth only in men.

Long-term training studies are missing for that.

And regardless of training: alcohol is not healthy

Up to this point it has mainly been about the question:

What does alcohol do to training and muscle growth?

For long-term health, the evidence is clearer.

The International Agency for Research on Cancer lists alcoholic beverages as a Group 1 carcinogen.

That means:

There is convincing evidence that alcohol can cause cancer in humans.

The cancers associated with it include:

• mouth and throat cancer
• oesophageal cancer
• liver cancer
• bowel cancer
• breast cancer

The Group 1 classification is sometimes misunderstood.

Tobacco and asbestos are in that category too, for instance.

That does not mean a glass of wine causes the same risk as smoking or heavy asbestos exposure.

The IARC groups primarily describe how certain the carcinogenic effect is, not how large the risk is at a given exposure.

What became of the “healthy glass of red wine”

For decades, observational studies suggested that people with low alcohol consumption sometimes lived longer than complete abstainers.

Which gave rise to the idea:

A little alcohol might even be healthy.

The problem lies in possible systematic biases in such comparisons.

One of them is the composition of the non-drinker group.

If former drinkers who stopped because of illness, for instance, end up in a comparison group alongside lifelong abstainers, that group can look sicker on average.

On top of that come further differences between people with low alcohol consumption and abstainers that can never be fully adjusted away in observational studies.

A 2024 systematic evaluation compared more than a hundred cohort studies, also by their methodological quality.

The apparent health advantage of low alcohol amounts showed up above all in methodologically weaker studies.

In the better-controlled investigations, the clear advantage disappeared.

That is no proof that every single glass causes measurable harm to health.

But it argues against the older idea that small amounts of alcohol are health-promoting because of the alcohol itself.

What is officially recommended

The German Nutrition Society sharpened its assessment of alcohol considerably in 2024.

Its core statement:

There is no alcohol consumption free of health risk.

The DGE therefore recommends drinking no alcohol, or as little as possible.

That is different from saying every glass causes a large individual risk.

For communication purposes, the DGE distinguishes different risk bands:

Alcohol per week	Classification
under 27 g	low risk
27–81 g	moderate risk
over 81 g	high risk

At roughly 12 g of alcohol per small standard glass, the first band corresponds roughly to one or two small drinks per week.

The wording matters:

low risk does not mean risk-free.

So for people who do not drink alcohol, there is no health reason to start.

The German Centre for Addiction Issues likewise deliberately avoids a supposedly “safe” drinking amount. One reason is that specific thresholds are easily read as a recommendation or a guarantee.

What does that mean in practice for strength training?

A few sensible consequences follow from the overall picture.

One beer is not the 37 percent study

The well-known study with markedly reduced muscle protein synthesis used a very high amount of alcohol.

A single beer cannot be equated with it.

There is no credible percentage figure for how much muscle growth a drink costs you.

The more alcohol, the less reason for an all-clear

That small amounts are poorly studied does not mean the dose is irrelevant.

At very high amounts we see clearer effects on muscle protein synthesis, sleep and other physiological processes.

So if training and recovery are the priority, less is the more conservative choice.

Restraint makes sense before important training days

If a heavy squat, deadlift or other technically demanding session is due the next morning, alcohol can be unfavourable for a simple reason:

You want to sleep as well as possible and train recovered.

That needs no claim that every beer directly blocks muscle growth.

Do not fight bad form the next day

If you slept badly and familiar weights feel unusually heavy, you do not have to force a planned best.

Depending on your training plan, it can be more sensible to:

• train normally but somewhat more conservatively
• reduce volume
• postpone the heavy session

The point is not to build alcohol into your plan with a complicated special rule.

The point is to respond to your actual capacity.

While dieting, count the calories first

For fat loss, one of the most certain effects of alcohol is simultaneously the least spectacular:

7 kcal per gram.

If alcohol regularly consumes a large part of your calorie budget, that can affect the diet considerably more than a speculative small effect on muscle protein synthesis.

Conclusion

The question “is alcohol bad for muscle growth?” sounds simpler than the research can answer it.

At large amounts the direction is clear: a very high alcohol dose straight after training can reduce muscle protein synthesis considerably.

That is exactly where the well-known figure of 37 percent comes from.

For the amount many people actually care about — one beer, two glasses of wine or occasional drinking at the weekend — good long-term studies on muscle growth are missing.

That does not mean small amounts are guaranteed to be without consequence.

But it equally does not mean the results of twelve drinks can simply be scaled down to a single one.

On sleep the evidence is stronger. Alcohol can change sleep architecture at lower doses already, with the extent and the practical significance rising with the amount.

And for long-term health the situation is clearer than for muscle growth: no amount of alcohol is known to be free of health risk. Which is why the DGE recommends no alcohol, or as little as possible.

That leaves a sober answer:

On current data, an occasional drink cannot be quantified as a specific loss of muscle growth. The more and the more regularly you drink, the less speaks for it from the perspective of training, sleep and health.

So anyone deciding on a Friday evening between a beer and no beer needs no invented percentage figure for lost gains.

The research simply does not give us that number.

Further reading:

• Recovery in strength training
• Cortisol and strength training: myths vs. facts
• Nutrition for muscle growth
• How to measure training progress

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Sources

Funding is given for every source where it could be verified. For three older papers, the information was not freely accessible.

• Parr EB, Camera DM, Areta JL, et al. (2014). Alcohol ingestion impairs maximal post-exercise rates of myofibrillar protein synthesis following a single bout of concurrent training. PLoS ONE, 9(2):e88384. — Funded by the Australian Sports Commission; no conflicts of interest declared.
• Gardiner C, Weakley J, Burke LM, et al. (2025). The effect of alcohol on subsequent sleep in healthy adults: a systematic review and meta-analysis. Sleep Medicine Reviews, 80:102030. — No funding statement deposited in the university repository.
• Levitt DE, Luk HY, Vingren JL (2023). Alcohol, resistance exercise, and mTOR pathway signaling: an evidence-based narrative review. Biomolecules, 13(1):2. — Funded from Texas Tech University start-up funds; no conflicts of interest declared.
• Lakićević N (2019). The effects of alcohol consumption on recovery following resistance exercise: a systematic review. Journal of Functional Morphology and Kinesiology, 4(3):41. — No external funding; no conflicts of interest declared.
• Molina-Hidalgo C, De-la-O A, Dote-Montero M, et al. (2020). Influence of daily beer or ethanol consumption on physical fitness in response to a high-intensity interval training program. The BEER-HIIT study. Journal of the International Society of Sports Nutrition, 17:29. — Co-funded with €29,870 from the Centro de Información Cerveza y Salud (Spanish brewing industry); one author was formerly a member of its advisory board.
• Pietilä J, Helander E, Korhonen I, et al. (2018). Acute effect of alcohol intake on cardiovascular autonomic regulation during the first hours of sleep in a large real-world sample of Finnish employees. JMIR Mental Health, 5(1):e23. — Funded by TEKES (the state innovation agency); three of six authors employed at Firstbeat Technologies, whose device and analysis were used.
• Barnes MJ, Mündel T, Stannard SR (2010). Post-exercise alcohol ingestion exacerbates eccentric-exercise induced losses in performance. European Journal of Applied Physiology, 108(5):1009–1014. — Funding statement not freely accessible.
• Barnes MJ (2014). Alcohol: impact on sports performance and recovery in male athletes. Sports Medicine, 44(7):909–919. — Funding statement not freely accessible.
• Burke LM, Collier GR, Broad EM, et al. (2003). Effect of alcohol intake on muscle glycogen storage after prolonged exercise. Journal of Applied Physiology, 95(3):983–990. — Funding statement not freely accessible.
• Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB (2013). Alcohol and sleep I: effects on normal sleep. Alcoholism: Clinical and Experimental Research, 37(4):539–549.
• Stockwell T, Zhao J, Clay J, et al. (2024). Why do only some cohort studies find health benefits from low-volume alcohol use? A systematic review and meta-analysis of study characteristics that may bias mortality risk estimates. Journal of Studies on Alcohol and Drugs, 85(4).
• Retraction Note (2014): Alcohol consumption and hormonal alterations related to muscle hypertrophy: a review. Nutrition & Metabolism, 11:43. — Retracted by the editors on 24.09.2014.
• World Health Organization, Regional Office for Europe (2023): Classification of alcohol as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC).
• Deutsche Gesellschaft für Ernährung (2024): Position paper “Alkohol — Zufuhr in Deutschland, gesundheitliche sowie soziale Folgen und Ableitung von Handlungsempfehlungen”. Replaces the previous reference value for alcohol intake.
• Deutsche Hauptstelle für Suchtfragen (2023): Recommendations on handling alcohol from the scientific advisory board — dispensing with limits and thresholds in risk communication.
• Canadian Centre on Substance Use and Addiction (2023): Canada’s Guidance on Alcohol and Health.
• Bundeszentrale für gesundheitliche Aufklärung: definition of a standard glass (drugcom.de).