Does Alcohol Affect Muscle Growth? The Protein Synthesis Effect

So, you just had a great workout and you’re trying to decide whether drinking a glass or two of alcohol later is going to set back your fitness goals. No need to stress, we’re going to cover the effects of alcohol and fitness goals. This blog is going to cover some of the physiological effects of alcohol on muscle growth and offer solutions to help balance alcohol intake with fitness goals. We’ll be covering the effects of alcohol on performance and muscle gain. After this, you can decide if one day or one week of drinking will affect muscle growth and fitness goals.

Alcohol or ethanol is a chemical found in beer, wine, and liquor. It’s produced by the fermentation of sugar or starches. While alcohol is not a macronutrient, meaning that our body doesn’t need it in large quantities to survive, it does provide calories like a traditional macronutrient (protein, carbohydrates, and fats). Alcohol produces 7 calories per gram consumed, research shows that energy from alcohol consumption is generally additive to energy from other dietary sources.[1] People typically consume calories above their baseline levels when they consume alcohol, meaning these calories are added to someone’s diet in addition to the foods they'd normally eat. In the presence of ethanol, our bodies use alcohol as the preferred fuel preventing fat and to lesser degrees carbohydrates and protein from being oxidized.[2] In other words, when we consume alcohol our body’s first focus is on metabolizing this energy source before it can burn any other energy sources. Even though alcohol consumption tends to increase people’s daily caloric intake and it impairs fat burning, large cross-sectional research studies indicate that light-to-moderate alcohol intake is not associated with obesity. While heavy drinking is more consistently related to weight gain. [3,4]

Blood alcohol concentration will vary based on various factors including genetics, gender, body type, and type of alcohol consumed. In general, drinking on an empty stomach and drinking higher concentrations of alcohol per volume will increase blood alcohol levels to a greater extent. On an empty stomach, blood alcohol concentration peaks about an hour after consumption and then decreases linearly for the next four hours.[5] Alcohol is slowly absorbed by our stomachs, more rapidly absorbed by our small intestines, and about 90% of it is eliminated by our liver. Many of the detrimental health effects associated with any alcoholic drink are due to its metabolism and the metabolites produced.[6] Acetaldehyde as an example is a highly reactive metabolite of alcohol that causes nonspecific chemical modifications to proteins and nucleic acids.

While it’s generally agreed by researchers that alcohol negatively impacts performance, this is an area that hasn’t gotten a lot of research funding due to ethical implications. Despite this fact, from the existing literature on the topic, there’s enough cellular and animal research that should make athletes hesitant to think alcohol would benefit performance or recovery.[7]

Alcohol has metabolic, cardiovascular, thermoregulatory, and neuromuscular effects that would likely negatively impact exercise performance.[8] Alcohol, even at low levels impairs reaction time, and coordination, and impacts the metabolism of nutrients that fuel exercise like carbohydrates.[9] While long term heavy chronic alcohol consumption would likely negatively impact performance by affecting the cardiovascular system, contributing to nutrient deficiencies, muscle loss, decreased testosterone production, and impaired coordination. Research also indicates that alcohol consumption results in a higher incidence of injury in athletes and the effect of hangovers have been reported to decrease athletic performance.[10]

Research on alcohol intake and muscle growth indicates that while alcohol intake may not impair muscle recovery function it does impair cellular signals that promote muscle growth, especially in men. In one study, researchers had men and women ingest alcohol or a placebo post-exercise and they found that alcohol ingestion reduced muscle protein synthesis rates and mTORC activation in men but not women.[11] This is consistent with other research that shows that the negative effects of alcohol appear to affect men to a greater extent than women, as observed by decreased levels of free testosterone and luteinizing hormone while cortisol levels increase. [12,13]

A different study was done on recreationally trained subjects that had them consume either low or high doses of alcohol after exercise. The researchers observed that neither the low nor high dose of alcohol had an adverse effect on the recovery of muscle function after exercise, however, they noted that alcohol intake increased cortisol levels and reduced the testosterone/cortisol ratio which suggests potential negative long-term effects.[14]

Most data on alcohol intake indicates that it impairs muscle protein synthesis, even when in the presence of anabolic stimuli like exposure to nutrients or resistance training. This suppression on muscle protein synthesis is relatively long lasting with acute alcohol intake being observed to impair muscle protein synthesis rates for over 13 hours post consumption, with effects lasting even after alcohol has been cleared from one’s system.[15] A systematic review examined the effects of alcohol consumption on recovery following resistance training. The data showed that alcohol consumption following exercise did not impair muscle function but the effects on free testosterone, cortisol, and rates of muscle protein synthesis suggest long-term muscle growth adaptations may be impaired.[16] Basically, a drink or two after exercise won’t ruin all your gains but habitually consuming alcohol (especially in high amounts) likely will make your muscle building goals difficult.

Alcohol & The Effects on Nutrition / Balanced Eating

The biggest impact of alcohol related to nutrition and fitness goals is that it’s mostly an empty calorie source. Alcohol provides the body with an extra source of calories but is typically lacking in beneficial nutrients compared to more nutrient-dense foods. Research shows that it’s possible to recover and rehydrate after exercise, however it’s not the best practice. In one study, scientists examined the effects of alcohol intake post-exercise on glycogen re-synthesis. Their conclusion was that the effects of alcohol intake post-exercise were more indirect, meaning that alcohol intake often displaces the intake of nutrients that are more optimal for recovery.[17] A study was done on rats supplied with oral leucine. The scientists observed that while oral leucine increased muscle protein synthesis rates in the animals to similar magnitudes, the increase in protein synthesis in the alcohol group was insufficient to overcome the suppressive effects of alcohol intake.[18] Similarly, a study in physically active males found that when alcohol was consumed alongside protein post-exercise muscle protein synthesis rates were reduced compared to the groups that consumed protein on its own.[19] Meanwhile, a study on the effects of alcohol consumption on fluid and electrolyte replenishment post-exercise showed that while alcohol has a diuretic effect, beverages that are alcohol-free or containing alcohol up to 2% could promote rehydration. However, drinks containing 4% alcohol showed a tendency to delay the recovery process.[20]

Alcohol & The Effects on Sleep

Sleep plays an important role in recovery and contributes to performance in our subsequent workouts. Research on the effects of alcohol consumption and sleep indicates that it’s associated with poor sleep quality and sleep duration. These negative effects of alcohol consumption and sleep quality were seen more significantly in men than women, although researchers suspected that it could be related to their respective rates of alcohol consumption.[21]