Alcohol can negatively impact protein synthesis in a few ways. First, by disrupting your sleep. Alcohol increases deep sleep and decreases REM; REM sleep is where testosterone peaks, so it’s pretty darn important for optimal muscle protein synthesis. A lot of people self-medicate with alcohol to go to sleep because it makes falling asleep easier. And that’s the thing with alcohol and sleep: even if it feels like you’re sleeping okay after a few, because, hey, you fell asleep in like five minutes, you’re probably still not sleeping as well as you could. It’s sneaky.
Second, alcohol is potentially really bad for the gut. Ethanol directly increases permeability in epithelial cells, for one. And you know how our livers metabolize alcohol into the far more toxic acetaldehyde before breaking down and excreting it completely? Gut bacteria themselves metabolize alcohol into acetaldehyde, which can also cause tight junctions to grow more leaky. If your gut’s leaky, you’re not absorbing all the nutrients you eat – nutrients you need to turn into muscle and support your training and recovery.
Third, alcohol is incredibly dehydrating. Some researchers even attribute the lion’s share of the hangover to extreme dehydration. The worst part of alcohol-induced dehydration is that you’re not just robbing yourself of water. You’re also peeing out tons of electrolytes and other minerals like magnesium, sodium, and potassium that play huge roles in maintaining the hormonal environment necessary for muscle protein synthesis.
Fourth, alcohol taken post workout can directly impair muscle protein synthesis, reducing the rate by almost 40%. That was binge drinking, or a stiff drink taken every thirty minutes. Drinking on a rest day could be less inhibitory than drinking immediately after a workout, but the recovery period continues on throughout the rest day and the potential for impairment exists.
All that said, two to three total drinks spread out through the week on rest days is probably fine. Two to three drinks every rest day might not be a good idea.
Still, you’re a competitive athlete. You might try a month of no alcohol whatsoever – not even on rest days – to see if your performance improves. I suspect it might offer a leg up on the competition. It’s certainly worth a shot. Consider it a personal challenge from me to you, Rocky. Let me know how it goes if you decide to do it.