Preliminary research shows that alcohol can impair protein synthesis, or the process that builds new muscle. In research done on rats published in the American Journal of Physiology, alcohol consumption was associated with a decrease in muscle weight and lean body mass. The researchers explain that alcohol may affect the proteins that activate muscle growth.
What’s more, a separate study from Pennsylvania State University College of Medicine found that alcohol decreased the production of human growth hormone, a key part of the muscle repair and growth process, by up to 70%. Experts note that both of these studies were done with a large amount of alcohol administered to animals, so a few drinks may not have the same effect.