Actually, there is a little protein in beer - the Bud Light sitting in front of me has 0.9 grams of protein. It would take an awfully large amount of them to get what I need, plus its incomplete protein, I'm sure.
Carb-wise, it has 6.6 grams per beer. Michelob has a low carb beer that cuts that in half, and Miller light is considerably lower (also tastes like horse-pee IMHO).