Beer spikes your blood sugar more than a candy bar.

Maltose, the sugar left over in beer after fermentation, absorbs faster than table sugar. Your body dumps insulin, crashes your blood sugar, and you wake up with a headache.

Grapes contain simple sugars that yeast eats during fermentation. Dry red wine ends up with 1/10th the sugar of beer, and what's left doesn't hit you as hard.

That's why you feel clean after drinking it.