Alcohol metabolism

Ethanol, the alcohol in drinks, is handled almost entirely by the liver, and it happens in two steps, one after the other. Metabolizing it means the molecule gets chemically changed along the way, and that's worth keeping separate from the idea that the effects wear off the moment the work begins: those are two different things. In the first step, alcohol dehydrogenase, or ADH, takes ethanol and turns it into acetaldehyde. In the second, aldehyde dehydrogenase, or ALDH, takes that acetaldehyde and turns it into acetate.

Think of it as an assembly line with two stations: at the first, ethanol goes in and acetaldehyde comes out; at the second, acetaldehyde goes in and acetate comes out. That line doesn't run at the same speed in everyone. Some people move through it faster and some slower, and that depends both on genetics, what each person inherits, and on environment, what surrounds each person.