[chris (OP)]

Recently I was in Perth for the Science on the Swan conference where I also delivered a public lecture on healthy living, which included a Q&A session. There were some follow-up questions, which I am answering here; this is one of them:

Brittany says:

How long does it take people to completely sober up?
Is there anyway to sober up faster?
How does one get skinny while eating a lot?

[chris (OP)]

How long does it take people to completely sober up?

You become "drunk" when ethanol (alcohol) activates pathways in the brain that use the nerve transmitter GABA, which is inhibitory. This damps down brain activity, causing the sedating effect with which drinkers are familiar.

To reverse this effect the alcohol has to be removed from the body. A fraction is lost in urine, sweat and via exhaled breath, but the bulk is metabolised, chiefly in the liver.

Most of the heavy lifting is done by the enzyme alcohol dehydrogenase, ADH, in liver cells. This oxidises ethanol to the molecule acetaldehyde. Acetaldehyde is then converted to acetate, otherwise known as vinegar, by a second enzyme called mitochondrial aldehyde dehydrogenase (ALDH).

Another pathway for ethanol metabolism is known as the microsomal ethanol oxidizing system (MEOS). This uses an enzyme called cytochrome P450 CYP2E1. This system is upregulated in people who consume a lot of alcohol, contributing to the tolerance they display.

There is a third, non-oxidative pathway for alcohol breakdown which uses an enzyme called fatty acid ethyl ester (FAEE) synthase. This turns alcohol into fatty acid ethyl esters, and takes place in the liver but also in the pancreas. The toxicity of the products partly explains why heavy drinking is linked to bouts of pancreatitis.

The combined contributions of these pathways slowly remove alcohol from the blood at the rate of about 0.016% per hour (Wilkinson PK, Sedman AJ, Sakmar E, Kay DR, Wagner JG. Pharmacokinetics of ethanol after oral administration in the fasting state. Journal of pharmacokinetics and biopharmaceutics. 1977;5(3):207-224). Practically speaking, this means that you metabolise about 1 unit of alcohol every hour. One unit is roughly equivalent to the alcohol in half a pint of beer, a glass of wine or a measure of spirits. That rate of detoxification is also broadly similar for males and females, large and small.

As the concentrations fall in the blood, alcohol dissolved in brain tissue moves back out into the blood, permitting brain function to return to normal and slowly reducing the sensation of drunkeness. 

Is there anyway to sober up faster?

In a word, no! You need to wait for your metabolism to break down the alcohol for you. This means that you could well be over the safe limit to drive the morning after a heavy night...

How does one get skinny while eating a lot?

The rules of physics are not being re-written in the intestines of the overweight. Energy in must equal energy out (i.e. calories burned), or you will gain weight.

The only exception to this is if you prevent your intestines from absorbing the calories that you take in. There are some fairly unpleasant medicines that work in a range of ways, including inhibiting the digestion process, to prevent the full calorie burden of the diet from being unlocked and absorbed. The downside is that what goes in must come out, so visits to the lavatory can become more regular and much less pleasant...

[evan_au]

Is there anyway to sober up faster?

Drink in moderation?

[RD]

Brittany says:
... Is there anyway to sober up faster? ...

Liver dialysis ?, (very expensive).

[Bored chemist]

Theoretically
https://en.wikipedia.org/wiki/Exchange_transfusion
but it would take longer to set up the process than to simply wait + sober up.