your liver is the organ designed to process all these foreign chemicals such as alcohol and synthetic drugs, alongside a huge number of normal products of your metabolism. one of the many reasons why the liver is a great organ, is that it's dynamic - it can respond to changes in the composition of your blood and the needs of your body. so if the liver realises that there's a whole lot of one particular chemical in it's "in tray" it can step up its game a bit, and focus on this chemical.as a youth your body would have been exposed to only minute quantities of alcohol, so the enzymatic pathways for the degradation of ethanol (principally involving alcohol dehydrogenase enzymes as the rate-limiting step) would not be well established. as you then encounter this delicious molecule more and more, the liver holds a stock of the right enzymes in readiness, and you do not become so quickly inebriated.one other result of this is that if you do not drink alcohol for a long period of time (weeks to months) and then head down to the pub, you will find yourself getting drunk a lot more quickly, because the liver has decided it's not worth having a load of alcohol dehydrogenase sitting round doing nothing. another effect is that of tolerising - if the demand on the liver to process ethanol or other drugs is so great that it massively increases it's ability to deal with the load, you will find that taking small amounts of a certain substance will have no effect - so rapid is their metabolism by the liver. this can lead to long-term drug users being able to handle (or even requiring for a noticeable effect) doses that may kill a naive user.hope that answered the question. if you would like a more scientific answer i'd be happy to give one!

Beer's weaker these days!

I'd love to hear a bit more of the scientific side of the explanation.

ok, anyone feel free to correct me if i'm wrong because i'm a student doing this from memory on what we learned last year...only about 5% of alcohol consumed is eliminated as alcohol - either straight into urine via kidneys, or excreted on a persons breath, or through their sweat (some of the less pleasant effects of drinking unfortunately). it has a high affinity for water, so needs to be excreted in a lot of urine. as such it's a diuretic (makes you pee) and perversely the body needs salt to help it conserve water - which is why salty bar snacks like crisps and peanuts are so popular.all the rest of the alcohol is removed by the liver. to be metabolised the ethanol must enter your hepatocyte (liver cell) and come into contact with the enzymes you have for breaking it down. The enzyme responsible is called alcohol dehydrogenase - a cytochrome p450 enzyme, part of a large family of enzymes catalysing simple Phase I liver reactions such as oxidation, reduction and hydrolysis. This is the first and most crucial step in alcohol metabolism because it "inactivates" the alcohol. The reaction produces acetaldehyde - another simple molecule which can then be broken down into acetic acid, carbon dioxide and water. These are then pretty simple to get rid of - CO2 is breathed out, water can do whatever it wants really it's no biggie, and acetic acid can enter the citric acid cycle in your mitochondria and be used for energy. the important bit, however, is the first step.cytochrome p450 enzymes are present in the cytoplasm of hepatocytes, and catalyse this important reduction reaction. the body is pretty clever, so they are 'upregulated' or activated by the drug which they actually metabolise. this might be by increasing the rate at which this enzyme is produced from your DNA, or by decreasing the rate at which other enzymes break it down (as part of the normal protein turn-over in your body). thus - your hepatocyte suddenly comes across a lot of alcohol, within minutes to hours it will have lots of enzyme ready to chew it up. this has several implications:- a person naive to alcohol will have very few cytochrome p450s for alcohol (though they will still have some, as alcohol isn't the only thing broken down by alcohol dehydrogenase) so it will take the a little while to get used to the effects of alcohol.- if you drink alcohol frequently, small quantities of alcohol will have no effect because the poor ethanol molecules will be assaulted by an army of well-equipped hepatocytes.- if you drink heavily, the cytochrome p450 enzymes will not be able to cope with the sheer volume of alcohol - allowing toxic ethanol to build up inside your hepatocytes and cause cirrhosis.- if your cytochrome p450 enzymes are busy doing something else when alcohol arrives, they will be torn between the two jobs and alcohol metabolism will be greatly reduced. paracetamol is metabolised along the same pathways as alcohol, so taking the two together is not a good idea. again alcohol may build up and cause liver damage. that's why a students medicine cabinet should contain ibuprofen instead!- some drugs work by inhibiting the p450 enzymes, so again these should never be combined with alcoholhope that helped. if there's any more technical questions then i'll try, but i may have burned myself out.i'm off for a beer.

I'm gonna state what might be the obvious.... but how much weight have you gained between then and now? I think hangovers are also directly related to the amount of water in your body before and during the drinking times, as well as the quality of alcohol you are drinking. But I think I will just agree with Calum ultimately beer is getting weaker by the glassfull.