alcohol - dehydration - rehydration

[newtron]

Exactly why does beer dehydrate you even though it contains water?

How much water do you need to drink per beer to stay hydrated?

How about per shot of hard liquor?

[newtron]

Sorry, I accidentally put this question in the wrong category.  Oops!

[Jenny Tools]

Alcohol is a diuretic which causes the loss of fluid from the body more then is contained in the beer in the first place.

[rinkytink]

 

Basically Alcohol confuses your body. It makes it think it has more waste to flush out of your system (urine) than you actually do. Hence when you drink a lot you actually wee out more than you drink which is why you become dehydrated.

 

This is why when you are really drunk your wee is no longer yellow but clear - it's basically just water. Your body is confused and it's flushing out the waste - when there is no waste to flush !!

 

This also why a lot of people find that drinking a few pints of water before going to be after a heavy night eases a hang over. You are replacing the fluid lost when drunk.

[newtron]

Is it an actual biological response by your body or does it have to do with osmotic pressure?  For example, if you have a semipermeable membrane (a cell membrane) with pure water on one side and a solution on  the other side (in this case, alcohol would be the solute), water would move through the semipermeable membrane to dilute the solution on the other side.  The solution has a lower osmotic potential than pure water and water will move from high osmotic potential to lower osmotic potential.  This is just an example. I know cells do not contain pure water.  Thanks for the answers, but I am still looking for a more complete answer.

[Octavius]

Dehydration occurs because alcohol is a diuretic (i.e. it stimulates urination).  Alcohol also stimulates the production of insulin which in turn reduces blood sugar levels.  Low blood sugar produces feelings of drowsiness, weakness, trembling, faintness and hunger.

Diuretics increase the amount of urine produced by encouraging the removal of salts such as potassium and sodium (salt) from the blood. As a result, an increased amount of water is drawn out of the blood and into the kidneys, where it is passed out through the urine.

Alcohol can also cause malnutrition because it uses it the body�s store of vitamins and minerals and reduces blood sugar levels. Together with dehydration, this can be responsible for the throbbing headache you may experience with a hangover. Alcohol can also cause blood vessels in the head to dilate, adding to the pain of a hangover headache.

A small amount of alcohol (less than 10 per cent) is eliminated from the body in urine, breath and sweat.  The rest is oxidised i.e. like food, it combines with oxygen in the blood to release heat, energy or calories.

As a general rule, each unit (8g) of alcohol takes at leats one hour to be eliminated from the body.

[soonny]

Alcohol can inhibit the secretion of a hormone known as ADH (Anti Diuretic Hormone). This hormone is secreted by the body (posterior pituitary) when it senses the need to retain water for example during a hot day when you sweat more than usual. If you'd already understand the detailed anatomy of a kidney, perhaps you've read about aquaporin pores located in the descending loop of Henle of an individual nephron. ADH opens these pores so that water can be reabsorbed during the filtering process to produce urine.

 

So when ADH is inhibited, urine is produced above the norm. Thus alcohol is known as a diuretic (an agent that stimulates the production of urine).