10 Crazy Things Booze Does To Your Body

3. Breaking The Seal

But if alcohol isn't a diuretic, why do I need to pee so much when I drink?

So the idea that alcohol makes you pee is due to its supposed ability to suppress the production of vasopressin, a hormone that regulates your hydrations levels. 

But we've already discovered that alcohol does not significantly dehydrate you, so what else is going on?

There are a couple of reasons why you need to pee so much when you're drinking, and one of these is that fact that you're actually over-hydrated. During drinking sessions, you are taking on massive amounts of liquid, of which only a small amount is alcohol.

If you think about it, imagine how much you would need to pee if you sat for four hours and took a gulp of water every 30 seconds or so. Even if you only have a pint per hour, and many people drink much more, that is a massive amount of liquid to be taking on over a short period of time, alcohol or not.

So what about "breaking the seal"? Why is it that once you start peeing you just can't seem to stop? Well, apart from the fact that you are taking on more and more liquid faster than your body can process it, it also comes down to the fact that alcohol is a muscle relaxant.

This means that once you have relaxed you sphincter muscles to pee, you can't quite get them tensed back up completely and you will feel the pressure to pee much more quickly after that. 

However, it's not a great idea to hold it in, because that muscle is going to weaken eventually anyway and you do not want a full bladder when that happens.