When going out for some beers, after a while, I seem to pee more than the amount of beer I drink. Is that true, and why is that?
Alcohol is a diuretic. According to this article, 1 gram of alcohol will increase urine excretion by 10ml. Combine that with this CDC article stating that a standard 12 ounce (354ml) beer has 14 grams of alcohol, your can expect to pee 494ml, or 16.75 ounces per 12 ounce bottle.
The graphic would be more accurate with you drinking three beers but peeing four.
Because beer is 95% water! Yes alcohol is a diuretic but if delivered with all this water, it is actually hydrating. If you would drink these huge glasses full of water you would urinate fearsomely as well.
So the best news ever is: beer is hydrating. There is scientific evidence for it here from 4:14 onwards. All before that is about the benefits of drinking water, yeah yeah.