I drunk about 4 cups of coffee a day at the moment without milk or sugar. I have a few friends who keep insisting it's going to damage my kidneys. Anyone here have any insights on the medical sude effects of too much coffee?

http://med.stanford.edu/news/all-news/2017/01/caffeine-may-counter-age-related-inflammation-study-finds.html
http://www.nejm.org/doi/full/10.1056/NEJMoa1112010

but honestly i dont even think these mean much. id just go off of how you feel

ive been in investment banking for the past 2 years, usually drink 4-6 cups per day depending on how tough the hours are
used to feel pretty shitty until i also started to drink a gallon of water per day

What do you think logically

Good if you need to cleanse that colon.

if we look @ all the ways to cleanse your colon, is caffeine really the best way...

coffee isn't inherently bad for your kidneys lol.

what your friend may have meant was that coffee is a diuretic and dehydration obviously doesn't make the kidneys too happy.

assuming by 4 cups you mean 32oz a day, that's a pretty normal amount for coffee-drinkers, maybe even on the low end (some people get a 24oz and call it a cup though)

anyways, here's a nice little potion for optimal hydration: 1liter water, 6tsp sugar, 1/2tsp salt. tastes awful.

Nonsense. It's hardly even a diuretic too, just mildly increases gfr via dilating afferent arterioles to the nephrons through antagonizing adenosine receptors. Actual diuretics tend to actually act within the nephron, where the resorption takes place, on the transporters doing the actions, like the NKCC or NCC transporters. That said, coffee = sublime nectar. Myriad benefits, modicum of downsides. Do it.

I don't see a problem.

Four cups or like four XL coffees from a store?

Four cups is definitely fine. The four XL I would think not.