Does Coffee Dehydrate You?

The last two blogs (“How to Make Hydration A Habit” and “Are You Properly Hydrated“) discussing hydration have led to a lot of great questions from clients. One of the most asked questions was regarding caffeinated coffee. “Does coffee dehydrate you?” was a question asked by a lot of terrified clients afraid to hear the answer.

Here are the facts up front for those of you who are article scanners:

1. Coffee is amazing (might be more of my opinion than fact)
2. Coffee is unlikely to dehydrate you. In fact, current research suggests it can actually help hydrate you – read further for more on this
3. It is a myth that you have to drink the same amount of water as you do coffee to break even on hydration
4. Water is the best fluid to hydrate our cells – better than coffee, juices and sodas

For those of you who don’t just scan the articles and are willing to read a few more minutes today lets learn a little more! I’ll promise to add a fun (gross?) fact at the end.

We know caffeine (I spelled it correct this time – thank you to all who noticed the error in the other blog – I was just seeing if you guys were paying attention) is a magical substance but we have also heard it is a diuretic (also a hard word to spell).

So what is a diuretic?

A diuretic is a substance that will cause your body to make more urine than usual. Caffeine in coffee can cause your kidneys to release more water through urine. Therefore, because you are urinating more frequently, your hydration status can potentially be affected.

However, even though coffee can make you urinate more, it is unlikely to dehydrate you because you don’t lose as much fluid as you originally drank. When you think about it, coffee is mostly water and why this statement proves true. The only catch to this is that it applies to moderate amounts of coffee. It seems that drinking 5 cups of coffee or more in a sitting could have a slight dehydrating effect because of the very large amounts of caffeine being consumed at once (please remember one cup is 8 ounces and not the giant thermos you drink out of on your way to work).

Personally, I have 2 cups of coffee per day. One at 7am and one at 2pm before my afternoon appointments. So according to the most recent research, my coffee intake should count towards my hydration in a positive way. I used to not drink coffee at all until my co-worker Bryan would continually buy it for me to get me hooked, presumably to make himself feel better about all of the coffee he was drinking. I do owe him though because I was clearly missing out!

If you’ve made it this far, I’ll make good on my promise with a fun fact. I was never into coffee because it did not exist in our house growing up. My parents drank Pepsi in the morning instead. My mom has a diet Pepsi every morning like a crazy person to get her caffeine fix (love you mom).

The last thing I should note is that nutrition research can change as we learn more and it is tough to create detailed rules of thumb for everybody to follow because we are all very different. But for now, us (moderate) coffee drinkers can rest easy and keep sipping!