While caffeine is a mild diuretic and can cause your body to lose some water, in the grand scheme of things, the fluids lost are negligible, says board-certified sports dietitian Tara Gidus, M.S., R.D., C.S.S.D. And, in the end, isn’t coffee largely water (or, if you’re into fancier drinks) milk? Meaning coffee addicts are more than caffeinated. They’re also hydrated.
Does Coffee Dehydrate You?
The reasoning holds up. In one recent study, when University of Birmingham researchers examined the hydration levels of 50 men who regularly downed three to six cups of coffee each day, they determined that coffee hydrates about the same as water does. Coffee is actually growing in popularity as a research-supported pre-workout drink.
“Most people are well adapted to caffeine,” explains Gidus, who says coffee and tea can contribute to most peoples’ daily fluid intake. (So, if you’ve long been shamed by people saying coffee will dehydrate you, you can relax.)
Your goal, though, shouldn’t exactly be eight glasses of water or coffee per day.
The Institute of Medicine recommends men consume 120 ounces of fluid, and women, 90 ounces per day. While that’s a lot more than the 64 we always assumed we needed (aka eight glasses), if your diet is rich in water-logged foods like fruits and veggies, you can count on eating about 20 percent of your fluid needs each day, Gidus says.
The rest–or about half your body weight in fluid ounces–should come straight from sucking down drinks. And, yes, coffee counts. So for example, a 180-pound person should aim to drink roughly 90 ounces or 11 cups per day.
In the end, though, your hydration levels depend on tons of factors ranging from your exercise habits to your city’s humidity levels. The best way to check your hydration levels is to look at your pee: If it’s pale yellow or approaching clear, you’re good to go. If it’s dark or stinky (and no, the asparagus smell doesn’t count), you should probably start pushing fluids.
RELATED: Can You Drink Alcohol and Still Lose Weight?