Somehow the notion that you should drink eight 8-ounce glasses of water each day became gospel. But according to Dana Cohen, M.D., integrative medicine physician and co-author of Quench, “Eight glasses of water a day—it comes from nowhere,” she once said on the mindbodygreen podcast. Because let’s be honest: How can two people with completely different body types, environments, and lifestyles require the same amount of water? “It doesn’t make any sense,” she adds.
So, how much water should you actually be drinking? Well, it’s impossible to give everyone the exact same rule of thumb, as diet, environment, and activity levels can affect how much water you need (example: Keto folks or those who simply eat more meat may need to drink more water to match the dehydrating diet). But for some general guidance, Cohen recommends drinking half of your weight in ounces. So, for instance, someone who weighs 150 pounds would want to drink around 75 ounces of water, which is about 9 cups.
However, at the end of the day, it’s important to listen to what your body is trying to tell you. “The only way to know is to live in your body and know what it feels like,” Cohen adds.