I paid a fairly embarrassing visit to see a new doctor this month—about 10 minutes into what was supposed to be a routine ear exam, I nearly fainted (and naturally, he questioned whether I was dehydrated). I proceeded to tell him I might be, and I asked him, “so how much water should I drink a day?” He said that based on my size, about six to seven glasses a day would be good, but I was a little perplexed. What happened to the eight-glasses-a-day rule we've all heard about all our lives?
“There are no good scientific studies to support the eight-by-eight rule,” says Leigh Vinocur, MD, FACEP. “The original guidelines came from a misinterpretation of a recommendation from the Food and Nutrition Board.” The Institute of Medicine has set some guidelines, suggesting that women drink 91 ounces per day (mind you, that’s more than 11 eight-ounce glasses of water). So you’re probably wondering how that is possible. Well, you need to remember that about 25% of the water intake we get is from fluid-packed fruits and veggies.
Since it’s all a little confusing, let us give you the rundown of how much water you should drink each day, depending on your lifestyle (and other important factors).
If you're a healthy adult
If you’re 19 or older, the IOM says that females should drink around nine cups of water a day and males should drink about 13. As a heads-up, children should drink significantly less, and it varies based on their age group. To note: This is straight water only. “It’s also important to remember that water intake doesn’t just come from guzzling water—it also comes from what you eat,” Kara Griffin, personal trainer, holistic nutritionist, and health coach, told Byrdie. “You naturally up your water intake by eating clean, unprocessed, whole fruits and vegetables." (For example, watermelon is about 93% water.)
If you're pregnant
If you’re expecting, it’s no surprise that your liquid intake should increase. When pregnant, women should drink a suggested 80 ounces of water daily (about 10 cups). And if you’re breastfeeding, that amount can go up to as much as 13 glasses of water a day (wow). If you have any questions, consult your doctor.
If you work out a lot
If you’re frequently exercising, you can add about 1.5 to 2.5 extra glasses of water to your daily regimen if you feel like you need it. But drinking too much water can backfire on you and cause symptoms like stomach upset, dizziness, and more. If you take it to the extreme, your sodium levels can drop too low and cause hyponatremia, which leads to dangerous swelling in the brain.
If you have a medical condition
The medications we take can also affect our levels of thirst and hydration. According to Vinocur, these drugs are especially those used to treat stomach ulcers, depression, heart disease, and diabetes insipidus. Individuals with specific conditions like kidney stones or regular urinary tract infections may also need to up their H20 intake. “They may need to over-hydrate from time to time and may benefit from excess water to flush out their kidney stones or bacteria from their bladder,” says Vinocur.
If you're sick
“Hydration is key when trying to get rid of pathogens,” says Carly Brawner, holistic nutritionist, health coach, and founder of Frolic and Flow. “They will most likely be excreted through urine, so drinking at least 80 ounces a day is ideal.” Which brings us to this note: You can simply judge your level of hydration by looking at your urine (we know, it’s not fun to talk about). But what are we looking for? “It should be fairly clear, and if it is dark yellow, that’s a sign we may need to drink more water,” Vinocur says.
Up next, how to kick-start healthy eating habits.