Experts Explain Why You’re Still Dehydrated After Drinking Water All Day

You often hear the old “eight glasses of water a day” adage as a way to stay hydrated. But unfortunately, hydration isn’t as simple as refilling your Nalgene and chugging plenty of H2O. In fact, it’s possible to still feel thirsty and dehydrated, even if you’re someone who prides themselves on their water-drinking game.

If you drink a lot of water and still feel dehydrated, something else may be to blame. “Typically, dehydration means a loss of fluid in the body,” says Kelly Unger, a certified personal trainer, nutritionist, and co-founder of Epic Fitness. While it’s typically caused by not drinking enough, other factors like certain illnesses or excessive sweating can throw your body out of whack.

Since dehydration is never a good feeling, it’ll be important to get to the bottom of your thirst and pinpoint the exact cause so you can get yourself back on track. Some signs of dehydration to watch for include dry mouth, bad breath, extreme thirst, less frequent urination, and dark pee. And if you’re really dehydrated, you might feel dizzy, tired, or stop sweating completely.

It might be confusing if you experience these signs even after drinking lots of water, but drinking water isn’t all that it takes to stay hydrated. Here are some reasons you might feel dehydrated despite seemingly adequate water intake, according to experts.

You’re Missing Electrolytes

“You may be drinking enough water but still have feelings of dehydration if you have an electrolyte imbalance,” says Dr. Natasha Trentacosta M.D., a sports medicine specialist and orthopedic surgeon at Cedars-Sinai Kerlan-Jobe Institute.

Electrolytes like sodium, chloride, magnesium, and potassium are necessary to deliver fluids to your cells, she says. If you lose them by excessively sweating at the gym, for example, it really can throw things off. She recommends focusing on drinks with a lot of electrolytes, like coconut water, and eating fruits and vegetables with a lot of fiber to combat these losses.

You Drank Too Much Water

Believe it or not, drinking too much water can also make you feel off due to the way it impacts electrolytes. “Consuming water, especially in excess, can flush out electrolytes and fiber,” Trentacosta explains. The National Academies of Science, Engineering and Medicine recommends drinking about 91 ounces, or 2.7 liters, per day.

You Drink All Your Water At Once

Are you the kind of person who drinks three glasses of lemon water first thing in the morning? If so, it’s important to make sure you drink water throughout the day, instead of glugging it all in one sitting. “Your body will absorb more water over the course of the day, rather than at one shot,” says Scott Michael Schreiber, DC, a board-certified rehabilitation specialist.

It Could Be A Sign Of Diabetes

If no amount of water seems to quench your thirst and you’re urinating excessively, it’s time to check in with your doctor. “This may be the first sign of diabetes,” Trentacosta says. Because the body is trying to get rid of sugar, people with diabetes may pee frequently, which can dehydrate them. If you’re always thirsty and pee a lot, it may be worth it to get tested for diabetes.

You Were Recently Sick

An illness can cause you to feel dehydrated, says registered dietician Kristin Gillespie, MS, RD, LD, whether you were vomiting, had diarrhea, were excessively sweating, or dealt with all of the above. “Obviously increasing your fluid intake is necessary to combat these fluid losses, but often that’s easier said than done, especially during illness,” she tells Bustle. “Keeping fluids on hand and sipping on them throughout the day as opposed to trying to drink large amounts at a time may be easier tolerated.”

This is the moment when you might lean into drinks like Pedialyte or Gatorade. “Not only do these contain electrolytes, which are also lost through the sweat and gastrointestinal losses, but they are also often absorbed more readily within the body,” Gillespie says.

You Take Certain Medications

Some kinds of medications can make you more prone to dehydration. “Some medications purposely flush water and electrolytes out of the body,” Trentacosta says, pointing to diuretics, laxatives, antacids, and even blood pressure medications as examples. Since some of these may list dehydration as a side effect, check in with your doctor to see what they recommend in terms of staying hydrated.

You Live In A Hot Climate

Even if you’re drinking eight glasses a day or more, that may still not be enough for you, depending on your size and level of physical activity. “You may not actually be getting as much water as you think,” Dr. Trentacosta says. “The general recommendation is to drink about eight glasses of water a day, but this should be tailored to individual’s weight and activity levels.”

You’re Drinking Dehydrating Fluids

Consider what you drink besides water. According to Gillespie, if you feel thirsty, you should try to increase your intake of hydrating fluids, like water, tea, and sports drinks, and cut back on beverages that contain alcohol, as it may have a slight diuretic effect.

The same is true if you’re a big fan of coffee and soda. “Many individuals use these products as one of their fluids,” says Jaramillo. “In reality, we should be matching each of these consumed beverages with an additional glass of water.” If you aren’t a fan of plain water, Gillespie recommends infusing yours with fruit or adding a flavor drop to enhance the taste.

You’re Wearing Too Many Layers

Another quick way to feel dehydrated? Making yourself sweat by wearing too many layers. “Sweating is your body’s way of trying to lower your body temperature,” Unger says. Make sure you aren’t making your body work harder by sitting around in three sweaters and a stack of blankets. It won’t necessarily cause you to become dehydrated, but it’s something to consider if you can’t figure out why you’re always chugging water.

You Have A Hormonal Imbalance

It’s also possible you have a hormonal imbalance, says board-certified clinical nutritionist and functional medicine practitioner Filipa Bellette, Ph.D., especially if you have to pee almost immediately after having a glass of water.

Bellette points to a stress-related hormone imbalance in particular, noting that it can cause the body to be mineral deficient. “If a person is mineral deficient, they are unable to absorb water into their cells, meaning they start urinating almost all the water they are drinking, leaving their body dehydrated despite the amount of water a person is drinking,” she tells Bustle.

This and other health issues are something you can get tested for at your doctor’s office. If you can’t figure out why you feel dehydrated and thirsty all the time, it’s good to start ruling things out.

You Always Wait Until You’re Thirsty

“When you are thirsty, you are already heading down the road to dehydration,” Schreiber says, which is why you need to be drinking water all day long — not just when you are thirsty. “Your body will absorb more water over the course of the day rather than at one shot,” he explains.

Since it’s tough to remember to drink water, especially if you’re busy or have an active job, Trentacosta suggests keeping track of the amount of water you drink throughout the day. Think about getting a water bottle that marks fluid amounts or using a water tracking app so that you know for sure you’ve had enough.

If you’re experiencing signs of chronic dehydration despite drinking lots of water, talk to your doctor about what might be going on and how to stay hydrated.

Studies referenced:

Belasco, R. (2020). The Effect of Hydration on Urine Color Objectively Evaluated in CIE L*a*b* Color Space. Front. Nutr., 26 October 2020 |

Freund, B. (1996). Nutritional Needs In Cold And In High-Altitude Environments: Applications for Military Personnel in Field Operations. Institute of Medicine (US) Committee on Military Nutrition Research; Marriott BM, Carlson SJ, editors. National Academies Press (US); 1996.

Giersch, G. (2020). Fluid Balance and Hydration Considerations for Women: Review and Future Directions. Sports Med.

Maughan, R.J. (1991). Fluid and electrolyte loss and replacement in exercise. J Sports Sci.

Popkin, B. M., D’Anci, K. E., & Rosenberg, I. H. (2010). Water, hydration, and health. Nutrition reviews, 68(8), 439–458.


Scott Michael Schreiber, DC, board-certified rehabilitation specialist

Dr. Natasha Trentacosta MD, sports medicine specialist and orthopedic surgeon at Cedars-Sinai Kerlan-Jobe Institute

Shena Jaramillo MS, RD, registered dietician

Filipa Bellette, Ph.D., board-certified clinical nutritionist and functional medicine practitioner

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