Why You Still Feel Dehydrated After Drinking Lots of Water

We all know the importance of drinking water and have the harrowing, cautionary tales of run-ins with dehydration (usually linked to particularly noteworthy hangovers) to prove it. Those lessons were learned the hard way and set the foundation for the long-term relationship with our emotional support water bottle we've since been nurturing. But while we've committed to drinking our weight in water—and accepted the many, many trips to the bathroom that result—we can't say we always feel particularly well hydrated. Regardless of how much water we dutifully consume, the thirst persists.

Thankfully, this is a fairly common occurrence and can happen for a few reasons ranging from your body’s needs to internal imbalances. To better understand the situation, we spoke with expert physicians and dietitians about hydration. Here’s everything you need to know. 

Why Is Hydration Important?

It’s no secret that hydration is important—we hear about this a lot. But there’s less information floating around on the why behind it all. “Good hydration is critical for the functioning of our bodies,” explains Linda Anegawa, a physician at the virtual health platform PlushCare. “Water in our bodies ensures that our blood circulates adequately, wastes are removed efficiently, body temperature is regulated through sweating, and hormones and signaling molecules needed by the nervous system are produced.”

Dana Cohen, an internal and integrative medicine physician and author of the book Quench, says staying hydrated is the single most important thing one can do to treat and prevent chronic illness. “It is the baseline of all homeostasis in the body,” she says. “It regulates body temperature, it is an energy source, and it keeps our cells, fascia, joints, skin, and brain lubricated and in motion.”

How Much Water Is Enough?

Before you’re able to address dehydration, you need to understand the basics of staying hydrated. Although everyone has slightly different needs, according to our experts, the simplest rule of thumb when determining how much water to drink each day is to divide your weight in half and drink that amount in ounces. In other words, if you weigh 140 pounds, you’ll want to drink around 70 ounces of water each day. That’s about nine glasses, or a few refills of your Hydro Flask.

But that rule isn’t set in stone—you may need more or less water depending on your diet, medications, the environment you live in, toxic exposures, activity levels, and other factors. Foods that contain a lot of water can be hydrating as well, so you may not need to drink as much to stay hydrated if you’re eating a lot of produce like cucumbers, strawberries, watermelon, celery, and other hydrating fruits and vegetables:

“If you eat the recommended five to seven servings of vegetables daily, you can probably consume more like 75 percent of the recommended water for your weight, and be well hydrated,” says Caitlin Self, a licensed dietitian/nutritionist. “So if a 150-pound person has a veggie-packed salad every day, carrots and cucumbers for a snack, and two servings of vegetables with dinner, he or she might only need 50 to 60 ounces of water daily.”

Signs of Dehydration

If you’ve ever been dehydrated, you’re no stranger to some of the common signs and symptoms—headaches, fatigue, dry skin, constipation, stiffness, brittle hair, urine thats dark in color, and muscle cramps. “If you’re not urinating frequently, that’s another sign that you’re not getting enough fluid throughout the day,” Self says.

Reasons for Persistent Dehydration

There are a few reasons you may feel dehydrated even after drinking the recommended amount of water. Here’s what our experts shared:

• You might have an electrolyte imbalance: Electrolyte imbalances are one of the most common reasons you might feel dehydrated even after drinking tons of water. “Sometimes if we drink a lot of water but we don’t take in enough fruits and vegetables, our electrolytes—sodium, potassium, magnesium, chloride, etc.—can get flushed out with the water,” Self says. “Our body triggers a thirst response, which causes us to drink more water and causes further dilution of electrolytes.” Electrolytes and fiber are needed to absorb water into our cells, Cohen says. “We like to say in our book, Quench, that an apple and a bottle of water is more hydrating than two bottles of water,” she explains. Bananas, coconut water, and lots of other foods contain important electrolytes that hydrate your body, regulate muscle and nerve function, and a whole lot more.
• You’re sweating a lot: Your body loses electrolytes and fluids as you sweat. If both of these aren’t replenished, you may start to feel pretty bad. “If we sweat out a lot of fluid and then drink a lot of plain or bulk water without those electrolytes we just sweat out, then it can actually flush out even more electrolytes and be dangerous,” Cohen says. Rather than guzzling down water when doing an intense workout, especially on a hot day, sports drinks may be a better option to help you stay hydrated and maintain a proper electrolyte balance. But be mindful of how much you consume—many sports drinks are loaded with sugar. 
• You’re hungry: There are some overlapping signs between hunger and dehydration, such as irritability. Self explains that this is more common for individuals with blood sugar dysregulation.
• It takes time for your body to hydrate: If you become dehydrated, it can take a while for your body to be properly hydrated, even if you’re drinking a lot of water. Anegawa explains how this works: “After drinking water, fluids initially enter our circulatory system. From there, fluid is partitioned out into other body tissues, which will temporarily drop the fluid content in our circulation. So even if you drink a large quantity of water, more may be needed to ensure proper rehydration.”
• You’re taking a medication that’s a diuretic: Some medications are diuretics, meaning they flush the body of salt and water. If you’re taking a medication that’s a diuretic, you could become dehydrated as important fluids and electrolytes are pushed out of your body.

How to Increase Hydration

In addition to the specific tips shared above, these general guidelines can help you maintain a well hydrated system and finally quench the thirst.

• Drink When You're Thirsty: This may seem like an obvious statement, but it can help counteract any deficits we may not be accounting for in our daily water calculation. Workouts, dry climates, high temperatures, and fighting an illness can all increase the amount of water you need to feel fully hydrated.
• Prioritize Water: Water may not be the most enticing beverage around, but it is the most dependable. While tastier drinks like soda, juice, coffee, tea, or even flavored water sound like great substitutes, they often contain sugar, caffeine, or other components that can actually dehydrate the body.
• Consider Timing: Your body can only absorb so much water at once, so chugging the majority of your daily intake in one sitting won't get you there any faster. It will just overload the system and be really uncomfortable.
• Eat Your Water: Liquids aren't the only source of water available. Fruits and vegetables can also be high in water content as well as the necessary minerals and electrolytes necessary for optimal absorption and hydration.

Is It Possible to Drink Too Much Water?

While water consumption is a critical part of keeping our bodies healthy, it is possible to over hydrate. “Drinking too much water can actually lead to a condition called water intoxication, in which excess water dilutes out important blood electrolytes such as sodium, potassium, magnesium and calcium,” Anegawa says. 

This can lead to complications like muscle cramping, weakness, heart arrhythmias and fatal brain swelling, but the more severe complications are rare and would require drinking in excess of a gallon or two of water each day, according to Anegawa.

The Takeaway

Water is the age-old antidote to dehydration, but it may not be the only factor to consider. As it turns out, proper hydration is about much more than just chugging a ton of water throughout the day. Mindfully balancing that water consumption with electrolyte-rich foods and responding to unique changes in your body's hydration needs will ensure you're actually receiving every long, refreshing glass.