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Why Do You Get Dehydrated on Keto? Everything You Need to Know


A ketogenic diet comes with plenty of upsides — from weight loss to blood sugar control to epilepsy management — but one downside is the possibility of dehydration. If you’ve noticed an uptick in your thirst since starting keto, you’re not alone. Dehydration is actually a relatively common symptom for people on this diet. It can even be a promising sign that you’ve achieved ketosis — the fat-burning metabolic state you’re striving for.

That said, the symptoms of dehydration are never pleasant. When you find yourself suffering their effects, you probably want relief fast. Here’s how to manage dehydration while on keto (or, better yet, prevent it before it starts).

Why You May Get Dehydrated on Keto

Aside from the macronutrient content of the beverages you drink, a keto diet doesn’t place any parameters on your fluid intake. So you may wonder: Why does this eating plan seem to affect your hydration so much?

Dehydration on keto comes down to the far-reaching effects of ketosis. When your body shifts into this metabolic state of burning fat for fuel, the liver creates ketones. These are water-soluble compounds made of fatty acids. Instead of using carbohydrates for fuel, your body will use ketones for energy, releasing them into your bloodstream.

The problem is, ketones have a diuretic effect, making you urinate more often — thus losing water. (This is why you’ll sometimes hear your initial weight loss on keto referred to as “water weight.”)

Meanwhile, as your body switches away from using carbs as fuel, the liver also releases its glycogen stores. This form of glucose is stored with lots of water. Again, this exits the body through urine, leading to dehydration.

A low-carb diet also leads the body to produce less insulin. Less insulin in the bloodstream signals your kidneys to excrete sodium at a higher rate.[*]

And when it comes to sodium, a keto diet often means eating lower amounts of salt than the standard American diet you may have consumed in the past. Since sodium helps the body retain water, getting less of it can cause your body to not hang on to as much fluid.

Although these are all good signs that your keto diet is working, they can lead to the dreaded keto flu — a constellation of symptoms that include dehydration, fatigue, headaches, and a general feeling of “ick.” For many people, the keto flu will resolve within a few days or up to a week. In the meantime, though, you can minimize your symptoms by focusing on rehydrating with fluids and electrolytes.

Signs of Dehydration on Keto

When your body’s fluid stores get too low, it’s a recipe for some uncomfortable effects. Some signs of dehydration you may notice as your body adjusts to a keto diet include:

  • Excessive thirst
  • Dry mouth
  • Muscle cramps or spasms
  • Dry eyes
  • Headaches
  • Fatigue
  • Feeling confused or having brain fog
  • Constipation

While these symptoms may be more unpleasant than dangerous, dehydration can become serious if left untreated. When you begin to notice signs your fluid stores are getting low, take action sooner rather than later.

Potential Effects of Dehydration

Getting dehydrated doesn’t just mean feeling thirsty. When your body is low on fluids for too long, it can lead to serious health problems. Without proper hydration to flush out waste, acids and waste products can build up within the kidneys and urinary tract, causing kidney stones, urinary tract infections, and even kidney damage.[*]

Some research has shown that low fluid stores could diminish cognitive performance, short-term memory, and attention.[*] Constipation and headaches are other common complaints. Chronic dehydration could even cause an increase in blood pressure.[*]

Non-Keto Causes of Dehydration

While it’s certainly possible that a keto diet is the cause of your dehydration, it’s important to remember that there are other potential reasons your body may be depleted of its water stores.

Non-keto causes of dehydration can include[*]:

  • Age. Older adults have a less acute sense of thirst than younger people, putting them at higher risk of dehydration.
  • Hot temperatures. There’s always the chance that the weather is influencing your hydration status. When it’s blazing hot outside, your body naturally releases more water through sweat, so it’s harder to stay on top of hydration.
  • Fever or illness. A fever or a recent bout of diarrhea or vomiting can easily diminish your body’s fluids.
  • Medications. Numerous medications come with dehydrating side effects. Do your research to determine whether a medication you’re taking could be causing your body to lose water.

Still feeling confused about the cause of your dehydration? A visit to your doctor can help you get the answers you need.

The Connection Between Electrolytes and Hydration

Brightly colored beverages have reigned in the sports beverage category for decades with the promise of replacing lost electrolytes. But have you ever wondered exactly what electrolytes are?

Simply put, electrolytes are minerals that have an electric charge. They help the body retain water, keep muscles contracting properly, balance pH levels, and maintain nervous system function. Electrolytes include sodium, potassium, calcium, chloride magnesium, phosphate, and bicarbonate.

When you sweat or urinate a lot — as may happen on keto — these critical substances can get too low in your bloodstream. If you’re low on electrolytes, your body will have a harder time staying hydrated. This is why drinking fluids alone may not do the trick to rehydrate you. Instead of just gulping your way through a jumbo-sized water bottle, it’s best to couple your fluid intake with multiple sources of electrolytes.

Electrolyte Imbalance

As with most things in the body, keeping the right ratio of electrolytes is a delicate balance – which can sometimes become disturbed. Electrolyte imbalances occur when your body stores up too many (or too few) of these electrically charged substances. Altering your hydration status may make you more likely to experience this.

The names for these imbalances have Latin roots. If you’ve ever learned a little Latin, you may remember that the prefix “hyper-” refers to too much of something, while “hypo” means too little. Hypercalcemia, for example, is an excess of calcium, while hyponatremia refers to too little sodium.

Each excess or shortage of a specific electrolyte will lead to unique symptoms. Certain health conditions can predispose you to experiencing electrolyte imbalances when you get dehydrated. Talk to your doctor if you’re concerned that keto-related dehydration might be creating an imbalance.

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How Much Water Do You Need on Keto?

Just like there’s no hard and fast rule about exactly how many grams of carbs you should get on a keto diet, there’s no perfect target for water on this diet, either. While we’ve all probably been indoctrinated with the rule that good health comes from drinking eight eight-ounce glasses of water per day, this advice isn’t necessarily supported by science (and shouldn’t necessarily be your goal while on keto).

Some experts advise drinking up to 2.5 liters of water per day when first starting out on keto to prevent dehydration. But rather than obsessing over exactly how much water to drink each day, it’s usually a better strategy to simply drink when you’re thirsty.

If symptoms of dehydration (like those listed above) crop up, you can escalate your efforts to drink more. However, overdoing it by chugging liter after liter of water will likely only make you uncomfortable. There’s no need to go around with a bloated, sloshy belly full of fluid.

Preventing and Combating Dehydration on Keto

Don’t let dehydration get you down! When your fluid stores are running low, try these eight rehydration strategies.

Get More Electrolytes from Foods and Beverages

You’ve seen the various sports drinks on grocery store shelves (usually with “-ade” in their names) making claims about their electrolyte-restoring powers. But believe it or not, these beverages don’t own the market on electrolytes — and when you’re on keto, their high amounts of sugar and carbs aren’t a good idea anyway.

To maintain hydration, you can add electrolytes to your diet from numerous other sources. For a natural sports beverage alternative, try coconut water. It contains plenty of sodium and potassium, along with smaller amounts of calcium and magnesium. A DIY veggie juice or smoothie with ingredients like leafy greens and berries will also help replenish magnesium and potassium stores. (Use a coconut water base for a one-two electrolyte punch.)

Meanwhile, it pays to think beyond the drink! Tons of common, healthy foods are excellent sources of electrolytes. For a hefty dose of sodium, sip a cup of broth or low-carb soup. Or, to focus on potassium, reach for bananas, cooked broccoli, seafood, or tomatoes. Magnesium-rich foods include pumpkin seeds, cooked spinach, dry-roasted cashews and almonds, and (yum!) dark chocolate. The more you choose high-electrolyte foods, the easier it will be for your body to retain its precious fluids.

Take an Electrolyte Supplement

If you’d like to know exactly how much of each mineral you’re putting in your body, you may prefer an electrolyte supplement. You can purchase electrolyte supplements specifically tailored for keto — like Perfect Keto Daily Electrolytes.

This convenient powder comes in several fruity flavors, each of which provides 60% of your daily magnesium needs, plus sizable doses of chloride, sodium, and potassium. Even better: it contains zero calories, zero carbs, and zero sugars.

Want to shop around a bit more? Don’t miss our tips for choosing the best keto electrolytes.

Set a Water Goal

It’s always smart to drink when you’re thirsty, but with a busy lifestyle, it’s all too easy to get distracted and forget to drink. If you notice you tend to go through whole days with only a sip of water here or there, consider setting a daily water intake goal. Perhaps you’d like to work toward six, eight, or 10 cups of water per day, depending on how you know your body responds to various levels of hydration.

Eat Water-Rich Whole Foods

For restoring hydration, water-rich whole foods are the best of both worlds. Not only do they provide fluids with their natural water content, many of them are high in the minerals that help your body retain fluid. When a lack of fluids has you feeling sluggish (or just plain thirsty), work low-carb fresh produce choices like celery sticks, tomatoes, cucumber slices, berries, and lemons into your meals and snacks.

Try a Fluid Tracking App

You probably track all sorts of things on apps these days, from your workouts to your finances. Why not snag another icon on your phone to monitor your hydration? Fluid-tracking apps like WaterMinder or Aqualert allow you to set daily goals and log your progress. And if you need virtual accountability, some will even prompt you to drink at certain times of day.

Invest in an Appealing Water Bottle

For some people, the problem of getting enough water comes down to aesthetics. Run-of-the-mill plastic water bottles or a clear, basic glass aren’t the most inspiring receptacles for your daily H2O (and an uncovered glass definitely doesn’t travel well).

Make your hydration efforts more intriguing by investing in a quality water bottle that’s pleasing to the eye. When you enjoy the look and feel of your chosen container, you’ll be more likely to want to grab it before heading out for the day.

Try Infused Water for Extra Flavor

Understandably, not everyone gets excited about drinking plain water around the clock, either. The reality is, water’s ho-hum flavor can feel pretty boring day after day. On keto, though, you may feel like your hydration options are limited, since many flavored drinks contain high-carb sweeteners.

Fortunately, there’s a way to jazz up plain water without overdoing it on carbs. Enter the delicious world of infused water! Letting cold purified water steep with refreshing fruits (like citrus, pineapple, or mango), herbs (like fresh basil or rosemary), and even vegetables (like cucumber slices) creates complex flavor without knocking you out of ketosis. Or, if you prefer an extra level of convenience, sample the panoply of unsweetened sparkling waters the market has to offer.

Amp up Other Fluids

Infused and sparkling waters aren’t the only alternatives to plain H2O. Other keto-friendly beverages can round out your fluid intake as well. When you’re feeling “meh” about glass after glass of water, try a cup of hot or iced tea or coffee. Of course, you’ll want to steer clear of added sweeteners, but you can feel free to add richness with high-fat dairy products like half and half, butter, or heavy cream.

Another hot beverage you might enjoy: a warming cup of broth. Chicken, vegetable, beef, and bone broths all contain high amounts of sodium, which can help your body hang onto its fluid stores.

Low-carb non-dairy milks also have a place on a keto diet. Unsweetened almond milk, coconut milk, flax milk, and cashew milk are just a few of the good low-carb choices available. To make hydration more interesting, pour any of these on a keto-friendly cereal, blend as the base of a high-fat smoothie, or simply sip them solo.


It’s good to know that losing fluid can be a positive sign that your high-fat, low-carb efforts are paying off with ketosis. But a keto diet doesn’t have to leave you in a desert of dehydration — and it’s important not to let fluid losses lead to dangerous consequences.

If you’re feeling like your fluid stores are getting low, remember to drink to your level of thirst and load up on electrolyte-rich foods, beverages, and even supplements.

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