How Much Water Do You Need On Keto?

How Much Water Do You Need On Keto?

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How Much Water Do You Need On Keto?

Posted 4 years ago

Brian Stanton

Brian Stanton


Ari Magill, M.D.

Ari Magill, M.D.

Scientific Reviewer

Expert Approved

Dehydration is a potential cause of Keto flu. Because of this, many sources recommend aggressively swilling water on Keto to prevent the headaches, cramps, fatigue, and malaise linked to low-carb dieting. 

But while Keto does increase hydration needs, drinking more water isn’t necessarily the answer. In fact, drinking too much sodium-free water on Keto can exacerbate Keto flu. 

Why? Because over-hydrating dilutes blood sodium levels, bringing with it—yes—the dreaded symptoms of Keto flu

Don’t worry, you’ll learn a simple, practical Keto hydration strategy in a minute. First, though, let’s lay some groundwork.

What Is Hydration?

Hydration is defined as the “process of providing adequate liquid to bodily tissues”.[*

Adequate is the operative term. Not too much liquid. Not too little liquid. We’ll return to this point later. 

We provide liquid to our bodily tissues because water is essential for life. Everything from blood flow to skin health to toxin disposal depends on H2O.[*] Our bodies, you might be aware, are about 60% water weight.

The equilibrium of water in your body is called fluid balance, and the fluids you drink are just one input into that system. The other main inputs are sodium, chloride, and potassium—electrolytes that regulate fluid levels inside and outside of cells.[*

Even if you don’t get the inputs 100% correct, your body is an excellent fluid balancing machine. Along with your kidneys, a slew of hormones like insulin, aldosterone, renin, angiotensin, and antidiuretic hormone (ADH) make sure fluid levels stay just right. An example will help illustrate. 

Let’s say you’re low on fluids after a long hike. Below the threshold of conscious awareness, osmoreceptors in your brain sense a decrease in blood volume and tell a brain structure called the hypothalamus to secrete ADH. ADH then tells your kidneys to stop losing liquids through urine.[*

At the same time, the hypothalamus triggers your thirst mechanism. Then you get thirsty, drink something, and fluid balance is restored. 

This is how hydration works on Keto (or any diet), but let’s explore what’s different on Keto. 

How Keto Increases Hydration Needs

Eating a Keto diet means keeping carbohydrate intake very low. And when you keep carb intake very low, the hormone insulin—your blood sugar boss—also stays low.  

With insulin low, your liver is encouraged to start burning fat and making ketones. That’s how you enter the unique fat-burning state called ketosis

Low insulin has other effects though. Along with increasing fat-burning, low insulin also increases water, sodium, and potassium loss through urine.[*

In other words, a Keto diet raises both fluid and electrolytes needs.  

What about the water weight you lose in the early stages of Keto dieting? Doesn’t that dehydrate you?

This is a common point of confusion. Let’s clear it up. 

Early water losses on Keto are largely driven by the depletion of glycogen—or stored glucose—from muscle and liver cells. This glucose is needed for energy as the body transitions to using fat for fuel.[*] Since glycogen is mostly water weight, using it up releases a deluge of H2O. 

But here’s the thing. On Keto, you adapt to lower glycogen levels, so this water doesn’t need to be replaced. 

The release of glycogen has an over-hydrating effect—it causes too much water to be released into circulation.[*] That’s why your body pees it out. It’s smart like that. 

Preventing Dehydration on Keto

Much Keto advice is centered around preventing dehydration, defined as net water loss from the body. The claim is that drinking more water will prevent the symptoms of dehydration—cramps, fatigue, headaches—often called Keto flu. 

This brand of hydration advice has roots its in the 1940s. That’s when the Food and Nutrition Board of the National Academy of Sciences recommended that adults drink 84 ounces of water per day.[*] This recommendation has since mutated into the 8x8 rule, which commands us to drink eight ounces of water eight times per day regardless of thirst.  

The 8x8 rule is widely accepted, but does any science suggest it promotes better health? No there isn’t, according to a meticulous review published in the American Journal of Physiology.[*

This doesn’t mean we shouldn’t drink fluids on Keto. But if we go beyond thirst, there can be undesirable consequences.

What’s Wrong With Drinking Too Much Water?

Over-hydrating with regular water dilutes blood sodium levels and increases the risk of a low sodium state called hyponatremia.

This is clear from the literature on endurance athletes.[*] A significent proportion of them suffer hyponatremia (due to overhydration) after the race, suffering symptoms like confusion, lethargy, headaches, and cramps. In severe cases, hyponatremia can lead to brain damage, seizures, and death. 

To be clear, severe hyponatremia is unlikely on a Keto diet. But minor cases of low sodium that show up as Keto flu symptoms are likely ubiquitous. 

Why do Keto folks tend to be low on sodium and other electrolytes? Contributing factors include: 

  • The overconsumption of plain water.
  • Increased sodium and potassium excretion through urine.[*]
  • Insufficient sodium or potassium intake. (A clean Keto diet contains scant sodium—it must be added through salt—and restricts potassium-rich foods like fruit and potatoes). 

So, what is the answer to hydration on Keto? 

How To Stay Hydrated on Keto

Proper hydration on Keto means following two basic rules:

  1. Drink to thirst
  2. Consume enough electrolytes 

When you drink to thirst, you prevent both dehydration and overhydration. You take in the perfect amount of water that your body needs. If you get tired of drinking plain water and find yourself struggling to consume enough to meet your hydration needs, consider adding small amounts of Keto-friendly fruit (berries, citrus peels etc) for a hint of flavor. 

Certain things—like elevation or hormonal imbalances—can throw off the thirst mechanism, but in general, thirst is a reliable indicator of hydration needs.[*

The other Keto hydration rule is to consume enough fluid-balancing electrolytes—sodium and potassium—through diet and supplements, if necessary. This means eating potassium-rich leafy greens, being liberal with the salt shaker, and possibly taking a well-formulated supplement. 

If you don’t fancy taking supplements but want to stay away from commercial electrolyte drinks with questionable ingredients, you’ll find a couple of delicious options in Carb Manager’s recipes database . If you feel like something warm and hearty, try this Keto Bone Broth recipe. For something light and refreshing, this Keto Tropical Electrolyte Drink is always a hit.

If you’re the data-driven type, you can also track your electrolyte intake with the Carb Manager app. What gets measured gets managed. 

Follow these simple rules and you’ll be setting yourself up to feel and perform your best on Keto. Happy hydrating. 

Comments 14

  • RemarkableAvocado956659

    RemarkableAvocado956659 3 years ago

    I thought I might be desaturating my sodium by overloading on water. I take in 5 bottles of 16oz each, every day. Not to mention 1 coffee and 2-3 green teas a day at 12oz each. Now I know to take salt also.

    • FabulousRadish259465

      FabulousRadish259465 2 years ago

      Note: green tea can block DAO production that breaks down histamine. Also, caffeine is a poison. The adrenaline rush is your body reacting to the poison. Lastly, if you need an energy boost, MCT oil is better, or hyperventilation will increase adrenaline too.

    • pricejap77

      pricejap77 2 years ago

      Use Himalayan Sea Salt

  • EZ_PZ_123

    EZ_PZ_123 3 years ago

    Is this ok if I drink carbonated water instead of a regular one? No flavors, just plain Pelligrino?

    • FabulousRadish259465

      FabulousRadish259465 2 years ago

      Yes that's better because it has no fluoride

  • Sabrina Pattison

    Sabrina Pattison 3 years ago

    I been on a can’t lose any weight ever since I get rid of my gallbladder at all,I been try to drink more water Can I drink crystals light for flavours

    • FabulousRadish259465

      FabulousRadish259465 2 years ago

      Take ox bile for gallbladder removal. You'll need to take it forever.

    • StupendousCauliflower594567

      StupendousCauliflower594567 3 years ago

      In the above article it says: If you are having a hard time to flavor your water. Add any non Calorie flavoring to your water so crystal lite is perfect. I add fresh lemon slices. Lemon aides in digestion and also helps your kidneys. I don’t have a gallbladder either and take super digest away. After years of suffering from not having a gallbladder. It’s been 3 years on this product and I’ve tried many other and keep going back to this because it works the best. Do your research and see if it’s right for you. I get it through Amazon but almost any natural health food store will carry it. Depending on how fat and protein I take 1 to 2. If it’s steak I take 2 right before meal time, sometimes I forget and take them right after. Read the reviews on Amazon. Hope this helps. Solaray Super Digestaway Digestive Enzyme Blend | Healthy Digestion & Absorption of Proteins, Fats & Carbohydrates | Lab Verified | 180 VegCaps

  • Tom

    Tom 3 years ago

    I hadn’t measured my glass for water and was consuming twice the amount. I feel a lot better now not having to get up at night. My cutoff time for water is usually 4pm.

    • Starchild

      Starchild 3 years ago

      I needed this advice will track my water

      • Keto mexican

        Keto mexican 3 years ago

        I drink a gallon a day, thanks this was informative.

        • GorgeousAvocado377641

          GorgeousAvocado377641 3 years ago

          Yes. It’s the big plastic milk container.

        • Sabrina Pattison

          Sabrina Pattison 3 years ago

          What’s a gallon is it like a plastic milk container

      • Reeniebh

        Reeniebh 3 years ago