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Water Intake on Keto: How Much Do You Need?


It’s the MOST COMMON substance on earth, and yet we have such a hard time getting enough of it. Keto presents some of its OWN unique challenges in regard to water intake. Before we get into it, I thought I’d start off with a few interesting facts about water. Because… why the heck not!?

Did you know?

  • 85% of the world population lives in the driest half of the planet.
  • Only 1% of the water available on earth is suitable for drinking. [*]
  • 75% of the weight of the human body is water molecules.
  • We can live at most 4–5 days without water at room temperature. [*]

Experts often disagree about how much water we actually need to drink. But, one thing I can say for sure is that the ketogenic diet requires MORE fluids than a standard high carb diet. With keto, we tend to flush both fluids AND electrolytes more freely. This means we have an increased need for water intake on keto.

Becoming dehydrated is surprisingly easy to do on the ketogenic diet. And, it isn’t exactly a fun experience in my opinion. It’s known to reduce mood, lower concentration, and harm other cognitive performance markers.

Interestingly, there is a protein that signals us to drink more water when we are in ketosis. [*]. Sometimes I wonder if that is actually working as well as it should.

Let’s take a look at the big picture.

How much water you should be consuming on a ketogenic diet infographic

Loss of Water Through Glycogen

There is a big difference with the physiology of our muscles when we’re in ketosis. We no longer have all that glycogen stored up. Our bodies use it up over the course of a few days and our stores run low.

But here is the interesting thing. Water ALSO leaves our bodies with the glycogen. For each gram of glycogen lost, we also lose about 3 to 4 grams of water. That adds up fast! This is a big reason why we need to adjust our water intake on keto.

A typical 80kg male has about 500g of glycogen total in his body. That would equate to about 3.3 pounds of water loss. On the ketogenic diet, we can lose anywhere from 3 to 10 pounds in water weight. This will fluctuate over time. Eating ANY amount of carbs will cause that water weight to come back. [1]

The important thing to remember here is that we are losing water EASILY on the ketogenic diet.

We need to increase our water intake on keto to avoid fatigue and other symptoms.

How do we fix glycogen related water loss? 

  • Hydrate! Hydrate! Hydrate!

Loss of Electrolytes

There is a process that takes place in the body once you restrict carbs below 60g/d. It’s called the “Natriuresis of Fasting”. The NoF causes the body to flush electrolytes through the kidneys. At first, this is mostly sodium. Then, In the process to conserve whatever sodium it can, the body uses up POTASSIUM stores also. Now, we have a big problem.

We have now lost quite a bit of water AND ALSO sodium and potassium. They’re ALL needed for maintaining proper circulation! And, guess what?  This scenario is known to create the famous “keto flu” that you are probably familiar with. It is an electrolyte imbalance.

In studies where scientists have measured the athletic performance of keto athletes, they have supplemented them with 5g of sodium daily (from all sources). That is TWICE the daily recommended intake by the FDA. But hey, that’s okay!  Keep in mind our bodies are naturally lowering blood pressure on the ketogenic diet. We need the salt. [3]

What can we do about Electrolyte Loss?

  • Add a pinch of pink Himalayan salt to your water throughout the day
  • Consume Green leafy veggies for the potassium and magnesium.
  • Salt your food to taste (up to 5g sodium per day is good)

How Much Water Should I Drink on Keto?

That bottom line is that you need to INCREASE your water intake on keto.

Generally, the eight by eight rule for cups of water per day is a good start. But, everyone’s needs are different. That rule would generally not be enough for most people.

The Mayo Clinic is now recommending

  • Men – 100oz of water per day
  • Women – 73oz of water per day

Note: These amounts are separate from food which consists of about 20% of your daily water intake.

Now, these are very general guidelines and they DO NOT take into account the ketogenic diet NOR do they take into account exercise. But, use them as a point of reference.

Some ketogenic health experts are recommending up to 140oz or even higher per day. In my experience, I would start on the conservative side and work your way up.

Use “how you feel” as a guiding measure for your water intake on keto.

Here’s my two sense.

For MEN on keto, I would recommend:

  • Starting at 120oz per day (That’s 3.75 Nalgene bottles).
  • Ensure your sodium and potassium are in check.
  • If you feel fatigued, Move up to 140oz.

For WOMEN on keto, I would recommend:

  • Starting at 90oz per day (That’s 2.8 Nalgene bottles).
  • Ensure your sodium and potassium are in check.
  • If you feel fatigued, Move up to 100–110oz.

If you are spending time outside in the heat, your need for water is going to be higher that day. Exercise is also going to play an important role.

Warning: Do not drink more water than what you feel is necessary. Over-hydration will cause your body to flush electrolytes and other minerals. It is important to find the right balance for YOU.

What are the Benefits of Drinking More Water?

The benefits of drinking water are numerous. From the various cognitive benefits such a mood enhancement and increased focus to kidney stone prevention, water boosts our health in considerable ways.

Here are a few reasons why you want to be keeping an eye on your water intake on keto.

1. Mood

Studies have shown that drinking water can improve your mood. Even a small amount of dehydration can have adverse effects on mood. [*]

2. Brain Function

Several studies have shown that drinking water can maintain better short-term memory and attention. [*] [*]

3. Alertness

It was observed in a study that restricting water reduced alertness and concentration. [*]

4. Physical Performance

One study showed that drinking water can increase athletic performance. This is in specific reference to VO2 max. Your VO2 max is the amount of oxygen you can use during intense exercise. [*]

5. Weight Loss

A 2003 study found that drinking an additional 1.5L per day of water could increase calories burned daily by 47. [*] It was also found that people who drank water before a meal, consumed fewer calories per day. [*] [*]

6. Bladder Cancer

One study found that higher fluid intake correlated to lower risks of bladder cancer in men. [*]

7. Kidney Stones

Several studies have found that drinking water may reduce the risk of kidney stones. [*] [*] [*]

8. Various Diseases

A 2017 study made the connection that dehydration could indirectly promote various diseases. These include metabolic syndrome, coronary artery disease, heart failure, vascular dementia, cognitive impairment, chronic kidney disease, cancer, and premature mortality. [*] Wow!

Tips For Managing Water Intake On Keto

As I mentioned, consuming as much water as you can is NOT the solution, NOR is it SAFE. But generally, it can be hard to consume the recommended amount. We need to make a conscious effort to meet our daily goal.

If you are experiencing fatigue, headaches, or muscle weakness, drink a glass of water with a pinch of Himalayan salt. If you aren’t experiencing these symptoms, you are likely doing just fine with your current fluid intake.

Use urine color to determine your hydration status. Dark yellow urine indicates dehydration pretty accurately. [*]

Carry a water bottle with you wherever you go. Sip on it throughout the day. Having it near you will serve as a reminder that you need to get more water in your system. I carry my Nalgene bottle with me all day long. I know that I need to fill it up about 4 times a day, so that is my goal.

Limit the use of diuretics such as coffee and tea. These are going to increase the amount of fluid you are flushing through your kidneys. Trust me, I am a huge coffee drinker and enjoy several cups a day. But, coffee is no substitute for a glass of water in terms of keeping you hydrated.

What is YOUR Water Daily Water Intake on Keto?

Let us know in the comments below!

Offline Sources

[1] Art and Science of Low Carbohydrate Living Chapter 4

[2] Art and Science of Low Carbohydrate Living Chapter 2

[3] Art and Science of Low Carbohydrate Living Chapter 12

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