Keto and Dehydration: How Much Water Should You Drink?

Keto and dehydration are common topics for people in the initial phase of the keto diet. The metabolic change in the body during ketosis causes fluid loss, which may result in dehydration. This comprehensive article will discuss why this happens, its signs and symptoms, and how to avoid getting dehydrated while on keto.

Key Takeaways:

  • The keto diet lowers insulin levels, causing your body to reduce water depots and flush out water.
  • An average person should drink 75 fl oz water daily to maintain hydration on keto.
  • Drink water and other fluids and consider water-rich foods, electrolyte-rich foods, and supplements.
  • Avoid caffeine, alcohol, and spicy foods to prevent dehydration on keto.

Table of Contents:

Does Keto Cause Dehydration?

Keto may cause dehydration in some people, especially when the water intake is minimal. This phenomenon happens due to the following reasons.

Glycogen Depletion

In the initial stages of adopting a ketogenic diet, the body significantly reduces carbohydrate intake, forcing glycogen use. Each gram of glycogen holds 3 grams of water.1 

When using glycogen, the water molecules get released, causing water loss. This water weight loss is the initial weight loss observed with the keto diet.

Diuretic Effect and Decreased Water Retention

The ketogenic diet decreases insulin levels. With lower insulin levels, the kidneys release sodium,2 causing increased sodium and water excretion. This diuretic effect can contribute to fluid loss and the potential for dehydration.

Electrolyte Imbalance

Keto-induced changes in insulin levels and increased diuresis can disrupt electrolyte levels,3 including sodium, potassium, and magnesium. 

Their imbalance can lead to cellular dehydration,4 affecting various physiological functions and potentially contributing to dehydration symptoms.

Increased Physical Activity

Individuals adopting the ketogenic diet often engage in increased physical activity to enhance fat-burning and weight loss. 

Higher activity levels, particularly with limited carbohydrate intake, can result in elevated sweat production.5 Sweat contains water and electrolytes, contributing to fluid loss and the need for additional hydration to prevent dehydration.

Dehydration Symptoms on Keto

Keto dehydration manifests more than feeling thirsty. Here are some of the signs of symptoms that you need to up your hydration:

1. Excessive Thirst

Dehydration triggers the brain’s thirst mechanism as a compensatory response.6 As water levels decrease, the body signals an increased desire to drink through thirst.

2. Dry Mouth and Throat

Inadequate fluid intake and dehydration lead to reduced saliva production.7 Saliva acts as a natural lubricant for the mouth and throat. Insufficient moisture can result in a dry and sticky sensation, often leading to a smelly breath.

3. Dark Urine Color

Dehydration reduces the volume of urine produced, causing it to contain more urine pigments known as urochrome.8 

4. Dry Skin

The skin, the largest organ in the body, is one of the first to manifest dehydration. The skin needs about 10-15% water content to remain supple and intact.9 

Dehydration diminishes skin elasticity and moisture, leading to dryness, flakiness, and potentially exacerbating conditions such as eczema and psoriasis.

5. Muscle Cramps or Spasms

Sodium, potassium, and magnesium are crucial for proper muscle function. The possible electrolyte imbalance during dehydration can contribute to muscle cramps and spasms. 

6. Fatigue and Weakness

Dehydration diminishes blood volume,10 decreasing oxygen delivery to muscles and organs. As a result, individuals may experience fatigue and weakness. Additionally, inadequate hydration impairs the body’s ability to convert nutrients into energy.

7. Headache

Dehydration causes a reduction in cerebral blood flow and oxygen delivery to the brain, potentially leading to headaches.11 Additionally, electrolyte imbalances can contribute to vascular changes, triggering headache symptoms.

8. Constipation

Insufficient water intake hampers the digestive process,12 leading to harder and drier stools, making them difficult to pass. 

9. Brain Fog

Aside from headaches, dehydration also affects cognitive function,13 leading to difficulties in concentration, memory, and mental clarity.

How Much Water Should You Drink on Keto?

The amount of water intake depends on various factors. However, as a rule of thumb, you must divide your weight in half and drink that many ounces of water daily. This means that if you weigh 150 pounds, you must drink about 75 ounces of water.

Generally, one should take about 64 ounces of water daily.14 However, with the increased water loss during keto, you may need to drink more.

Experts may have different opinions on how much water to drink, but listening to your body’s changes and reactions is crucial. Familiarize yourself with the abovementioned signs and symptoms and adjust your intake accordingly. 

Drinking enough water will keep you hydrated and prevent you from overeating. It’s a win-win situation. 

How to Stay Hydrated on the Keto Diet

keto and dehydration

1. Drink Water

Water is the cornerstone of proper hydration. You can bring bigger water bottles or buy more appealing ones to ensure you drink enough water daily. Some water bottles also have markings to keep you motivated on your progress.

2. Increase Other Keto Fluids

You can increase hydration by drinking herbal teas, broths, keto energy drinks, flavored water, and other keto-friendly beverages. If you want more flavors, check the label for added sweeteners when buying drinks.

3. Incorporate Electrolyte-Rich Foods

Electrolytes, including potassium, magnesium, and sodium, are crucial for hydration. In keto meals, electrolyte-rich foods like avocados, leafy greens, nuts, and seeds support electrolyte balance.

4. Eat Water-Rich Foods

Cucumbers, watermelon (in moderation), and celery have high water content and contribute to overall fluid intake while aligning with the low-carbohydrate principles of the ketogenic diet.

5. Consider Electrolyte Supplements

Consult your healthcare provider and consider adding electrolyte supplements, especially during the initial keto phase, where dehydration symptoms are most common. 

6. Consider Fluid Tracking Apps

Consider tracking apps to remind you of your fluid intake. These apps help set hydration goals, provide reminders, and offer insights into your hydration habits. 

Hydrating Keto Foods with Electrolytes

There are a bunch of keto-friendly foods that are hydrating and rich in electrolytes to help you prevent dehydration. Here are the most common ones:

Food (100 g)WaterPotassiumSodiumMagnesium
Avocado73%485 mg7 mg29 mg
Strawberries91%153 mg1 mg13 mg
Blackberries88%162 mg1 mg20 mg
Blueberries85%77 mg1 mg6 mg
Raspberries86%151 mg1 mg22 mg
Watermelon92%112 mg1 mg10 mg
Cantaloupe89%267 mg16 mg12 mg
Oranges87%181 mg1 mg10 mg
Lemon89%138 mg2 mg8 mg
Lime88%102 mg2 mg6 mg
Mushroom92%318 mg5 mg9 mg
Cucumber95%147 mg2 mg13 mg
Lettuce95%194 mg5 mg13 mg
Zucchini94%280 mg8 mg18 mg
Cauliflower92%299 mg30 mg15 mg
Cabbage92%170 mg18 mg12 mg
Broccoli89%316 mg33 mg21 mg
Spinach91%558 mg79 mg79 mg
Kale84%491 mg38 mg47 mg
Collard Greens90%213 mg47 mg33 mg
Coconut Water94%250 mg105 mg25 mg
Cottage Cheese80%81 mg364 mg9 mg
Greek Yogurt81%141 mg50 mg11 mg

Foods and Drinks to Avoid

While increased hydration is necessary, you must avoid some foods to prevent further fluid loss. 

1. Caffeine

Caffeine, commonly found in coffee and tea, has diuretic properties15 that can increase urine production. While moderate caffeine consumption is generally acceptable on keto, excessive intake may contribute to fluid loss.

2. Alcohol

Alcohol is dehydrating and can interfere with the body’s water balance. The diuretic properties of alcohol16 can lead to increased urine output, potentially exacerbating dehydration.

3. Spicy and Acidic Foods

Spicy and acidic foods irritate the bladder, urging it to release urine more frequently. This results in increased fluid loss.

4. Other Foods with Diuretic Effects

Asparagus, celery, parsley, dandelion, and spices often have diuretic effects. Too much of these may result in increased fluid loss.

Contrary to popular belief, you do not have to fear salt on a keto diet. Due to lower insulin levels, your kidneys will excrete more sodium17 than if you eat a Standard American Diet.

Therefore, sodium intake helps you maintain healthy electrolyte levels and retain fluid in the body.

The Bottom Line

Dehydration during keto is common and could be responsible for some of the keto flu symptoms. However, increasing your hydration and electrolyte intake through water, supplementation, and foods helps mitigate this.

Avoiding caffeine, alcohol, and spicy foods is essential to maintaining hydration. 

Frequently Asked Questions (FAQ)

How do you fix dehydration on keto?

Ensuring enough water intake, adding electrolytes to your fluids, and prioritizing hydrating and electrolyte-rich foods are the most effective ways to fix dehydration on keto. 

What happens if you don’t drink enough water on keto?

Not drinking enough water during keto increases your risk of developing kidney stones and worsens keto flu symptoms, including fatigue, headache, dryness, and muscle spasms. 

Does a low-carb diet dehydrate you?

Yes, a diet low in carbohydrates decreases glycogen stores, releasing body fluid. This increases urine output and possibly causes dehydration. 

Is dehydration a side effect of keto?

Yes, dehydration is a common side effect of keto, but it is the easiest to combat. Just ensure taking enough water and electrolytes to help mitigate this side effect. 

References

1Fernández-Elías, V. E., Ortega, J. F., Nelson, R. K., & Mora-Rodriguez, R. (2015). Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans. European journal of applied physiology, 115(9), 1919–1926. https://doi.org/10.1007/s00421-015-3175-z

2Brands, M. W., & Manhiani, M. M. (2012). Invited Review: Sodium-retaining effect of insulin in diabetes. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, 303(11), R1101. https://doi.org/10.1152/ajpregu.00390.2012

3Shrimanker I, Bhattarai S. Electrolytes. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541123/

4Disturbances of Free Water, Electrolytes, Acid-Base Balance, and Oncotic Pressure. Veterinary Medicine. 2017:113–52. doi: 10.1016/B978-0-7020-5246-0.00005-X. Epub 2017 Feb 10. PMCID: PMC7149330.

5Baker, L. B. (2017). Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Medicine (Auckland, N.z.), 47(Suppl 1), 111-128. https://doi.org/10.1007/s40279-017-0691-5

6Adams, W. M., Vandermark, L. W., Belval, L. N., & Casa, D. J. (2019). The Utility of Thirst as a Measure of Hydration Status Following Exercise-Induced Dehydration. Nutrients, 11(11). https://doi.org/10.3390/nu11112689

7Ship, J. A., & Fischer, D. J. (1997). The relationship between dehydration and parotid salivary gland function in young and older healthy adults. The journals of gerontology. Series A, Biological sciences and medical sciences, 52(5), M310–M319. https://doi.org/10.1093/gerona/52a.5.m310

8Belasco, R., Edwards, T., Munoz, A. J., Rayo, V., & Buono, M. J. (2020). The Effect of Hydration on Urine Color Objectively Evaluated in CIE L*a*b* Color Space. Frontiers in Nutrition, 7. https://doi.org/10.3389/fnut.2020.576974

9Pons-Guiraud A. (2007). Dry skin in dermatology: a complex physiopathology. Journal of the European Academy of Dermatology and Venereology : JEADV, 21 Suppl 2, 1–4. https://doi.org/10.1111/j.1468-3083.2007.02379.x

10Taylor K, Jones EB. Adult Dehydration. [Updated 2022 Oct 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK555956/

11Arca, K. N., & Halker Singh, R. B. (2021). Dehydration and Headache. Current Pain and Headache Reports, 25(8). https://doi.org/10.1007/s11916-021-00966-z

12Arnaud M. J. (2003). Mild dehydration: a risk factor of constipation?. European journal of clinical nutrition, 57 Suppl 2, S88–S95. https://doi.org/10.1038/sj.ejcn.1601907

13Zhang, N., Du, S. M., Zhang, J. F., & Ma, G. S. (2019). Effects of Dehydration and Rehydration on Cognitive Performance and Mood among Male College Students in Cangzhou, China: A Self-Controlled Trial. International Journal of Environmental Research and Public Health, 16(11). https://doi.org/10.3390/ijerph16111891

14Armstrong, L. E., & Johnson, E. C. (2018). Water Intake, Water Balance, and the Elusive Daily Water Requirement. Nutrients, 10(12). https://doi.org/10.3390/nu10121928

15Zhang, Y., Coca, A., Casa, D. J., Antonio, J., Green, J. M., & Bishop, P. A. (2015). Caffeine and diuresis during rest and exercise: A meta-analysis. Journal of Science and Medicine in Sport / Sports Medicine Australia, 18(5), 569. https://doi.org/10.1016/j.jsams.2014.07.017

16M. Polhuis, C. M., C. Wijnen, A. H., Sierksma, A., Calame, W., & Tieland, M. (2017). The Diuretic Action of Weak and Strong Alcoholic Beverages in Elderly Men: A Randomized Diet-Controlled Crossover Trial. Nutrients, 9(7). https://doi.org/10.3390/nu9070660

17Gupta, A. K., Clark, R. V., & Kirchner, K. A. (1992). Effects of insulin on renal sodium excretion. Hypertension (Dallas, Tex. : 1979)19(1 Suppl), I78–I82. https://doi.org/10.1161/01.hyp.19.1_suppl.i78

Mag. Stephan Lederer, MSc.

Mag. Stephan Lederer, MSc. is an author and blogger from Austria who writes in-depth content about health and nutrition. His book series on Interval Fasting landed #1 on the bestseller list in the German Amazon marketplace in 15 categories.

Stephan is a true man of science, having earned multiple diplomas and master's degrees in various fields. He has made it his mission to bridge the gap between conventional wisdom and scientific knowledge. He precisely reviews the content and sources of this blog for currency and accuracy.

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