Water Fasting To Get Into Ketosis

Water fasting induces ketosis. Burn more fat, reduce inflammation, decrease appetite when fasting for ketosis.
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Add a water fast to your intermittent fasting routine once a month or a few times a year to boost your weight loss efforts and improve your general physical health and mental well-being. Attempt one to three days of water fasting to induce ketosis. This allows your body to start burning fat, which fuels the body and the brain. When you allow your body time to rest, rejuvenate, and heal, you will feel energized, focused, and less hungry.

Written by
Jill Lebofsky
15+yr Women's Wellness Expert, Holistic Menopause Support, Intermittent Fasting, Midlife, Essential Oil, Author, Speaker

You have probably heard of the Ketogenic (Keto) plan for losing weight. It is based on eating an extremely low carbohydrate/high-fat diet that allows the body to burn stored fats for energy. Fasting can accomplish the same results but quicker. The longer you fast and stay in ketosis, the greater the benefits received.


What is ketosis?

When you regularly eat at short intervals, your body becomes dependent on glucose (a type of sugar) to stay fueled and functioning. If this source of energy is depleted, your body enters a state of ketosis. Small molecules called ketones that have been converted from stored fat in the body are used as a new, alternate source of energy for both the body and the brain (1). One of the many ways the body can reach ketosis is through fasting.


Benefits of ketosis

Much of the research on the benefits of ketosis is based on low-carb diets. Fasting is no carbs; therefore, one will find similar results for fasting and ketosis.

Women doing stretch exercises.

Decreased appetite

Ketosis may suppress appetite due to a decrease in the hunger hormone ghrelin (2).

Body shape changes 

In the state of ketosis the body burns stored fat, and if the body can attain and stay in this state for more extended periods, it results in inches and pounds lost.

Reversal of diabetes and prediabetes

Ketosis can help improve insulin resistance and stabilize blood sugar levels (3).

Improved endurance and performance during exercise 

Once your body is keto-adapted, burning fat for fuel can support longer, more intense workouts (4).


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Fasting and ketosis

As mentioned, ketosis relies on glucose levels dropping low enough for the body to produce ketones, causing it to switch to stored fat as its primary source of energy. This is precisely what happens during intermittent fasting, whether following the 16/8, the 5:2, the alternate day, or any other method of intermittent fasting.

These methods start the ketosis process and are great choices to adopt as a permanent lifestyle for the long-term benefits. If you want to reach full ketosis and stay there for a while to reap the benefits, prolonged fasting, sometimes referred to as water fasting, is necessary.

How long does it take to go into ketosis when fasting?

The length of time it takes for fasting to induce ketosis varies between people. It depends on many factors, including how often you eat, your activity level, and the number of carbs you consume. The beginning of intermittent fasting ketosis can start after 12 hours for some people. By 24-48 hours, the body is reaping the full benefits of ketosis (5).


Water fasting

Most intermittent fasting methods schedule fasting periods of less than 24 hours. Water fasting takes it up a notch, eliminating all food and allowing the drinking of water-only for 1-3 days. It is essential to consume at least 2-3 liters of water per day. Although people do longer water fasts, you should not extend a water fast beyond 3 days without medical supervision. Some people do a water fast once a month, others a few times a year.


Water fasting to induce ketosis

Water fasting allows the body to enter the state of ketosis more quickly than through Keto or another low-carb diet. All food is withheld. Therefore, the body depletes its energy source sooner and turns to ketones and fat burning to keep it running.


Water fasting benefits

Water with lemon and mint.

The positive outcomes of water fasting are the same, but at an increased level, as the benefits of intermittent fasting. They include decreased insulin resistance, improved cardiovascular and brain health, and increased production of the “anti-aging” human growth hormone (HgH).

Water fasting also enhances autophagy, the body’s natural cell cleaning and recycling system, reducing oxidative stress and inflammation.

Water fasting can help with weight loss, especially when practiced regularly. But prolonged fasting of more than three days is more beneficial in this regard (6).

Also, consider adopting an intermittent fasting lifestyle for the long term, possibly pairing it with Keto or a low carbohydrate diet to obtain and maintain the desired results.


Safety Considerations

People with eating disorders, pregnant women and children under 18 should avoid water fasting.

Water fasting can help with gout and type 1 or 2 diabetes, but people with such a medical condition should practice water fasting only under medical supervision.

It is normal to feel irritable, but if you start to feel disoriented or confused, stop immediately and seek medical advice.

Short-term water fasting doesn’t cause nutritional deficiencies, but you could find yourself lacking in vitamins, minerals, or protein if you are doing them frequently. Space out your fasts and take the appropriate supplements for fasting.



Water fasting helps one enter ketosis more quickly than other ways of reaching this metabolic state. The body is wholly deprived of nutrients, so it turns to its own fat stores for energy. Adding in a water fast to your routine for a few days to induce periodic ketosis has many long-term benefits for physical and mental health, including reducing inflammation, decreasing insulin resistance, and increasing energy levels and mental clarity.  Best weight loss results may be achieved with medically supervised, prolonged fasting of more than 3 days.


1. Masood W, Annamaraju P, Uppaluri KR. Ketogenic diet. Treasure Island (FL): StatPearls Publishing (Internet); 2020 Dec 14. https://www.ncbi.nlm.nih.gov/books/NBK499830/

2. Sumithran P;Prendergast LA;Delbridge E;Purcell K;Shulkes A;Kriketos A;Proietto J; Ketosis and appetite-mediating nutrients and hormones after weight loss. European journal of clinical nutrition. 2013 Jul;67(7):759-64. doi: 10.1038/ejcn.2013.90

3. Furmli, Suleiman, et al. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin.” BMJ Case Reports, BMJ Publishing Group, 2018 Sept 18. casereports.bmj.com/content/2018/bcr-2017-221854.

4. Cox, Pete J, and Kieran Clarke. Acute nutritional ketosis: implications for exercise performance and metabolism. Extreme Physiology & Medicine. 2014;(3)17. doi:10.1186/2046-7648-3-17

5. Bergqvist, A. G. Christina, et al. “Fasting versus gradual initiation of the ketogenic diet: a prospective, randomized clinical trial of efficacy.” Epilepsia. 2005 Nov 2;(46)11:1810-1819. doi.org/10.1111/j.1528-1167.2005.00282.x

6.  Gilliland, IC. Total fasting in the treatment of obesity. Postgrad Med J. 1968;44(507):58-61. https://pmj.bmj.com/content/postgradmedj/44/507/58.full.pdf

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