Everything You Need to Know About Water Fasting

When I was diagnosed with prediabetes, I knew I had to make a change. I have 2 kids and I want to see them grow up. 

I tried water fasting a few times and noticed a difference. The next time I checked my A1C (blood sugar average over the last 3 months), it had gone down a bit! Nothing super dramatic, but definitely significant.

What Is Water Fasting, and What Are the Benefits?

This type of fasting (sometimes referred to as a water diet) is when you consume nothing but water for a given period of time, usually between 1 and 5 days. There are many reasons people may choose to fast, for example:

  • Spiritual reasons
  • Weight loss
  • Preparation for a medical procedure
  • Detox/boost immune function
  • Humanitarian or political reasons
  • Boost metabolism
  • Inhibiting chronic diseases


Fasting has been practiced for millennia, but it has only been used as a tool for preventing chronic disease in recent years.

1. Several studies have been conducted that found a correlation between intermittent fasting and a reduction in high blood pressure, coronary artery disease (CAD) and glucose intolerance.

While further research is needed, findings so far have been encouraging.

2. Another benefit is the promotion of autophagy. This is a biological process that rids the body of cellular and metabolic waste. It is known to help protect us from cancers, Alzheimer’s disease, diabetes and liver disease, among others.

3. Intermittent fasting has been associated with longevity and weight loss as well.

The weight lost during a fast is usually temporary, though. It is mostly water weight and it returns after you start eating normally again.

The caveat here is that much of the research has been done on animals or in short-term clinical trials. Further research is needed to solidify these correlations in humans.

How Do You Prepare to Go Without Food?

If you’ve never fasted before, some prep is in order. According to the findings in this 2015 study, we eat for upwards of 15 hours each day. 

Our bodies are used to having a constant stream of calories available!

Follow these steps to make the water diet less of a shock to your system:

1. Up your water intake right now

It sounds like a no-brainer, but since most of us are chronically dehydrated, this is an important first step. 

2. Gradually decrease what you eat

Ease into the fast by decreasing your caloric intake by about 20 percent each day for a few days. After you’ve completed your period of abstinence, gradually increase your calories back to a healthy amount for your body and lifestyle.

3. Have a Plan in Place to Encourage Success

You know what your weaknesses are. Do you tend to stress eat? Do you get ravenous at 3pm every day? Plan how you will counteract these challenges ahead of time. Perhaps an afternoon walk is in order, or you can make sure to stay away from the break room and vending machines.

What Should You Expect?

The very first time I fasted, it was for three days. I consumed only water. I really didn’t know what to expect because I hadn’t done any research or done any preparation. What surprised me the most during the fast was how normal it felt. Subsequent periods without eating didn’t go so smoothly though. Here are a few things you may experience:


The severity can vary, depending on what you normally eat and drink. Are you a coffee drinker? Do you consume lots of sugar? You may have a caffeine or sugar withdrawal headache for the first couple of days (mine hit me on Day 2).

Dry mouth and bad breath

Salivary glands that normally work full time helping to predigest your food are on vacation during the fast. This lets the anaerobic bacteria in your mouth have a heyday, causing the unpleasant side effect of halitosis. 

Your body is also ridding itself of toxins, adding to this negative side effect.

You can combat this one by brushing your teeth a couple times throughout the day and rinsing with baking soda water.


It’s natural to feel a bit tired by the end of your first day. Give yourself room to operate on a lower energy level than you are used to. Take a nap if you need to.

Blood pressure changes

Orthostatic hypotension (a drop in blood pressure when you stand from a seated position) is common. Be prepared for this and move slowly to avoid dizziness and feeling faint.

Lower back pain

Sudden abstinence from food can trigger a reflexive response from your kidneys, leading to lower back pain. This response should only last a couple of days. If it lasts longer, consult with your doctor.


This is a common symptom during the first couple of days when you are missing your regular mealtimes. 

Eating on auto pilot

You may find that you eat something, not because you can’t resist the urge, but as a force of habit. 

Do you normally reach for a candy when you pass the office receptionist’s desk? Do you usually have a bowl of cereal when you watch TV at night? Be mindful of your patterns so you don’t inadvertently sabotage yourself.

I found that I did fine during the day, but when I went to church in the evening, I had already eaten 3 mints before remembering I was fasting!

The benefit is that you realize the habits that you’ve fallen into without even knowing it, and you can address them accordingly (see the section on prayer and meditation below).

What Happens to Your Body When You Fast?

Your body goes through many metabolic and hormonal changes when you stop eating.

Gluconeogenesis starts

This is a normal function of your liver that goes into overdrive during a fast. 

Normally your cells use glucose from food to get the energy required to operate. When you stop eating, your liver has to generate sugar by metabolizing amino acids (protein), fats and lactate. 

The fatigue you experience is caused by this internal process that makes your body more efficient at how it uses energy.

One benefit of this process is the reduction of fat in the bloodstream as it is used for energy, and the resulting decrease in LDL (bad) cholesterol.

Ketosis begins

As your body goes even longer without consuming glucose, it goes into ketosis. This is a metabolic process during which your body uses mainly fat to get the energy it needs.

This is the concept behind the popular Keto Diet, and it is what encourages some of the weight loss you are likely to experience.

The healing process starts after about a week

This is when your digestive system has come to a stand still because it does not have to process the toxins associated with eating every day.

This means your immune system (which is located in your gut) has a chance to focus all of its efforts on cleansing itself and healing damaged tissues.

Balance occurs after about 2.5 weeks of abstaining from food

At this point, your body continues to cleanse and heal.

Fasts this long should only be completed under the supervision of a health professional to mediate the associated risks.

What Should You Do During A Fast?

For short-term abstinence from food, you should be able to maintain your regular routine. If your normal work requires consuming calories for safety reasons, plan your fast for when you will be off work for a few days. Other things you may want to do include:

  • Pray or meditate Even if you are not doing the fast for spiritual reasons, now is the perfect time to get in the zone. The time you would otherwise use for meal prep and eating can be used to focus on what means the most to you.
  • Stay active Now is not the time to reinstate that fitness routine that fell by the wayside on January 15th, but an easy stroll outside for fresh air and circulation can lift your mood if you are starting to feel hungry.

How Often Should You Fast?

While you may notice benefits quickly like I did, the best results may come from routinely fasting over time. 

Dr. Alan Goldhamer, DC is the education director of the TrueNorth Health Center. In a 2014 interview for Integrative Medicine: a Clinician’s Journal, he stated:

“…to arbitrarily say, ‘I am going to fast 1 day a week’ and think that I am getting proportional clinical benefits to those of a longer fast done once or twice a year would turn out to be a mistake—although the research we are doing will hopefully elucidate further exactly what is going on.”

What Are the Risks of the Water Diet?

Not everyone’s body is suited for a water diet. Consult with your doctor prior to starting. It may be that you can fast, but for a shorter amount of time. 

  • Children
  • Pregnant/nursing women
  • People with low blood pressure
  • People with gallbladder issues
  • People with gout
  • Type 1 diabetics
  • People with a compromised immune system

Even relatively healthy people can experience adverse effects, usually while doing a fast longer than 5 days. Some risks of consuming only water for extended periods of time include:

  • Dehydration from increased urination
  • Electrolyte imbalance
  • Cognitive sluggishness
  • Adverse neurological effects

What Is the Best Way to End Your Fast?

How you complete your fasting period is just as important as the preparation beforehand. Eating a full meal on day one will lead to digestive distress (nausea, vomiting, cramping) and pain. 

This is because your digestive system uses enzymes, mucus, acids and hormone-induced processes to break down and move your food. While you weren’t eating anything, these processes basically came to a standstill. 

Breaking your fast with a full meal would be similar to driving your car with no engine oil. It can be done, but it won’t be good for anyone involved.

Slowly introducing food lets your body’s processes restart at a natural rate.

Another reason to gradually introduce food back into your daily diet is to be more mindful about what you eat.

Otherwise, what was the point, right?

Hopefully over the course of the fast you became more aware of how you relate to food and any changes you may want to make. 

Aim to break the fast in half as many days as the fast took. Did you abstain for 4 days? Take 2 days to return to a normal diet.

In general, foods should be reintroduced according to this order:

  1. Fruit and veggie juices
  2. Fresh fruit
  3. Veggie broth
  4. Plain yogurt or other fluids with probiotics
  5. Spinach and lettuce
  6. Cooked veggies and veggie-based soups
  7. Fresh veggies
  8. Grains and legumes
  9. Eggs and nuts
  10. Dairy
  11. Meats

As you move down the list, chew your food well and be aware of how you feel after each new reintroduction. You may need to stay at one level a bit longer before moving on.


Water fasting is challenging, and it doesn’t come without risks. But with careful planning, preparation and knowing what to expect, it can be a routine part of an overall healthy lifestyle.

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