How to Prepare for Fasting

Last Updated: July 30, 2021 References Approved

Fasting is a method in which people eliminate all foods and drinks from their diet for a specific period. People fast to clean their digestive systems, to lose weight and, in some cases, for spiritual or religious purposes. There are steps you can take to properly prepare your body for the sudden, drastic change in diet during a fast. See step 1 to get started preparing for your fast.

Part 1

Part 1 of 3:

Learning About Fasting

1
Consult with your doctor or health care provider before fasting. There are lots of great reasons to fast, even if you don't have a medical condition, but there are potential health risks involved and it's something you should discuss with a licensed professional before jumping off into the deep end of fasting.^{[1]
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Expert Source

Lyssandra Guerra
Certified Nutrition & Wellness Consultant
Expert Interview. 25 March 2020.}
- Some medications you take may have dangerous effects on your body during fasting due to changes in your blood chemistry.
- Fasting may not be ideal for people experiencing health conditions such as pregnancy, advanced cancer, low blood pressure and more. If you have any medical condition, you should check with your doctor before fasting.
- Your doctor may want to conduct a urine test or blood test before the fasting period.
2
Determine the type and length of fasting you want to practice. There are hundreds of different fasting practices. Some include just drinking water, some include drinking juices (or clear liquids), some are for spiritual reasons, or for weight-loss reasons, or to help with a medical condition. You'll need to sort out which is the best choice for you.^{[2]
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Cleveland Clinic
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- Water fasting is a more aggressive type of fasting and one of the harder types. You can do it anywhere from 1 to 40 days (although 40 is definitely pushing it and not recommended without a doctor's approval). Water fasting can be dangerous to your health both while fasting and while ending the fast. You'll need to begin and end with a couple day juice diet.^{[3]
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- The juice fast is one of the safer bets for fasting, because you're still getting nutrients from the juices you're drinking, so it isn't as aggressive as the water fast and is more recommended. 1 to 10 days is the standard for a juice fast. You'll want to drink all-vegetable and all-fruit juices and you can have herbal teas and vegetable broth as well. ^{[4]
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- The Master Cleanse is a fast that is a mix between the water fast and a juice fast. You drink a mixture of freshly squeezed lemons, water and maple syrup for about 10 days. This is an easier fast because you will still be getting some calories (although not as many as you are used to).
- Fasting periods can last anywhere from 1 to 40 days, depending on your specific goal and the kind of fast you're doing (juice fast, water fast, clear liquid fast, etc) because this will determine how your body is coping with having most of its calories taken away.
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3
Prepare for the changes that may occur in your body. Fasting is about eliminating the toxins that have built up in your body (it will do this even if you're fasting for religious or spiritual reasons) so you're going to need to be prepared for feeling ill and weak, especially at the beginning.
- Fasting may cause side effects such as diarrhea, fatigue and weakness, increased body odor, headaches and more as a result of the detoxification process.
- Consider taking time off from work or relaxing more throughout the day to accommodate the effects fasting has on your body.

Part 2

Part 2 of 3:

Preparing to Fast

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Reduce your intake of all habitual and addictive substances 1 to 2 weeks before fasting. The more you reduce the garbage that you intake the easier the fast will be on you and your body. So gradually stop drinking alcohol and try to cut down on or stop entirely smoking.^{[5]
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- This procedure will reduce any potential withdrawal symptoms you may experience during the fasting process, as well as reduce the toxins in your body that the fast is going to work to eliminate.
- Habitual and addictive substances include alcohol; caffeinated beverages such as coffee, tea and soda; cigarettes or cigars.
2
Alter your diet 1 to 2 weeks before fasting. As with removing addictive substances you're going to need to make a different in your diet so that you can adjust to the fast easier.
- A good way to ease into this, is to eliminate a few things a day (refined sugar products in the first couple days, meat in the next couple, and then dairy, etc.).
- Reduce your intake of chocolate and other foods that contain refined sugar and are high in fat, like sodas, chocolate, candy and baked goods.^{[6]
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  National Health Service (UK)
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- Eat smaller portions of meals so that your digestive system doesn't have to work as hard, and so that your body starts to become accustomed to operating on fewer calories than it usually does.
- Reduce your intake of meats and dairy products.
- Eat increased portions of cooked or raw fruits and vegetables.
3
Limit your diet 1 to 2 days before fasting. This is when you really want to make sure that your body is prepared and this is why people can't just jump into a fast without preparing ahead of time (or if they do, they have a much harder time during the fast itself).
4
Drink lots of liquids. Drink only water, fruit and vegetables juices made from fresh, raw fruits or vegetables. You'll need to up your liquid intake during the pre-fast to help keep your system hydrated and prepare it for being only on liquid for awhile.
5
Get moderate exercise. You don't want to do too much exercise, but you definitely will need to do some to make sure the lymphatic fluid keeps moving and keep the vascular system working properly. Do some slow yoga, or go for a moderate walk.^{[7]
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- You're going to feel tired, even on the pre-fast diet, so be aware of that, but don't worry about it. Just adjust your normal levels of activity to accommodate that tiredness.
6
Get lots of rest. Whether you get enough sleep and rest is going to determine how well you do on the fast and how well you recover afterwards. Make sure that you're getting enough sleep at night and make sure that you're taking it easy during the day.
- This is why it's best to plan ahead for a fast, instead of jumping in headfirst. You'll need time to recover and to rest and so you'll need to make sure that you aren't having a super busy schedule.

Part 3

Part 3 of 3:

Knowing What to Expect

1
Make sure you know the physical effects you'll experience. The fast tends to be most uncomfortable and difficult during the first couple days and those are usually the days when people give up, but if you power through them, you'll probably start to feel better from day 3 onwards, with occasional bouts into discomfort.^{[8]
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- In the first stage (usually days 1 and 2) of the fast you may experience headaches, dizziness, nausea, bad breath, and a heavily coated tongue. You'll probably also be incredibly hungry during this stage.
- In stage 2 (about days 3 to 7, depending on the fast)) your skin might become oily and you might start breaking out a little, but your body should start adjusting to the fast. Your sinuses might go from clogged to clear several times.
- Eventually, in later stages, your bowels will release their load, which can come as diarrhea or loose stool and can contain lots of mucus, especially as you don't put anything into your body for several days. Your breath will keep smelling bad. You will also probably continue to experience low energy, as your body has fewer (or no) calories to keep it going.
2
Sustain your fast. A lot of times people give up in the first couple days, because of discomfort and they think that it won't get better. Unless you're having a serious medical issue (which you'll need to talk to your doctor about), breaking your fast before the finish won't benefit your body at all. There are a few things to do to make sure that you complete your fast.
- Set your objective. Before you start to fast, make a clear statement on why you're doing this fast. Is it for health reasons? Is it for religious reasons? Are you trying to clear your system out? Make this a clear statement and remind yourself of your objective in the hard moments of your fast.
- Make a commitment. Sometimes it can help to get a friend or trusted family member to hold you to your fast commitment. It's harder to break a fast when someone is monitoring you.
- Log your fast. As you're preparing for your fast, write down each day what you eat, how you feel, and what your objective is. Do this during the fast, so that you see how your body changes and processes the change and to keep you focused on why you're doing this.
- Prepare yourself physically. This means following your doctor's advice and specifically following the pre-fast and fasting rules for your preferred fast. Deviating from these can make your fasting time much more difficult and uncomfortable.
3
Make sure you know the health concerns and benefits. Although there may be good health reasons for fasting, it is not a good weight-loss tool, because so often you simple gain the weight right back once you finish fasting and you can't add the healthy exercising as well.^{[9]
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- Some things to watch out for are heartburn (the stomach will produce more acid during a fast when you think about food, or smell food) so if you take medication for indigestion, you should continue to take it. You can also have trouble with dehydration during a fast, so make sure that you drink extra water and fluids. Constipation can be troublesome, as well, as you won't be exercising as regularly (or eating foods that help constipation).
- People who shouldn't fast are those with compromised immune systems, diabetes, kidney problems, who are pregnant, who have cardiac arrhythmia, and so on.

Warnings

If you have diabetes do NOT fast. Fasting can cause dangerous dips and spikes in your blood sugar levels.

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You really need to do a fast under the observation of a physician, especially if you're going to do a longer fast or you have health problems.

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Do NOT fast if you are only doing it to lose weight and for no other reasons

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