Is Fasting One Day a Week Good for Your Health?
By Dr. Ben Kim on June 13, 2008
Is fasting one day a week good for your health? To answer this question, let’s take a look at what happens in your body when you begin to eat and drink nothing but water.
After your cells use up the sugar that is in your bloodstream from your last meal or beverage, your body has to find another source of energy for your cells. And the first places that it turns to are your liver and your muscles. Both your liver and your muscles store sugar in the form of glycogen, and when needed, glycogen can be broken down to glucose, which all of your cells can use to produce energy for their ongoing activities.
During a water-only fast, your glycogen stores are depleted within about 24 hours, give or take a few hours. After your glycogen stores are used up, most of your cells begin burning fatty acids for energy – these fatty acids come from your fat reserves, including fatty tissue that surrounds your organs.
Two groups of cells – your red blood cells and your brain cells – cannot use fatty acids to fuel their energy needs. Your red blood cells and brain require glucose, and once glycogen/glucose from your muscles and liver are used up, your brain and your red blood cells get their glucose from two sources:
- From glycerol, which is a component of your fat tissues.
- From your muscles – some of your muscle tissues get broken down, and the amino acids from your muscle tissues are used to produce glucose for your brain and red blood cells.
Clearly, it’s not in your best interest to rapidly eat up your muscles to meet the energy requirements of your brain and red blood cells during a water-only fast. Your body knows this, and somewhere between the 2nd and 3rd day of water-only fasting, your liver begins churning out ketones, which during a water-only fast, come primarily from the breakdown of fatty acids from your fat reserves.
Once your liver generates large numbers of ketones, your brain is able to use ketones as fuel for itself. At this point, only your red blood cells require glucose that must still be derived from breakdown of your muscles, but with your brain no longer dependent on breakdown of your muscles for energy, the rate at which your muscles are catabolized will be such that your muscles are spared as much as possible – this state is called “protein sparing” – it’s a survival mechanism that is built into human physiology to deal with times of famine.
Getting back to the big picture, it should be clear that from about the 2nd or 3rd day of a water-only fast, your body meets it energy requirements by burning through your fat reserves.
Since the bulk of the toxins in your body are stored in your fat reserves, the longer you fast on water only, the more fat you’ll burn and the more toxins you’ll eliminate from your system.
This is why we see elimination of lipomas, atheromas (accumulated waste in your blood vessels), and other conditions related to toxin accumulation during a prolonged water fast.
Put another way, your body does not experience significant detoxification during the first 12-24 hours of a water-only fast.
Your body begins to eliminate large quantities of toxins only after it begins to burn your fat reserves at a rapid rate. And this doesn’t happen until you’ve used up the glycogen stores in your liver and muscles.
So when you fast one day a week, you deplete the stores of sugar in your liver and muscles, and you begin to break down your muscles – these are the main things you accomplish during the first day of water fasting. Significant detoxification only begins to occur if you continue past day one of fasting.
This is not to say that there are no benefits to fasting one day a week, or that you don’t eliminate any toxins during a one-day fast.
You are eliminating toxins with every breath that you take. And your body will always increase its rate of ongoing detoxification whenever you get more rest and/or eat less food, because less digestive burden and more physical rest always mean more available resources for detoxification.
Rather than fast one day a week on water only, I think it makes more sense to do a juice fast one day a week, or even once a month. With a juice fast, you can supply your body with enough nutrients that you don’t have to deplete the sugar stores in your liver and muscles, or break down a lot of your muscle tissue. At the same time, because the nutrients in freshly pressed juices are so easily digested, a one-day juice fast can ease digestive burden and enhance ongoing detoxification to some degree.
But let’s be clear: the main benefit of a one-day juice fast is not significant detoxificiation; it’s a concentrated period of rest for your digestive organs, and an opportunity for the organs that are responsible for ongoing detoxification (liver, kidneys, skin, and lungs) to do a little extra health-promoting work.
To sum things up, I would say that it’s not good for long term health to fast one day a week on water only. If you want to give your body a period of rest and intense cleansing once in a while, it makes more sense to spend a day eating all raw fruits and vegetables, or drinking nothing but freshly pressed juices. If experiencing this type of cleansing period is of interest to you, I recommend that you view the following series of articles:
Full Body Cleanse: The Basics
If you do a Google search for full body cleanse, your web browser will bring up more than 2 million Web sites that offer information on how to experience a full body cleanse. If cleansing and detoxifying for health purposes wasn’t a mainstream topic before, it certainly is now with the recent launch of Oprah’s 21-Day Cleanse.
Here are some of the most common questions that I receive on a weekly basis from people seeking guidance on how to cleanse and detoxify their bodies:
What’s the best way to detoxify my body?
How do I prepare for a cleanse?
How do I return to my everyday routine after a cleanse?
Is it okay to detox while I take my meds?
How do I cleanse my liver?
If you’re not quite sure what to make of the whole cleansing and detoxing craze, I hope that this three-part series on cleansing gives you a solid understanding of this important health topic.
What Exactly is Detoxification?
Detoxification refers to the process of eliminating toxins from your body.
There are two major types of toxins that your body accumulates over time:
Environmental Toxins: Sometimes called exogenous (made outside your body) toxins, environmental toxins include all the chemicals and pollutants that you’re exposed to through air, water, and food.
Common environmental toxins include pesticides, herbicides, prescription and over-the-counter medications, carbon monoxide, triclosan, bisphenol A, phthalates, and volatile organic compounds.
Metabolic Toxins: Sometimes called endogenous (made inside your body) toxins, metabolic toxins are produced by each of your cells as they go about their everyday metabolic processes. Metabolic toxins can also be produced by microorganisms that act on incompletely digested food in your digestive tract.
It’s normal for your cells to contain some toxins at all times. After all, your cells need to manufacture energy on an ongoing basis, and the manufacturing process results in waste (toxin) production.
Toxins only present a challenge to your health when they accumulate to a point where they interfere with cellular function – we call this state toxicosis.
The first effect of toxicosis is disruption of cellular function. If a group of cells experience significant toxicosis, specific health challenges develop, examples being thyroiditis, hepatitis, prostatitis, unexplained chronic fatigue, and problems with vision. If toxicosis persists, it’s possible for the DNA in your cells to become damaged, which may lead to abnormal cellular growth of the affected cells.
While the majority of chronic health challenges are caused by more than one factor, I hope that it’s clear that allowing your body to accumulate toxins over the long haul can result in you developing any one of the chronic diseases that are plaguing people in industrialized countries. To be clear, toxicosis cancontribute to coronary artery disease, high blood pressure, type 2 diabetes mellitus, respiratory illness, kidney disease, liver dysfunction, autoimmune illness, hormonal imbalances, skin conditions, and most types of cancer.
Your Body is Constantly Detoxifying and Cleansing
The good news is that your body is designed to constantly gather up and remove toxins from your cells. Most of the toxins that are stirred up from your cells are broken down in your liver, and then eliminated from your body via your kidneys, colon, skin, lungs, and mucus linings in your nose and ears.
Put another way, every time that you urinate, defecate, exhale, cough, sneeze, and experience an inside-out reaction with your skin, your body eliminates toxins from your system.
If your exposure to toxins rises, your body increases its output through the eliminative channels mentioned above. If your eliminative mechanisms cannot keep up with the number of toxins that are coming in and being generated in your cells, in an effort to preserve your health, your body attempts to store some of the toxins in your fat tissues. Even if you are lean for your body type, your body can store toxins in fat tissues that can be found interspersed between your muscle fibers and surrounding your organs.
The bottom line is this: Your body is committed to eliminating harmful toxins from your system at all times. Toxins can become problematic to your health if you accumulate enough of them to experience cellular dysfunction.
Full Body Cleanse
I hope that it’s clear that your body is experiencing a full body cleanse at all times. Put another way, your body is constantly at work to keep every cell in your body as healthy as possible.
Any effective full body cleanses or any other type of cleansing program that you go through should be designed to accelerate the detoxifying process that your body is already engaged in.
There’s not a lot that you have to do to encourage your body to rid itself of toxins.
You can accelerate cleansing and detox by reducing the number of exogenous and endogenous toxins that you are exposed to, and by giving your body the rest that it needs to devote its resources to its cleansing and detoxifying mechanisms.
Put another way, to experience a truly effective period of intense cleansing, you don’t need to give your body much by way of nutrients. Actually, all you need to give your body are physical and emotional rest, fresh air, water, and enough fuel to sustain your most basic metabolic processes. And as people who understand water fasting know, the fuel that you need for intense cleansing can actually come from reserves found in your liver, muscles, and fat.
But this isn’t an article about water fasting. This is an article about how to experience accelerated full body cleansing while going about most of your everyday routine.
Before we get into a specific protocol for intense cleansing, let’s address one final point: your body cleanses and detoxifies itself evenly. What I mean by this is that there’s no way for your body to cleanse your kidneys first, and then your liver, and then your eyes, and so on and so forth. Your body detoxifies all of its cells at about the same pace.
This doesn’t mean that every part of your body will feel healthier at the same pace, as each of your body parts has its own history and genetic predisposition. Let’s say, for example, that you have a long history of acne. If you begin a period of intense cleansing, it may be days or weeks or months after your internal organs have become significantly cleaner and healthier when you observe improvement in the health of your skin. And if other factors are contributing to your acne (such as an imbalance in your endocrine system), you may need years of healthful living to experience lasting improvement in skin health and tone.
Please don’t forget this fact: many chronic health challenges take years to develop, so it’s unrealistic to expect such challenges to fully heal within months, even if you fully support your cleansing mechanisms.
This last point is one that you probably won’t find on most of the more than 2 million Web sites that discuss how to experience a full body cleanse.
Although it may be disheartening to know, the truth is that lasting improvement in your health may take many months or years to manifest itself. You may feel better within days, but I hope that what you’re really shooting for is to build a foundation of health that will serve you for decades.
Also, please remember that the positive effects of an intense period of cleansing will last only as long as your dietary and lifestyle choices support your health after your cleanse. Your body is working its tail off to detoxify itself as you are reading these words, and it will continue to do so during an intense cleanse, and after an intense cleanse. Full body cleansing never stops – it is always happening at the pace that your daily choices allow. If you want to experience your best health, your job is to support your body’s self-cleansing mechanisms every day.
How to Experience an Intense, Full Body Cleanse
As mentioned earlier, here are the most basic requirements for an intense, fully body cleanse:
- Expose yourself to as much fresh air as possible.
- Get as much physical and emotional rest as possible.
- Stay hydrated with water-rich foods and liquids.
- Minimize your exposure to exogenous and endogenous toxins
Full Body Cleanse: Diet
During an intense, full body cleanse, the goal with your diet is simple: it’s to minimize the workload on your digestive organs while supplying your body with enough energy to carry out its everyday activities. Cleansing is performed primarily by your body’s self-regulated cleansing mechanisms, not by the nutrients in the foods that you eat.
Vegetables, fruits, and their juices are excellent food choices for an intense, full body cleanse for the following reasons:
- For most people, vegetables and fruits are extremely easy to digest.
- Vegetables and fruits are naturally rich in water; staying hydrated is an essential requirement for an intense, full body cleanse.
For the vast majority of people, grains, legumes, nuts, seeds, and all cooked animal foods are harder to digest than vegetables and fruits. So for an intense period of cleansing, it’s best to avoid everything but vegetables, fruits, their juices, and water.
How to Prepare for an Intense, Full Body Cleanse
Before beginning, it’s ideal to take a week or at least a few days to taper your intake of the following:
- Sugar and other sweeteners
- All animal foods, including dairy, eggs, fish, shellfish, chicken, beef, pork, and all other flesh meats
These foods put significant strain on your digestive organs, and avoiding them “cold turkey” can sometimes create withdrawal symptoms that are too powerful for some people to tolerate.
It’s fine to eat grains, legumes, nuts, and seeds right up until the day before you begin your intense period of detox – these foods are rich in fiber, and their remains should move through your digestive tract without too much difficulty during your intense cleanse.
If you don’t wish to spend up to a week to taper your intake of the foods listed above, it’s fine to begin right away; just be aware that you may experience highly uncomfortable symptoms of withdrawal, like strong headaches, lightheadedness, and nausea.
Other than tapering the foods-to-avoid during your cleanse, all that remains during the preparatory phase is to make sure that your kitchen is well stocked with vegetables and fruits that you enjoy.
Here is a list of vegetables and fruits that can be used for a highly effective cleanse:
- Dark green, leafy lettuce (romaine, red leaf, green leaf)
- Red beets (one or two will last a week)
- Bell peppers
- Yukon gold or new potatoes
- Sweet potatoes or yams
- Acorn or butternut squash
- Oranges and grapefruit
- Blueberries, raspberries, blackberries, goji berries, and any other berries that you enjoy
- Any other fruits or vegetables that you enjoy raw or juiced
Clearly, it’s best to choose fruits and vegetables that are in season. Organic varieties are best, but my experience has been that non-organic produce can also be used to experience an intense period of detox.
Regarding liquids: Have on hand plenty of water that you feel comfortable drinking. When weighed against all of the moment-to-moment dietary and lifestyle factors that affect your health, so long as your water isn’t intentionally poisoned, even municipal tap water can be used to experience a highly effective cleanse.
It’s fine to drink warm or hot water.
It’s also fine to use sparkling mineral water as you desire, although you should mainly drink “still” water during your cleanse.
Regarding medications: Please do not taper or stop taking prescription medications without your physician’s consent.
Regarding nutritional supplements: Avoid any supplements that contain synthetic nutrients, protein isolates, grains, nuts, seeds, or lecithin. It’s fine to take whole food supplements that contain nothing but vegetables and/or fruits. It’s also fine to take a probiotic as long as it doesn’t have added protein, grains, nuts, seeds, or lecithin.
Regarding equipment: If you can chew your foods well, you don’t need much by way of equipment. If you have access to a strong blender and a juicer, you can make smoothies and juices during your intense cleanse, but these aren’t absolutely necessary.
The Full Body Cleanse Diet
Eat any raw, ripe fruits that you desire, along with any combination of lettuce, celery, and avocado, if desired.
If you have trouble staying full on just raw fruits and vegetables, be sure to have avocado with your fruit, as the healthy fatty acids found in avocado should help you stay satisfied until your next meal.
If you’d like, you can blend up your morning meal into a smoothie.
You can also have water, sparkling water, or a hot drink made with boiling water and peppermint or chamomile tea.
Eat a large vegetable salad with as many different vegetables as possible. If you would like a salad dressing, use extra-virgin olive oil, fresh lemon juice, fresh orange juice, fresh lime juice or any combination of extra-virgin olive oil and citrus juice. Try to avoid vinegar, honey, salt, and spices.
If you have trouble feeling full, again, try to include an avocado with your salad.
If you don’t think you can make it to dinner on a raw vegetable salad with avocado, have a steamed Yukon gold potato, new potato, or sweet potato after your salad.
Feel free to have water, sparkling water, or peppermint or chamomile tea after your lunch meal. Also feel free to have any fresh, ripe fruits that you desire after your vegetable salad.
Eat any combination of raw vegetables and fruits that you desire, but aim to have at least as many vegetables as fruits.
If you’re still hungry after eating raw vegetables and fruits, have any steamed vegetables that you enjoy, such as steamed broccoli, cauliflower, cabbage, corn, and asparagus.
If you’re still hungry after eating steamed vegetables, feel free to have steamed root vegetables, such as steamed potatoes, sweet potatoes and carrots.
Have as much water, sparkling water, or peppermint or chamomile tea that you desire.
Any raw fruits, vegetables, their juices, and smoothies made with raw fruits and vegetables are fine snack choices. For a dip to eat with raw vegetables, have guacamole made with avocado, red onion, and lemon or lime juice.
Full Body Cleanse Sample Menu
Big bowl of watermelon with a large handful of romaine lettuce leaves and 1/4 to 1/2 of an avocado.
A large vegetable salad made with leafy lettuce, cucumber slices, tomato slices, shredded carrots, shredded red beets, sliced red onions, shredded zucchini, 1/2 to 1 whole avocado, 1/2 a sweet bell pepper, and raw corn kernels.
Optional: Dressing made by mixing one part extra-virgin olive oil and one part orange juice.
Small bowl of romaine lettuce, celery sticks, mango, and blueberries.
Steamed cabbage, broccoli, and 1/2 to 1 whole raw avocado.
Smoothie made with banana, blueberries, mango, and water.
Full Body Cleanse Schedule
A nice feature of this full body cleanse is that you can follow it for however many days you desire and/or your schedule allows.
Initially, you may want to try it over the weekend, beginning on Friday evening, and ending on Monday afternoon.
Many people find that seven full days is quite manageable, and produces noticeable changes in energy level and sense of well-being. The first while can be tough for some people who experience severe symptoms of withdrawal, but for the majority of people who experience such symptoms, things start to look up after a few days.
If you like how this program of eating makes you feel, it’s fine to continue with it for as long as you feel strong and healthy.
When you’re ready to add other foods back into your diet, it’s best to proceed slowly. On the first day of “breaking” your cleanse, you should follow the same diet, but add one additional food to your afternoon or evening meal, like hummus made with chickpeas.
On day 2, you can have two servings of protein-dense foods; say a serving of eggs with lunch and a serving of fish for dinner.
As you break into a long-term pattern of eating, the goal should be to keep the full body cleanse diet as the foundation of your diet, and to add small servings of healthy, protein-dense foods (grains, legumes, nuts, seeds, and animal foods) to your meals as your appetite dictates.
How to Use Fresh Juices during Your Full Body Cleanse
After a day or two of getting right into the full body cleanse diet, it’s fine to try a day or two of having nothing but fresh juices.
Because juices are mostly devoid of fiber, they put even less burden on your digestive organs than the whole foods that they come from. Less digestive burden translates to more energy being available for your self-regulated cleansing mechanisms.
Here are some guidelines for juicing days:
- Have as many freshly pressed juices as you desire.
- Stick mainly with green juices that are made with a foundation of dark green, leafy lettuce and celery. Use only small amounts of sweet root vegetables like carrots and red beets.
- If you want to have some freshly pressed fruit juice, mix it 50/50 with a non-sweet vegetable juice.
Here’s an example of what a juicing day might look like:
6 leaves romaine lettuce
2 ribs celery
6 leaves green leafy lettuce
6 leaves romaine lettuce juice
2 leaves green cabbage
Big handful of kale or Swiss chard
2 ribs celery
3 ribs celery
Squeeze of lemon juice
After your juicing day(s), go back to the full body cleanse diet described above for at least a day before adding protein-dense foods to your diet.
An alternative to doing full juicing days is to substitute one of your regular meals with a freshly pressed vegetable juice.