Intermittent fasting is when you periodically abstain from food. Dry fasting is when you abstain from food, water, and any other liquid. How long you go without food and liquids depends upon your fasting schedule. There are scientifically proven dry fasting benefits, but it’s not for everyone. We’ll cover what you need to know before you begin dry fasting. But first, a little history.
A History of Dry Fasting
Humans have been dry and intermittent fasting since we began walking the earth. We used to hunt and gather our food and water, and we could go days or weeks without finding what we needed. So fasting was a natural part of life.
Today, many cultures fast as part of their spiritual practice. For thousands of years, devout Muslims have practiced dry fasts during the month of Ramadan, which gives us a population in which to observe the effects of dry fasting.
During the ninth month of the Muslim calendar, those practicing Ramadan abstain from all food and water during daylight hours, only breaking their fast after sundown. Depending upon one’s geographical latitude, this type of intermittent fasting mimics a 16:8 fast, 20:4 fast, or more.
The Jewish tradition of Yom Kippur is traditionally a dry fast of more or less than 24 hours, from sundown the day before Yom Kippur, to one hour after sunset on a holy day. In some cases, all contact with water is avoided, including for bathing or recreation.
These types of fasts are done for spiritual purposes. They offer a ritual cleansing and atonement, self-awareness, the practice of self-discipline, and the opportunity to get closer to one’s God. By highlighting the desire for food, fasting rituals draw attention to the all-pervasive underlying desire, the longing to be closer to one’s deity.
What Science Says About Dry Fasting
Science supports what ancient religions say about fasting for cleansing or purification. Scientists who studied dry fasting observed short-term antioxidation, immune system stimulation, and reduced inflammation in participants that abstained from both food and water.
Closer to God, or closer to calm? A 2006 study of both fasting and non-fasting Muslims in Indonesia demonstrated that those who participated in Ramadan fasts experienced decreased blood pressure by the third week of the month-long holiday.
Another study completed in 2006 found that the body mass index of both men and women decreased over the 30 days of Ramadan. Total cholesterol remained unchanged, glucose and high-density lipoprotein (HDL-C) decreased, and low-density lipoprotein (LDL-C) increased.
In 2012, a team studying the impact of Ramadan Intermittent Fasting (RIF) on selected inflammatory cytokines and immune biomarkers found reduced inflammatory markers (RIF) in healthy subjects. Body fat and overall inflammation were reduced by the third week of Ramadan, and the changes lasted for up to one month.
A 2020 study concluded that dry fasting offers “short-term antioxidant, anti-ischemic, immune-stimulating, anti-edematous, and anti-inflammatory effects.” In other words, dry fasting can potentially boost immunity, decrease inflammation, decrease edema and fluid retention, and reduce ischemia – a restriction of the blood vessels.
While millions of Muslims dry fast each year for Ramadan, science has yet to connect the negative water balance incurred during this time with any detrimental effects. Hypohydration, or the chronic state of dehydration, is avoided with the post-sundown meal that takes place at the end of each day.
A 2003 review of Ramadan-fasting studies to date found that few health problems can be attributed to dry fasting, while several positive metabolic changes occur.
Benefits of Dry Fasting
The benefits of intermittent fasting are numerous. Intermittent fasting has proven effective for fat reduction (weight loss) while preserving muscle mass. Intermittent fasting can decrease blood sugar and increase insulin sensitivity. Intermittent fasting can improve brain health and reduce the signs of aging. The benefits of dry fasting are the same as intermittent fasting, and forgoing water may even increase them.
Increased Anti-inflammatory Effects
Systemic inflammation taxes your body’s immune system and has adverse effects on your joints, organs, and arteries. So, any reduction in inflammation is beneficial. Research shows dry fasting offers the following anti-inflammatory benefits:
- Increase in cortisol, a hormone that reduces inflammation
- Increase in adrenocorticotropic hormone (ACTH), which stimulates the release of cortisol
- Elevated total antioxidant capacity (TAC) in plasma
- Increase in erythrocytes, or red blood cells, which play a role in scavenging inflammatory agents
- Increase in hematocrit, which measures the presence of red blood cells
- Increase in noradrenaline, which reduces inflammation
- A decrease in adrenaline, a pro-inflammatory hormone
Improved Blood Lipid Profile
According to a 2006 study of fasting during Ramadan, dry fasting may improve several essential biomarkers of health found in the blood. Additional studies in 1997 and 2012 agree with the 2006 findings which show intermittent dry fasting can:
- Increase in HDL-C (the “good” cholesterol)
- Reduce LDL-C (the “bad” cholesterol)
- A decrease in total cholesterol (not seen in the 2012 study)
- Lower triglycerides, which contribute to hardening of arteries
- Offer lasting results for up to 4 weeks after dry fasting had ended
Studies concluded RIF could reduce cardiovascular heart disease risk for both healthy and hyperlipidaemic subjects.
Lower Blood Glucose
Intermittent fasting decreases your blood glucose levels and increases your sensitivity to insulin. Likewise, dry fasting is shown to reduce blood glucose levels in participants and appears to improve blood glucose control in those with diabetes.
Increased Fat Reduction
Dry fasting may improve your ability to lose fat. When your body isn’t getting water, your body uses your fat stores to create it, which results in fat loss.
Studies show that fat is a particularly good source of metabolic water supply, as 100 grams of fat can yield up to 110 grams of metabolic water. In comparison, 100 grams of carbohydrates would only yield at best 55 grams of metabolic water.
It may be beneficial to eat high-fat foods or temporarily follow a ketogenic diet to increase your fat-burning through this process. One study found those who ate a high-fat meal before dry fasting experienced the least discomfort, hunger, and thirst during their fast.
Types of Dry Fasting
As with intermittent fasting, dry fasting offers various protocols to choose from depending on your experience with fasting, current health conditions, and goals.
Intermittent Dry Fasting
Intermittent dry fasting is when dry fasting is done periodically. Your body gets a chance to rehydrate and refuel within each 24-hour period, which makes this the safest form of dry fasting.
Ramadan intermittent fasting is a perfect example, since fasting typically lasts for 12-16 hours each day, as measured from sunrise to sundown. Usually, a RIF fasting plan takes place for 28-30 days.
Like intermittent fasting, Intermittent dry fasting is measured hourly. Protocols include the popular 16:8 in which you fast for 16 hours, then eat and drink regularly for the remaining 8 hours.
The Eat Stop Eat method is similar in that you’ll eat at least one full meal per day, which makes a dry fasting variation of this plan relatively safe for short periods.
Prolonged Dry Fasting
When you fast for 24 hours or more, it’s generally referred to as an extended fast. But, don’t try this if you’re dry fasting. If you go more than 24 hours without liquids, it can be dangerous.
Even in the most extreme cases, where latitude keeps the days long and the nights short, Ramadan fasts rarely exceed 24 hours. While humans can go without food for up to three weeks and survive, rarely can the human body go beyond 48 hours without water.
If you enjoy prolonged intermittent fasting protocols such as alternate day fasting, it’s safest to do a “wet fast.” So, drink water and stay hydrated while you’re on these types of plans.
Absolute Dry Fasting
Typically practiced in a religious context, absolute dry fasting is when you abstain from all contact with water during the fast, which means no showers, swimming, or bathing. Research shows no metabolic benefit to this type of fasting.
Metabolic Adaptations to Dry Fasting
In the absence of food or water, your body turns to its reserves of glycogen for fuel. Glycogen typically gets depleted anywhere from 12-72 hours. When that happens, your body uses fat stores as a source of fuel.
This metabolic shift often referred to in terms of dry fasting stages, spurs ketosis. Ketosis increases fat burning, especially in the abdominal area, benefits the brain, and may even prevent or mitigate Alzheimer’s disease.
Metabolic shifting occurs, however, with “wet” intermittent fasting too, and there’s insufficient evidence to suggest that dry fasting will cause this metabolic shift to happen sooner.
It can be helpful if you’re adapted to use fat as a source of fuel. Ketosis may occur sooner if you already eat a low carbohydrate or ketogenic diet.
Is Dry Fasting Safe?
Dry fasting is safe as long as you follow the instructions and listen to your body. When you go without water for an extended period, you may be at risk for dehydration. It’s always best to be safe, so drink water if you have any doubts about your hydration level. Chronic dehydration or hypohydration is highly correlated with obesity, diabetes, heart disease, and high blood pressure. You must rehydrate adequately during your eating window when you dry fast.
Milder but uncomfortable side effects of intermittent dry fasting include the following:
Your body may have difficulty differentiating between hunger and thirst, and your appetite can increase if you’re dehydrated.
Tiredness & Irritability
When you’re hungry, you might feel irritable and lack energy. Dehydration may also make you feel tired, and it won’t improve your mood.
Headaches & Brain Fog
You may experience dehydration headaches when your body doesn’t have adequate fluids. Headaches can also arise if you typically drink caffeine and have eliminated it during your dry fast. Water accounts for 75-percent of your brain mass, so it makes sense that dehydration affects your cognitive performance.
Is Dry Fasting for Me?
Try dry fasting if you’ve successfully done intermittent fasting in the past with limited side effects. Use caution if you’re prone to headaches or migraines, and be sure you aren’t dependent on caffeine. You should avoid extreme physical exertion and excessive heat while dry fasting to prevent dehydration.
Dry fasting might exacerbate glaucoma, tear dysfunction, or cataracts, so if you have any of these eye conditions, it’s best to avoid dry fasting. If you suffer from kidney dysfunction, fasting may be contraindicated since it can make you prone to dehydration, kidney stones, and other health issues. Don’t participate in dry fasting if you take medications that depend upon food or water for delivery.
Also, if you’re pregnant, prone to eating disorders, or have had issues with eating disorders in the past, fasting isn’t recommended.
If you’d like to experiment with a dry fast, begin with a 14:10 or another mild protocol of intermittent dry fast to allow for sufficient daily hydration. But, listen to your body and be willing to break the fast or drink some water if needed.