Dry fasting involves restricting both solid foods and liquids, including water. While fasting in general may offer some health benefits, dry fasting can lead to dehydration and other potentially serious complications.

Fasting is when you willingly avoid food intake. It’s been practiced by religious groups around the world for thousands of years. These days, however, fasting has become a popular way to lose weight.

Dry fasting, or absolute fasting, restricts both food and liquid. It doesn’t allow any fluids, including water, broth, and tea. This is different from most fasts, which encourage water intake.

There are many ways to fast. Dry fasting can be done with any method, including:

  • Intermittent fasting. Intermittent fasting cycles between fasting and eating. Many people do the 16/8 method, which restricts food intake for 16 hours and allows eating during an 8-hour window.
  • Alternate day fasting. Alternate day fasting is done every other day. It’s a form of 1-day fasting.
  • Eat-stop-eat. In this method, you fast for 24 hours once or twice a week.
  • Periodic fasting. Food intake is restricted for set number of days, such as a 3-day fast once a month.

In general, there’s some evidence that fasting has benefits like weight loss and slower aging.

But dry fasting can be dangerous. Since you’re not allowed to drink water, you run the risk for dehydration and other complications.

There also isn’t enough research on the benefits of dry fasting. In this article, we’ll explore the supposed benefits, along with the potential side effects and dangers of the practice.

Fans of dry fasting say they’ve experienced the following benefits. Let’s explore the science behind each claim.

Weight loss

According to supporters, dry fasting is effective for weight loss. This is likely related to the extreme restriction of calories.

There’s some research on dry fasting and weight loss. In a 2013 study in the Journal of Human Nutrition and Dietetics, scientists analyzed the effects of fasting during Ramadan, a month-long Muslim holiday. People who fast during Ramadan don’t eat or drink from sunrise to sunset for one month.

The study included 240 healthy adults who fasted for at least 20 days. A week before Ramadan, the researchers measured the participants’ body weight and calculated their body mass index (BMI).

A week after Ramadan ended, the researchers took the same measurements. They found that body weight and BMI dropped in almost all the participants.

While the participants dry fasted, it’s important to note that it was done intermittently. Also, Ramadan fasting is only limited to one month, so it’s not continuous. It’s also only done by healthy adults.

These findings suggest intermittent dry fasting leads to short-term weight loss. Otherwise, there isn’t enough scientific evidence to confirm that repeated, regular dry fasting is safe or effective.

Improved immune function

People say dry fasting strengthens the body’s immune system. The idea is that fasting “resets” the immune system by removing damaged cells, allowing the body to regenerate new ones.

Additionally, there’s evidence that limiting calories (but not water) improves inflammation, which protects the immune system. It’s thought that complete calorie restriction has similar results.

Cell regeneration

In terms of cell regeneration, a 2014 animal study in Cell Stem Cell found that prolonged fasting triggers cell regeneration in mice. In a phase I human trial, the same researchers observed similar effects in people with cancer who are receiving chemotherapy.

However, the human study is in its early stages, and the article didn’t state if water was allowed. Studies are needed to determine if the same effects occur in healthy humans while dry fasting.

Reduced inflammation

The link between dry fasting and reduced inflammation has also been examined. In a 2012 study in Nutrition Research, scientists measured the proinflammatory cytokines of 50 healthy adults one week before Ramadan. This was repeated during the third week and one month after they dry fasted for Ramadan.

The participants’ proinflammatory cytokines were lowest during the third week of dry fasting. This suggests reduced inflammation while fasting, which may improve the immune system. But again, Ramadan fasting isn’t continuous, and water is allowed at certain times.

The link between dry fasting and improved immune function needs further research.

Skin benefits

Though water intake promotes healthy skin, it’s thought that dry fasting can help. This might have to do with the purported effects of fasting on the immune system.

Some claim fasting supports wound healing. According to a 2019 review in Nutrients, the increased immune activity due to fasting helps wound healing. A 2011 animal study in Wounds also found that temporary, repeated fasting sped up wound healing in mice.

Conflicting results are also present. In a 2012 animal study in Age, researchers found that calorie restriction slowed down wound healing in rats.

Other people think fasting slows down age-related changes, including skin aging. This is likely because calorie restriction is associated with slower aging. According to a small 2018 study in Cell Metabolism, calorie restriction reduced biomarkers of aging in 53 young, healthy adults.

Despite these findings, research hasn’t found specific skin benefits of dry fasting. Most research also involved mice. More studies are needed to confirm that fasting without water can help human skin.

Spiritual benefits

It’s said that dry fasting also enhances spirituality, which may be related to the practice of religious fasting.

Supporters have reported several spiritual benefits, including:

  • increased gratitude
  • deeper faith
  • improved awareness
  • opportunity for prayer

Allegedly, both religious and nonreligious people have reported experiencing spiritual benefits after dry fasting.

Faster overall results

People claim the benefits of fasting develop with regular, repeated sessions. But it’s believed that dry fasting delivers the quickest results because it’s the most extreme.

This is theoretical. To date, studies have only compared the effects of intermittent dry fasting during Ramadan with other types of fasting. An example is a 2019 review in Eastern Mediterranean Health Journal, where scientists found that these fasts produce similar results.

But researchers haven’t compared the rate of these results in the same experiment. Additional studies are needed to determine what type of fast yields the quickest, safest results.

Like all types of fasting, dry fasting has potential side effects. You might experience:

  • Persistent hunger. Hunger is a common side effect of any fast. Avoiding water can make you feel even hungrier, since water helps increase satiety.
  • Tiredness. If you don’t eat food or drink water, your body won’t have enough fuel. You’ll likely feel fatigued, dizzy, and weak.
  • Irritability. As the hunger builds up, you’re bound to feel cranky.
  • Headaches. Restricting caffeine and nutrients, especially carbohydrates, can lead to headaches.
  • Poor focus. When you’re tired and hungry, it can be difficult to concentrate at school or work.
  • Decreased urination. Omitting fluid intake will make you urinate less. If you become dehydrated, your urine may be dark and smelly.

If dry fasting is continued or repeated, serious complications can occur. These include:

  • Dehydration. Prolonged dry fasting can cause dehydration. This may result in electrolyte imbalances and low blood pressure, which can be life threatening.
  • Urinary and kidney problems. Dehydration can result in urinary tract infections and kidney stones.
  • Nutrient deficiencies. Vitamin and mineral deficiencies are associated with continuous fasting.
  • Fainting. Dehydration and hypoglycemia increase your risk of fainting.
  • Disordered eating. Some individuals may be more likely to binge eat after fasting, which increases the risk for disordered eating.

Dry fasting affects different people in different ways. So far, there isn’t specific research on how long it takes to see results.

It will depend on many factors, including:

  • overall health
  • age
  • daily activity level
  • how often you fast

To understand how other types of fasting work, consider the research, such as in this 2015 review in Molecular and Cellular Endocrinology and a 2012 study in Journal of Public Health. Remember that your results may vary.

While fasting has some benefits, there are other ways to lose weight, if that’s your goal. These methods are more likely to produce lasting results without the risk of complications.

  • Eat healthy. Eat a diet high in fruits, vegetables, and lean protein. Replace refined grains with whole grains and avoid added sugars to promote weight loss without omitting essential nutrients.
  • Drink water. Staying hydrated controls hunger and supports your body’s basic functions.
  • Exercise regularly. The best exercise program for weight loss includes both cardio and weightlifting. Cardio burns more calories each session, while weightlifting builds muscle, increasing caloric burn at rest.

Dry fasting is when you avoid food and liquid. Supporters say it helps weight loss and immunity, but there isn’t solid evidence to back these claims.

Most importantly, dry fasting can be very dangerous. It can lead to dehydration and other complications, especially if it’s repeated.

There are healthier, safer ways to fast or lose weight. If you’re interested in fasting, talk to your doctor first.