Eat Empowered

What Is Dry Fasting—And Is It Safe?


It seems like nearly everyone has either heard about intermittent fasting from a friend or family member who’s dabbled in it—or perhaps even tried it themselves. For the uninitiated, intermittent fasting is an eating strategy that follows the clock; eat during a set window (typically 8 hours per day), then abstain from food during the other hours. 

While intermittent fasting does have some scientifically-proven health benefits, we’ve been pretty clear about the fact that there are only certain populations who should even consider trying it. And all of those benefits only last for as long as you can stick with it, which is often difficult to do for the long haul. (Ahem, no bedtime snacks…ever? No thanks.)

Even harder to stick with: A buzzy format of intermittent fasting that’s currently rising in popularity, dry fasting. So what is dry fasting, why are people so jazzed about it and most importantly, is it safe? Read on for all those answers and more, as we dish about the science of dry fasting.

What Is Dry Fasting, Exactly?

Dry fasting is a form of intermittent fasting in which no liquid is consumed during the fasting window., Dry fasting is modeled after certain religious fasts. During Ramadan, Muslims abstain from food and drink from dawn to dusk for 30 days, and for Yom Kippur, Jews dry fast from sundown to one hour after sunset on the holy day of Yom Kippur.

Dry fasting can be partnered with any of the common intermittent fasting methods below. So think of dry fasting as a subgroup of intermittent fasting. Similar to those aforementioned religious fasts, during the non-feeding times, those who “dry fast” don’t consume any fluids during the fasting window.  (Generally, non-calorie beverages such as water, coffee and tea are allowed during the fasting window on non-dry intermittent fasts.)

  • Time-restricted fasting: Eat normally for 8 hours of the day, such as between 11 a.m. and 7 p.m., then abstain from all food and drink for the other 16 hours.
  • 5:2 fasting: Eat normally for 5 days per week, then fast (by consuming 500 calories or less per day) for 2 days per week. 
  • Alternate-day fasting: Eat normally one day, then abstain from all food and drink on the next day OR consume 500 calories or less the next day.

RELATED: 5 Super Nutritious Foods You Really Should Be Eating (But Probably Aren’t) 

The Reported Benefits of Dry Fasting

The majority of studies about the benefits of dry fasting have focused on individuals participating in Ramadan. That means, these people eat and hydrate normally for 11 months of the year, so long-term benefits of dry fasting are difficult to pin down. For religious populations, dry fasting is meant to create deeper faith, more community (since the collective group is in it together) and a heightened sense of gratitude. For the rest of the population who participates in dry fasting as part of their intermittent fasting, they’re generally seeking weight loss. 

As you study up on the research about dry fasting benefits, know that most studies are fairly short-term and small in size.

Weight Loss

Intermittent dry fasting may lead to short-term weight loss, according to one study in the Journal of Human Nutrition and Dietetics. Take this with a grain of salt, however, as the weight loss is likely almost all water weight.

Improved Immune Function and Skin

Autophagy is the cellular anti-aging process that intermittent fasters are trying to take advantage of. By fasting for extended periods, the body uses the fasting window to “clean out” damaged and old cells to allow space to regenerate newer and healthier cells, which may enhance immune system defenses and potentially slow aging. (Take note that drinking enough water is one of the most essential habits for healthy, glowing skin over the lifespan.)

Less Inflammation

During about the third week of a dry fast, participants in a small study published in the journal Nutrition Research began to experience less chronic inflammation. That type of long-term inflammation is a contributor to many of the most common diseases in the U.S, including heart disease, diabetes, arthritis and allergies. Chances are this has much more to do with the eating change rather than skipping water, though.

RELATED: 5 Scary Things Inflammation Does to Your Body 

The Risks and Side Effects of Dry Fasting

As with intermittent fasting, those who dry fast often feel hungry (naturally). Dry fasters also may feel thirsty, irritable and tired, and may experience headaches, nausea, sleep troubles, dry mouth and eyes, dizziness and dark and/or infrequent urination.

In addition, here are some other very real medical risks of dry fasting.


About 60 to 70 percent of the human body is made up of water, and every part of that body requires water to function well. Potential complications of serious dehydration include seizures, heat exhaustion or heat stroke, brain swelling, kidney failure, shock caused by low blood volume, coma and even death.

Mental Fog

In a study published in the International Journal of Environmental Research and Public Health designed to determine how dehydration impacts mood, scientists discovered that those who didn’t drink water for 36 hours experienced not only shorter attention spans, but also delayed reaction time, short-term memory loss and fatigue.

Kidney Stones

Kidney stones form more easily within the body when the body is short in water to prevent kidney stone-creating crystals from clumping together into a painful mass.

Urinary tract infections

Water is crucial to flush out the germs that hang out in the urinary tract.

While intermittent fasting can work for some people who crave structure (ahem, if he or she can fill all nutrient needs within the eating window…and stick with it), dry fasting is a risky prospect. Instead, we recommend listening to your gut—literally. 

  • Eat when you’re hungry, not when the clock says you “can.” 
  • Fuel up with fruits, vegetables, lean protein, healthy fats and whole grains. Aim to pack each plate with a variety of colors. 
  • Wash it all down with plenty of H2O. Your body requires water for many basic functions and for satiety.

For more totally-doable diet advice, check out how to start eating healthy, according to a dietitian.

photo credit: shutterstock

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