Dry Fasting Is A Version Of Intermittent Fasting That Restricts Liquids, And Yup, That Includes Water
If you're familiar with the intermittent fasting (IF) diet (which is a celeb favorite, btw) you probably know that it involves eating during certain time periods and fasting during others, depending on the IF schedule you're following. It might sound tough to go, say, 16 hours without any food, but luckily, many fasting periods include the time you're sleeping or early in the day or late at night when you might not be so hungry anyway.
And, even though you're not eating solid foods, most fasting plans allow you to have low- or zero- calorie beverages while you fast, like water, coffee, and tea. That is, unless you're following the super strict, kind of buzzy version called dry fasting, which also involves the elimination of *all* beverages for extended periods of time.
Many people do dry fasting at times for religious reasons. But the diet has picked up traction as a method for weight loss (!). If that sounds bonkers to you, you're not alone. Here's what you need to know about it—and how safe it really is.
Okay, so what exactly is dry fasting?
Some people exclude all foods and beverages for an extended period of time every day during religious practices like Ramadan. For example, when it comes to dry fasting for Ramadan, people who partake do their dry fast from sunrise until sunset every day for a month. For the purpose of this article, we will cover dry fasting in a health and weight loss context.
Again, when people choose to following a fasting diet for health reasons, they typically still allow certain liquids like coffee and water, and in the case of a juice fast, juice. Dry fasting, on the other hand, involves the restriction of both food and liquids for a large portion of your day, and sometimes up to 24 hours or longer, says Joel Totoro, RD, a sports dietitian and director of sports science at Thorne Research in Scottsdale, Arizona.
How do you do a dry fast?
Many people do dry fasts as a sort of reset to their diet. The fasting can vary in length, but this kind of eating pattern isn't an every day thing—it's usually done for a certain amount of days before returning to a more sustainable eating style.
During dry fasting, some people choose to get their fluids by loading up on fruits and vegetables when they’re in an eating period, but this isn’t an effective way to meet overall hydration needs, says Totoro, especially if you're physically active regularly.
What are the purported benefits of dry fasting?
Fans of intermittent fasting have made plenty of claims about its health benefits, but more research is still needed to solidly a lot of these statements. This is what the current research says about how fasting in general (not only sans water) may help your body and mind.
1. Weight loss
Any sort of fasting can support calorie restriction, which may lead to weight loss. In a 2013 study in the Journal of Human Nutrition and Dietetics, scientists analyzed the effects of dry fasting during Ramadan. The research included 240 healthy adults who dry-fasted for at least 20 days. A week before the holiday, researchers measured the participants’ body weight and calculated their body mass index (BMI). A week after Ramadan ended, the researchers took the same measurements, and found that body weight and BMI was lower in almost everyone who took part in the study.
Of course, just because dry fasting results in short-term weight loss doesn't mean it's healthy or the most sustainable method for losing weight. Research has not shown dry fasting to be any more beneficial than other intermittent fasting diets that allow for fluids such as water, tea, and coffee, says Totoro.
2. Improved insulin sensitivity
New Jersey-based dietitian Erin Palinski-Wade, RD, author of 2 Day Diabetes Diet, says that in some studies intermittent fasting has been found to reduce blood sugar levels and reduce insulin resistance, which can be very beneficial to those at risk of developing type 2 diabetes.
The results of a 2018 study published in Cell Metabolism are notable here: Researchers found that even without weight loss, early time-restricted fasting increased insulin sensitivity in men with prediabetes. (Most other similar studies can’t definitively say whether insulin sensitivity improves because of the fasting schedule itself, or because most people lose weight when they fast, which also improves insulin sensitivity.)
3. Better concentration
Palinski-Wade notes that some animal studies have shown intermittent fasting to be protective to the brain by improving its function and structure, like in this 2018 study in Experimental Biology and Medicine, which suggests fasting may protect against Alzheimer’s disease by reducing the incidence of memory loss.
Obviously, more research is needed to see if this is also true in humans—but at some point in the future, those results may apply more broadly.
4. Reduced inflammation
At the root of many of fasting’s health benefits is a reduction in inflammation, and that’s a connection being studied pretty closely by experts interested in the relationship between fasting and overall health.
In 2019, researchers at Mount Sinai found that intermittent-fasting cycles lasting less than 24 hours reduced the number of pro-inflammatory monocytes in the blood. High levels of monocytes have been associated with some chronic inflammatory and autoimmune diseases.
Similarly, the Yale School of Medicine studied the effects of fasting and diets on the body’s macrophages, or inflammatory immune cells, and found that low-carb dieting, fasting, or high-intensity exercise may help to reduce that kind of inflammatory response.
5. Stronger immunity
In the last two years, proponents of fasting have claimed that restricting caloric intake for even a short period of time can “reset” your immune system, giving it a much needed power boost.
This theory was born out of a University of Southern California study on both mice and humans, which suggested that fasting for 72 hours could allow your body to flush out damaged immune cells and regenerate new, healthier cells primed to help the body fight toxins. (The effects of fasting on patients undergoing chemotherapy were examined in this particular study.) Still, more research is needed to know for sure if fasting is really a boon for immunity.
6. Delayed aging
A 2019 study in Cell Metabolism found that alternate day fasting, specifically, improved some of the more common markers of aging—like cardio health and fat-to-lean ratio—in a small sample of healthy, non-obese people.
Elsewhere, the National Institute on Aging has reported that male mice that ate less frequent meals lived longer compared to mice that ate more frequently, with fewer liver diseases and metabolic disorders.
But dry fasting in particular sounds pretty extreme. Is it safe?
Fasting can be different for everyone and some people have better experiences with it than others, depending on their previous diet, fitness level, and individual health, says Emmie Satrazemis, RD, CSSD, a sports dietitian and nutrition director at Trifecta Nutrition in Sacramento, California. But, tbh, many health experts wouldn’t recommend you try a dry fast, especially if you have any pre-existing medical conditions or a history with eating disorders.
These are the potential side effects of dry fasting:
Increased hunger and thirst
Dehydration
Headaches
Gastrointestinal distress
Mood swings
Fatigue
Picking up disordered eating habits
“Since your body can only survive an average of three days without water, it is not recommended to dry fast for an extended period of time or more than a 24-hour window," Satrazemis says. If you’re exercising, abstaining from fluids can be especially dangerous and put you at risk for dehydration and heat stroke in warm weather.
“Any feelings of dizziness, fainting, rapid heart rate, or dark urine are all warning signs to look out for that would indicate you are putting your body at risk,” says Totoro. (Yikes.) If you are experiencing any of these symptoms, end your dry fast immediately, eat food, and drink water—and call your doctor if your symptoms don't improve.
The bottom line: From a health standpoint, the best way to achieve sustainable weight loss is to focus on a well-rounded diet and exercise. At the end of the day, the risks of dry fasting can far outweigh any potential benefits.
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