Dirty Fasting: Effectiveness, Recommendation, and More (2024)

Intermittent fasting is a popular practice that involves regularly engaging in periods of fasting, or not consuming calories, and a few types exist.

Alternate-day fasting refers to when you consume calories every other day. Also, time-restricted feeding — when you consume calories within a specific period or “feeding window,” typically lasts 6–10 hours and has grown in popularity in the last decade (1, 2).

Dirty fasting is a new practice being used by some people who engage in intermittent fasting.

This article explains what dirty fasting is, how it works, and whether it’s effective.

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Before diving into what dirty fasting is, it’s important to note that the term isn’t used in the medical community. There’s no research on this practice or how it compares with “clean” fasting.

Dirty fasting is a term used to describe consuming some calories during a fasting window.

This differs from traditional fasting or “clean” fasting, which restricts all foods and calorie-containing beverages.

People who practice dirty fasting will typically consume up to 100 calories during their fasting window. This may include some milk and sweetener in their coffee or a cup of bone broth.

Again, there’s no set definition of dirty fasting, so some people may consume many more calories during a dirty fast, while others may consume fewer.

On the other hand, people who practice traditional methods of fasting, or “clean” fasting, don’t consume any calories during fasting windows.

An exception to this is modified alternate-day fasting, in which you consume a small number of calories, typically 500 or so, on “fasting” days (3).

Advocates of dirty fasting suggest that having a small number of calories doesn’t technically “break” a fast and that this method of fasting makes it easier to maintain a fasting regimen.

Summary

Dirty fasting is a term for consuming a small number of calories during a fasting window. This differs from traditional or “clean” fasting, a method in which you don’t consume any calories during fasting windows.

Dirty fasting is technically modified fasting, meaning that you consume a small number of calories during fasting windows.

Although you’re still consuming some calories, any sort of calorie restriction will result in health benefits.

For example, if weight loss is your goal, dirty fasting can promote fat loss. This is simply because you’re likely consuming far fewer calories when dirty fasting than you would during a typical day of eating without time restrictions.

However, some people use intermittent fasting for the other benefits that fasting offers, including promoting autophagy, reducing insulin resistance and blood sugar levels, and more (4, 5).

Autophagy is a process that involves the programmed “cleaning” of cells. It’s an important process that’s necessary for maintaining healthy cellular function and preventing disease.

There’s no evidence that dirty fasting is as effective as traditional fasting methods — which involve complete calorie restriction during fasting periods — for promoting these potential benefits.

While consuming a splash of milk in coffee or a cup of bone broth isn’t the same as having a full meal, technically, you’re not fasting if you’re taking in calories, no matter whether it’s a small number.

Most experts agree that although taking in zero calories is the only way a person can be sure they’re truly in a fasted state, zero-calorie beverages like black coffee aren’t likely to break a fast.

However, drinking coffee with cream, milk, sweetener, or other calorie-containing beverages may break a fast.

Modified alternate-day fasting, which involves calorie intake during fasting windows, has been linked to some health benefits, including weight loss and reduced inflammatory markers, blood pressure, and cholesterol.

However, this practice is different than other types of intermittent fasting, which include complete calorie restriction during fasting periods (6).

This means that it may not have the same effects as traditional fasting methods that involve zero calorie intake during fasting periods. Similarly, dirty fasting should be considered a modified type of fasting.

Again, there’s no research specifically on dirty fasting. It’s likely that people who practice dirty fasting may not technically be in a fasted state during fasting windows, especially if they’re consuming more calories than they realize.

Summary

Dirty fasting is technically a modified type of fasting. The only way to ensure you’re in a fasted state is to abstain from all calories during a fasting window. For this reason, dirty fasting may not have the same effects as “clean” fasting.

If you’re interested in intermittent fasting, it’s best to choose a method that has research backing its effectiveness over dirty fasting, such as time-restricted eating — where you consume all of your calories within a specific timeframe (7).

For example, some people may choose to eat within a 6- or 8-hour window and fast for the remaining 16–18 hours.

The only way to ensure that you’re in a fasted state is to take in zero calories during your fasting window. However, most experts agree that the negligible number of calories in drinks like black coffee and herbal teas won’t break your fast (8).

Although intermittent fasting has been linked to a number of health benefits, it’s important to know that intermittent fasting is unnecessary to improve health.

Whether you want to lose body fat, reduce your disease risk, or increase your longevity, there are many other ways to achieve these goals without using fasting protocols.

If you’re interested in trying out intermittent fasting, check out this comprehensive guide.

Working with a registered dietitian can also help you decide whether intermittent fasting is the right choice for your specific needs and health goals.

Summary

If you’re interested in trying intermittent fasting, stick with a method that has research to back its potential benefits, such as time-restricted feeding, and speak with a medical professional or registered dietitian first.

Dirty fasting involves consuming a small number of calories during fasting windows.

Proponents of dirty fasting suggest that this method makes sticking to fasting regimens easier, but dirty fasting is not technically fasting. If you’re taking in calories — no matter whether it’s a small number — you may break your fast.

The only way to ensure you’re in a fasted state is to forgo all calories during your fasting window.

Just one thing

While intermittent fasting has been linked to health benefits, it’s not necessary for optimal health. Following a nutrient-dense diet, getting plenty of restful sleep, engaging in daily activity, and managing stress are much more important for keeping your body and mind healthy.

If you’re interested in trying intermittent fasting, it’s best to try an evidence-based version like the 16:8 method rather than dirty fasting.

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Dirty Fasting: Effectiveness, Recommendation, and More (2024)

FAQs

Is dirty fasting still effective? ›

Summary. Dirty fasting may provide some of the same health benefits as traditional fasting methods, like weight loss, but it may not offer the exact same benefits as completely abstaining from calorie intake during fasting windows.

What are the rules for dirty fasting? ›

The rules of dirty fasting differ depending on who you ask. Some websites that promote dirty fasting say that any food or beverage during the fasting hours is OK, as long as it's less than 100 calories. In contrast, other sources only sanction high-fat foods, which don't immediately spike insulin.

How to properly dirty fast? ›

This differs from traditional fasting or “clean” fasting, which restricts all foods and calorie-containing beverages. People who practice dirty fasting will typically consume up to 100 calories during their fasting window. This may include some milk and sweetener in their coffee or a cup of bone broth.

Can you get autophagy with dirty fasting? ›

It promotes autophagy by providing just enough dirty fasting calories to keep the body functioning but not enough to stop autophagy from happening. Autophagy is the process by which cells clear out their own waste products and broken parts, like clogged arteries or old cells.

How many days should you fast to detox your body? ›

Many medical experts agree that a one-day fast can feel great. But extending beyond three days can begin to cause harm, especially if you have other medical conditions, such as diabetes or heart disease. “A fast longer than a day or two can deplete vitamins, minerals and electrolytes,” Dr. Hopkins says.

What foods are good for dirty fasting? ›

The following are ok to eat and drink during a dirty fast: Non-Caloric Beverages: These include water, black coffee, herbal tea, sparkling water, and other drinks with no added sugars or milk. Low-Calorie Foods: A piece of fruit, raw vegetables like celery or cucumber, or a small handful of nuts can be consumed.

How many calories break a fast autophagy? ›

Autophagy and gut rest fasts prohibit any caloric substances from passing your lips. Even one or two calories can be enough to stop autophagy and rouse your gut out of its fasted resting state. This means that virtually all foods, beverages, powders, pills, and even breath mints and gum chewing are off limits.

What is the max calories to stay in fasted state? ›

The general rule of thumb is that if you stay under 50 calories, then you'll remain in the fasted state.

How long does it take for 16:8 intermittent fasting to work? ›

Additionally, it will take your body a while to get used to this new eating schedule. So don't expect results right away. You may need to wait between 2 and 4 weeks to see or feel any results.

How do I know if I'm in autophagy? ›

A key sign of autophagy is reduced appetite. It's likely due to changed levels of hormones like glucagon and insulin. Specifically, levels of glucagon tend to increase during autophagy. Glucagon helps manage your blood sugar levels and has been shown to suppress appetite ( 6 , 10 , 11 ).

What is the best exercise for autophagy? ›

Conclusion. This study demonstrated that long-term resistance training might be the best exercise for increasing autophagy in humans. The beneficial health effects of other exercise types, such as endurance training, might be via mechanisms other than activated autophagy.

What knocks you out of autophagy? ›

What turns off autophagy? Eating. Glucose, insulin (or decreased glucagon) and proteins all turn off this self-cleaning process. And it doesn't take much.

Can you fast if your body is not clean? ›

The fast of one who has intercourse with his wife at night and wakes up in the morning in a state of janabah (major ritual impurity) is still valid, as is the fast of one who becomes junub in his sleep, whether at night or during the day.

How effective is dry fasting? ›

There is evidence that dry fasting causes weight loss. Ramadan is a holy month during which Muslims abstain from all food and drink from sunrise to sunset every day. A study of 240 people who fasted for at least 20 days during Ramadan found that after Ramadan, body weight and body mass index (BMI) decrease in everyone.

What is the hardest fasting method? ›

Alternate day fasting is an extreme form of intermittent fasting, and it may not be suitable for beginners or those with certain medical conditions. It may also be difficult to maintain this type of fasting in the long term.

Will 1 calorie break a fast? ›

Technically speaking, eating or drinking any calories breaks a fast.

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