Mythbusting Clean and Dirty Fasting: What’s More Effective?


Intermittent fasting has become a popular method for weight loss and overall health improvement, with many different variations and approaches. However, not all fasting methods are created equal.

In this blog post, we’ll define the two main types of intermittent fasting – clean fasting and dirty fasting – debunk some common myths and show you why clean fasting is the superior approach in terms of health and weight loss.


What is clean fasting?

Clean fasting is a type of fasting where you follow an intermittent fasting protocol and restrict the intake of any calories throughout your fast, consuming only (sparkling) water, black coffee and plain herbal tea (without additives like milk, sugar, sweeteners or the like). The idea is to give your body a complete break during the fasting period which triggers a number of physical processes that are beneficial for our health.

When we practice clean fasting, our bodies switch from burning glucose (sugar) to burning fat. This metabolic state is called ketosis and usually occurs when the body’s glucose stores are emptied with the help of sufficiently long eating breaks.

Some people who follow a ketogenic diet and practice fasting state that consuming bulletproof coffee (a beverage made with coffee, MCT oil, and butter or ghee) while fasting will not disturb ketosis because it does not contain any carbs or protein. However, since it does contain calories and fat there is the potential risk that it breaks your fast and stops your body from entering a state of ketosis, which is why we’d recommend you to have it during your eating period only.

In addition to ketosis, fasting also boosts a physical process called autophagy, which means “eating the self.” During long periods of fasting (16 hours or more), our cells begin using damaged components to produce energy, which is a healthy process that can help avoid the risk of various diseases, improve mental health, and the body’s overall immunity.

Sometimes you find the information that clean fasting must be calorie free. Black coffee and herbal tea contain about five calories per cup and minimal amounts of carbs, fat, protein, and minerals. However, these amounts of calories and nutrients are considered to be too small to trigger an insulin response and disturb the body’s “metabolic switch” from burning carbs to burning fat as fuel. Research even shows that coffee and green tea can support your intermittent fasting success since they suppress appetite, provide antioxidants and boost the metabolism.

Nevertheless if you want to be on the safe side with your clean fasting routine, make sure not to drink more than 2 cups of coffee or tea during your fasting period and stick to water for the rest of the time.


What is dirty fasting?

Dirty fasting (also known as “lazy fasting”) is a less restrictive form of fasting that allows you to consume foods or beverages under 50 calories during your fasting period. Having for example milk or cream in your coffee, bone broth, infused water, chewing gums or diet sodas during your fasting window, is considered dirty fasting.

Although some practitioners of dirty fasting argue that consuming less than 50 calories will not break your fast, you can’t rely on staying in ketosis and autophagy phase, since there is a high risk that the consumption will trigger an insulin response. In addition, research indicates that even calorie-free drinks containing (artificial) sweeteners can cause a release of insulin.

You might have read on the internet that sweeteners won’t break your fast. However, the effect of sweeteners on blood sugar levels is a subject of ongoing research and is still not entirely clear.

Some studies suggest that certain sweeteners, such as aspartame and stevia, may not stimulate insulin secretion, while others, such as sucralose and saccharin, may have an effect on insulin levels.

It’s important to note that individual responses to sweeteners can vary. Some people may experience an increase in insulin secretion after consuming sweeteners, while others may not.


Why clean fasting beats dirty fasting at all levels

Clean fasting may seem daunting at first, but it is a straightforward approach. It’s not about turning your whole life upside down. It’s just about sticking to your fast in the right way.

Clean fasting is generally considered to be more effective than dirty fasting. It helps you achieve ketosis, which promotes weight and fat loss, and supports you in regulating blood sugar and insulin sensitivity.

Additionally, it increases cellular cleanup and repair processes that can slow aging processes, and reduces inflammation. Proper timeouts from eating also improve our digestive health, physical healing, mental clarity, sleep, and skin.

To put it in a nutshell: When practicing clean fasting you will benefit on many levels, physically or mentally.

And if you are struggling with weight loss, clean fasting may be the ultimate game changer, as it gives your fat loss an extra boost.

Dirty fasting, on the other hand, may seem easier to follow and might bring you results in terms of weight loss but in a less effective way. This is due to the fact that ketosis is not triggered during dirty fasting, thus there is also no increased fat burning. Strictly speaking, dirty fasting can not be considered real fasting, since the fasting state is disrupted through the release of insulin.

In addition, insulin spikes prevent autophagy, may cause fatigue and mood swings and can even lead to cravings and overeating during your eating periods, negating your fasting results.

And look at it from that perspective: Having a little milk in your coffee or a cup of bone broth will not drastically facilitate sticking to your fasting period, but it will cut you off from incredibly great effects, not allowing you to reap the full benefits of fasting. Actually a pity, isn’t it?


Clean vs. dirty fasting: the bottom line

As you’ve probably noticed, we take a pretty clear stand when it comes to clean and dirty fasting.

In our eyes, clean fasting is the ultimate tool to take your health and well-being to the next level. Therefore, we invite you to be open to something new, a little discipline, and change.

During your fasting period, you can choose between water, tea, and black coffee. This simple but effective rule can make all the difference and has been the game changer for many BodyFasters.

If you are still not convinced, give clean fasting a try for two weeks. A little discipline will help you make it happen easily. You will be grateful for taking this step, and we’re confident that you won’t regret it. Try clean fasting today and experience the ultimate game changer in your intermittent fasting journey.


In the BodyFast app you’ll find your optimal fasting plan, delicious recipes tailored to your fasting lifestyle, supportive weekly tasks, daily motivational Coachings, and more.


7 thoughts on “Mythbusting Clean and Dirty Fasting: What’s More Effective?

  1. Darice Hawkins Reply

    I Have lost > 30 over in a year doing 24 hrs fast 3x a week., but now I am stalled for several months. i do have have one cup of coffee with milk and splenda on fast days. Do you think doing a clear fast on those 3 days (black Coffee) might help me break the stall and lose my remaining 15 pounds?

    • Valerie Dratwa Reply

      Hello Darice,
      Firstly, congratulations on losing over 30 pounds in a year! That’s a significant achievement and demonstrates your dedication to your health and wellness. However, it’s not uncommon to experience a plateau after an initial period of weight loss. Our bodies can adapt to certain routines, and this might be why you’re finding it difficult to shed those last 15 pounds.To potentially break through your weight loss stall, we suggest trying a clear fast on your designated fasting days. This means avoiding any caloric intake during those fasting periods, including the milk and Splenda in your coffee. Give this approach a few weeks and closely monitor your progress. Remember to stay hydrated and consult a healthcare professional if needed. Stay committed and don’t hesitate to reach out for further support.:)

  2. Kerry D Montgomery Reply

    I am confused by the coffee/ water/ herbal tea references. I wonder why regular tea is not included. I drink black tea and green tea and sometimes even white tea but I prefer tea not herbal infusions. Can you explain why regular tea is not included?

  3. Dalia Reply

    Is having water with lemon considered dirty fasting? I have few slices of lemon in my water to help curb cravings.

    • Lara Reply

      Hello Dalia,

      You can add slices of lemon or other fruit to your water. Please note that you shouldn’t squeeze the lemon out. ☺️

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