How to Fast: Fasting Foods That Won’t Break Autophagy

Calorie Restriction, Longevity

To keep us in fasting mode the blood sugar should not get too much higher than 100 mg/dL and if it goes to 120 the autophagy is suspended. Fasting foods are limited to 20 calories per serving.
Milos Pokimica

Written By: Milos Pokimica

Medically Reviewed by: Dr. Xiùying Wáng, M.D.

Updated February 9, 2024

Key Takeaways:

– One of the ways to trigger autophagy is to fast. When you fast, you deprive your body of nutrients, and your cells have to rely on their own reserves for energy.
– If you want to trigger autophagy, you need to lower your insulin, mTOR, and AMPK levels. The easiest way to do that is by fasting for 14 hours or more.
– There is no definitive answer to how many calories would break autophagy, as it may depend on several factors, such as your body weight, metabolism, activity level, and type of food or drink.
– Some experts suggest that anything more than 10 to 15 calories per hour could stop autophagy therefore fasting foods we can eat are limited to less than 20 calories per serving.
– Some average estimate is that one gram of carbohydrate can raise blood sugar by about 4 points on average. This means that to raise blood sugar by 1 point, you would need about 0.25 grams of carbohydrate, which is equivalent to about 1 calorie.
– To keep you in fasting mode the blood sugar should not get too much higher than 100 and if it goes to 120 the autophagy is suspended. Regular fasting levels of blood glucose are below 100 mg/dL. To keep autophagy we need to be below 100.
– To stay in range a safe option would be not to eat more than 20 calories in one meal.
– There are no fasting foods that can be eaten without any limits during a fast that have zero or low calories without breaking the fast or stopping autophagy. However, some fasting foods and drinks that are very low in calories or have zero calories may not have significant effects on fasting or autophagy if consumed in moderation and with caution.
– If you want to drink water kefir without breaking your fast or stopping autophagy, you may want to limit your intake to a small amount. No more than one cup in two hours.
– Beet kvass is not a zero-calorie drink, and it may break your fast or stop autophagy if you consume it during fasting in an amount of more than one cup.
– Fermented vegetables are generally low in calories. If you don’t want to break the fast keep the portion below 20 calories.
– Coffee can quickly stimulate autophagy by activating AMPK and inhibiting mTORC1.
– Coffee can maintain autophagy by keeping mTORC1 low, but not by keeping AMPK high.
– The beneficial effects of coffee might be due to the polyphenols that are present in coffee.
– Coffee can mimic caloric restriction, which is a well-known way of extending lifespan and preventing diseases, by reducing the acetylation levels of cellular proteins.
– The evidence for the effects of tea on autophagy during fasting is not very clear and there are a lot of different herbal teas available.
– Some of the teas like green tea are also believed to be able to suppress appetite during the fast.
– All of the teas however are free of calories and would not break the autophagy if consumed during the fast.
– Herbs and spices are a great way to add flavor and aroma to your dishes without adding too many calories.
– Some studies suggest that apple cider vinegar may help lower blood sugar levels and boost weight loss, both of which are common goals for people who fast (Petsiou et al., 2014) (Lim et al., 2016).
– Moreover, apple cider vinegar may help suppress your appetite and increase your feeling of fullness, which can help you eat less during your eating window (Darzi et al., 2014).
– Apple cider vinegar contains very few calories and carbs, so it won’t break your fast or kick you out of autophagy. In fact, it may even enhance ketosis by increasing the production of ketones in the liver.

Autophagy.

Have you ever wondered what happens to the cells in your body when they die or get damaged? Do they just pile up and create problems, or do they get disposed of somehow? The answer is that your body has a natural way of recycling and renewing itself, and it’s called autophagy.

Autophagy comes from the Greek words “auto” meaning self and “phagy” meaning eating. So, autophagy means self-eating. It’s a process where your cells break down and reuse their components, such as proteins and organelles. This way, your body can get rid of the old and inefficient parts, and replace them with new and functional ones.

Autophagy is essential for maintaining the balance and health of our cells. It helps to prevent the accumulation of damaged cells, which can lead to serious diseases such as cancer, diabetes, and neurodegeneration.

One of the ways to trigger autophagy is to fast. When you fast, you deprive your body of nutrients, and your cells have to rely on their own reserves for energy.

This activates autophagy, which cleans up the waste and recycles the useful materials. Fasting can also induce a type of cell death called autophagy-induced cell death, which targets the cells that are damaged or mutated beyond repair. This is different from another type of cell death called apoptosis, which is more controlled and regulated.

Fasting can have many benefits for your health, such as boosting your immune system, reducing inflammation, improving metabolism, and extending your lifespan. However, fasting also has some drawbacks, such as losing some muscle mass. When you fast, your body first uses up the glycogen stored in your liver and muscles. Then, it switches to burning fat for fuel. But it also breaks down some amino acids from your muscles to make glucose for your brain and other organs. This means that you will lose some muscle mass along with fat.

Summary:

Autophagy is your body’s natural self-eating process that recycles damaged cells and components, promoting health and longevity. Fasting is a key way to trigger this process for cleaner cells and potential health benefits like reduced inflammation and boosted immunity.

How to Trigger Autophagy.

In today’s world, food is always available, and we rarely fast for long periods. This means that we miss out on the benefits of autophagy, such as:

Reducing inflammation and oxidative stress
Preventing diseases like cancer, diabetes, and Alzheimer’s
Enhancing brain function and memory
Slowing down aging and extending lifespan

So how can we activate autophagy without starving ourselves?

The answer is simple: by fasting for 14 hours or more (Yang et al. 2017).

There are three main pathways that regulate autophagy (Alers et al., 2012):

Insulin: This hormone responds to carbohydrates and proteins in your blood. When insulin is high, it signals that you have enough energy and stops autophagy. When insulin is low, it signals that you need to use your stored energy and starts autophagy.
mTOR: This enzyme responds to proteins in your cells. When mTOR is high, it signals that you have enough building blocks for growth and stops autophagy. When mTOR is low, it signals that you need to recycle your old parts and starts autophagy.
AMPK: This enzyme responds to the energy level in your cells. When AMPK is high, it signals that you have low energy and starts autophagy. When AMPK is low, it signals that you have high energy and stops autophagy.

If you want to trigger autophagy, you need to lower your insulin, mTOR, and AMPK levels. The easiest way to do that is by fasting for 14 hours or more.

When you fast, your insulin drops because you are not eating any carbohydrates or proteins. Your mTOR drops because you are not eating any proteins. And your AMPK rises because your cells are running low on energy.

These changes activate glucagon, a hormone that opposes insulin and stimulates autophagy. Glucagon tells your body to break down your stored fat and use it as fuel. This process also produces ketones, which are molecules that can cross the blood-brain barrier and provide energy for your brain.

As a result, fasting for 14 hours or more can boost your metabolism, burn fat, improve brain function, and activate autophagy.

But what if you don’t want to fast for so long? Is there a way to induce autophagy faster? Yes, there is. You can use exercise and nutrition to enhance the effects of fasting.

Exercise can increase AMPK levels by depleting glycogen or in other words the energy in your muscles. This can also lower insulin and mTOR levels by increasing glucose uptake and protein breakdown. Therefore, exercise can stimulate autophagy even if you are not fasting for a full 14 hours. However, you would have to do fasted cardio which is very hard to do for most people. If you have any level of insulin sensitivity below optimal it would also lead to hypoglycemia.

Nutrition can also influence autophagy by modulating insulin and mTOR levels. Some foods can lower insulin and mTOR levels by providing antioxidants, polyphenols, or ketones. These include green tea, coffee, and apple cider vinegar. Other foods can raise insulin and mTOR levels by providing carbohydrates or proteins. These include bread, pasta, rice, potatoes, beans, meat, dairy, eggs, and soy.

Therefore, nutrition can either enhance or inhibit autophagy depending on what you eat.

2016 Nobel Prize- Physiology and Medicine for advances in Autophagy

Summary:

Because food is readily available today, we miss out on autophagy’s benefits like lowered inflammation and disease risk. Fasting for 14 hours activates this process. Exercise and certain foods like green tea can also help.

Fasting Foods That Will Not Stop Autophagy.

There is no clear consensus on what exactly breaks a fast or stops autophagy.

There is no definitive answer to how many calories would break autophagy, as it may depend on several factors, such as your body weight, metabolism, activity level, and type of food or drink.

However, some experts suggest that anything more than 10 to 15 calories per hour could stop autophagy therefore fasting foods we can eat are limited to less than 20 calories per serving.

However, this also means that even a small amount of calories like cream or sugar in the coffee could break the fast and autophagy.

Therefore, if you want to maintain autophagy, it is best to avoid any foods or beverages that contain calories during your fasting period. You can drink water, black coffee, or unsweetened tea, as they have zero or very low calories and may even enhance autophagy. You can also take supplements that support autophagy, such as spermidine, which is a natural compound found in some foods.

Generally speaking, any food or drink that contains calories will break a fast and potentially interfere with autophagy. Therefore, it is best to avoid any foods or beverages that provide energy, such as:

Sugar, honey, syrup, and other sweeteners
Milk, cream, cheese, and other dairy products
Meat, poultry, fish, eggs, and other animal products
Nuts, seeds, oils, butter, and other fats
Grains, bread, pasta, rice, and other starches
Fruits, juices, smoothies, and other sugary drinks
Alcohol, soda, energy drinks, and other caffeinated beverages

Some foods and drinks that are very low in calories or have zero calories may not break a fast or stop autophagy. However, some of them may still have some effects on your metabolism or hormone levels. Therefore, it is advisable to consume them in moderation and with caution. Some examples are:

Water: The only truly zero-calorie food is water that assists in weight loss and other benefits. It keeps you hydrated during fasting with no calories to consume.
Coffee and tea: Unsweetened black coffee and tea are very low in calories and may even boost autophagy by stimulating the production of ketones. However, adding sugar, milk, creamer, or sweetener will break a fast and stop autophagy. Also, caffeine may affect your sleep quality and cortisol levels.
Apple cider vinegar: Diluted apple cider vinegar may have some benefits for blood sugar control and appetite suppression. However, it also contains some calories and acetic acid, which may affect your digestion and tooth enamel.
Bone broth: Bone broth is a liquid made from simmering animal bones and connective tissue. It is rich in collagen. However, it also contains some calories and may stimulate the release of insulin.
Gum and mints: Sugar-free gum and mints may help curb your appetite and freshen your breath during fasting. However, they also contain artificial sweeteners like xylitol or sorbitol, which may have some effects on your gut bacteria and blood sugar levels.

In summary, there are no fasting foods that can be eaten without any limits during a fast that have zero or low calories without breaking the fast or stopping autophagy. However, some fasting foods and drinks that are very low in calories or have zero calories may not have significant effects on fasting or autophagy if consumed in moderation and with caution.

Moderation means no more than 20 calories in total.

Summary:

While anything with calories technically breaks a fast and potentially hinders autophagy, some low-calorie options like black coffee might be okay in moderation (under 20 calories). Ultimately, stick to zero-calorie choices like water for guaranteed autophagy activation during your fast.

Blood Sugar Levels and Fasting.

There is no simple answer to how many calories it takes to raise blood sugar level by 1 point, as it depends on several factors, such as your body weight, metabolism, activity level, and type of food or drink.

However, some average estimate is that one gram of carbohydrate can raise blood sugar by about 4 points on average. This means that to raise blood sugar by 1 point, you would need about 0.25 grams of carbohydrate, which is equivalent to about 1 calorie.

However, this is only a rough estimate, and the actual effect of carbohydrates on blood sugar may vary from person to person and from food to food. Some factors that can influence how carbohydrates affect blood sugar are:

The glycemic index (GI) of the food. GI is a measure of how quickly a food raises blood sugar compared to pure glucose. Foods with a high GI (such as white bread, candy, or soda) raise blood sugar faster and higher than foods with a low GI (such as whole grains, beans, or vegetables).
The glycemic load (GL) of the food. GL is a measure of how much carbohydrate is in a serving of food and how it affects blood sugar. GL takes into account both the quantity and quality of carbohydrates in a food. Foods with a high GL (such as large portions of high-GI foods) have a greater impact on blood sugar than foods with a low GL (such as small portions of low-GI foods).
The fiber content of the food. Fiber is a type of carbohydrate that is not digested or absorbed by the body. Fiber can slow down the digestion and absorption of other carbohydrates in the same meal, resulting in a lower and more gradual rise in blood sugar. Foods that are high in fiber (such as fruits, vegetables, nuts, and seeds) tend to have a lower GI and GL than foods that are low in fiber (such as refined grains, sweets, and juices).
The physical activity level. Physical activity can lower blood sugar by increasing the use of glucose by the muscles and improving insulin sensitivity. However, the effect of exercise on blood sugar depends on the type, intensity, duration, and timing of the activity. Exercise before or after a meal can also affect how the meal influences blood sugar.

To keep you in fasting mode the blood sugar should not get too much higher than 100 and if it goes to 120 the autophagy is suspended. Regular fasting levels of blood glucose are below 100 mg/dL. To keep autophagy we need to be below 100.

Fasting	2 hours after a meal
70–99 mg/dL	Less than 140 mg/dL

For example, to raise blood sugar from 70 to 99 mg/dL, you would need to consume about 29 calories, assuming that one gram of carbohydrate raises blood sugar by about 4 points on average. If we have an average blood fasting sugar in let’s say 75 to 85 range, 30 calories could potentially elevate our blood sugar above 100.

To stay in range a safe option would be not to eat more than 20 calories in one meal.

It also depends on the GI index of the food. We could potentially eat a meal with more than 30 calories if the meal has a lot of fiber and no free sugars.

However, this is only a rough estimate, and the actual effect of calories on blood sugar may vary depending on several factors, such as your body weight, metabolism, activity level, and type of food or drink.

Summary:

While one calorie can raise blood sugar by roughly one point, individual responses vary based on metabolism, food type, and GI. To stay in fasting mode (blood sugar below 100), avoid exceeding 20 calories per “meal” during your fast. Opt for high-fiber, low-sugar choices to potentially increase your calorie limit.

Water Kefir.

The lowest-calorie vegetable juices are celery juice and tomato juice, with only 42 and 41 calories per cup, respectively. These juices are also rich in vitamins, minerals, and antioxidants that can benefit your health. However, it is still too many calories if we don’t want to break the autophagy and fast.

This means that any vegetable juice is forbidden during the fast. Also, you should be aware that some vegetable juices may contain added sugar, salt, or preservatives that can increase their calorie content and reduce their nutritional value.

We need vegetable juice without sugar. And we can find the answer in fermentation.

Water kefir is a fermented drink made with water kefir grains, which are a symbiotic culture of bacteria and yeast. Water kefir grains feed on sugar, which is usually added to the water along with some dried fruits. Water kefir is a probiotic beverage that can benefit your gut health and immune system, it has the full spectrum of antioxidants, minerals, and vitamins that were present in the juice before fermentation but with low calories. Most of the sugar would be fermented by the bacteria culture.

Probiotic culture is beneficial for gut health and the immune system, but live culture also consumes some of the sugar in the water kefir during the fermentation process. However, they do not eat all of the sugar, and some fructose remains in the finished drink usually a couple of grams per cup.

Therefore, water kefir is not a zero-calorie drink, and it may break your fast or stop autophagy if you consume it excessively during fasting. The amount of sugar in water kefir depends on several factors, such as fermentation time and temperature, and the type and amount of flavoring. On average, water kefir contains about 2 to 5 grams of sugar per cup, which is much lower than soda or juice, but still enough to provide some calories to elevate blood sugar above 100 if we drink too much of it.

If you want to drink water kefir without breaking your fast or stopping autophagy, you may want to limit your intake to a small amount. No more than one cup in two hours.

You may also want to avoid adding any sweeteners or fruit juices to your water kefir, as they will increase the sugar content. You can still enjoy the fizzy and tangy taste of water kefir by adding some herbs, spices, or low-sugar fruits (such as berries or citrus) during the second fermentation. Also, ferment the kefir to the end to decrease the sugar content as much as possible.

Therefore, the calorie count of water kefir can vary from batch to batch and from recipe to recipe. You can use a nutrition calculator or a food scale to estimate the calories of your water kefir based on the ingredients you use. You can also adjust the sugar amount, fermentation time, and flavoring to suit your taste and preference.

Summary:

While vegetable juices are packed with nutrients, their calorie content makes them off-limits during autophagy-focused fasts. Water kefir, a fermented drink with gut-friendly bacteria, emerges as a lower-calorie alternative. However, its remaining sugar (2-5g per cup) requires moderation: stick to no more than a cup every two hours to avoid breaking your fast and hindering autophagy.

Beet Kvas.

Beet kvass is a fermented drink made from beets, salt, and water. It is rich in probiotics, vitamins, minerals, antioxidants, and phytonutrients. Here are some nutrition facts for beet kvass:

A 6-ounce (177 ml) serving of beet kvass contains about 16 to 72 calories, depending on the amount of sugar and flavoring added.
Beet kvass contains about 2 grams of dietary fiber, 1 gram of protein, and 6 grams of carbohydrates per 6-ounce serving.
Beet kvass is a good source of B vitamins (including folate) and vitamin C, which are essential for energy production, immune function, and collagen synthesis.
Beet kvass also provides minerals such as iron, calcium, magnesium, potassium, and manganese, which are important for blood formation, bone health, muscle function, nerve transmission, and antioxidant defense.
Beet kvass contains probiotics and food enzymes, which are beneficial for gut health, digestion, and immunity. Probiotics are live microorganisms that can restore the natural balance of gut bacteria and prevent or treat various gastrointestinal disorders. Food enzymes are substances that help break down food and enhance nutrient absorption.
Beet kvass is rich in antioxidants and phytonutrients such as betalain, which is a pigment that gives beets their red color. Betalain has anti-inflammatory, anti-cancer, and detoxifying properties. It can also help lower blood pressure, improve blood flow, and protect the liver.

The calorie count of beet kvass without any added sugar or flavors is not easy to determine, as it may vary depending on the fermentation time and temperature.

However, a rough estimate is that a 6-ounce (177 ml) serving of plain beet kvass contains about 16 calories. This is much lower than most fruit juices or sodas, which can have over 100 calories per serving.

However, it is still not a zero-calorie drink, and it may break your fast or stop autophagy if you consume it during fasting in an amount of more than one cup.

Watch the video below to learn how to make homemade water kefir probiotic beet juice soda, which contains higher levels of antioxidants and probiotics than fresh beet juice and is low on calories.

“Make a Soda Out of Anything With Fermentation.” YouTube, uploaded by Joshua Weissman, Aug 9, 2019, https://youtu.be/vTBJ-kO41YM

Summary:

Beet kvass, a fermented beet drink, boasts impressive health benefits like gut health support, antioxidant power, and rich vitamin and mineral content. While its calorie count varies based on fermentation and additives, plain beet kvass packs a mere 16 calories per 6-ounce serving, making it a potentially low-calorie alternative to sugary drinks during fasts (stick to one cup max).

Fermented Vegetables.

Some vegetables that are low in sugar are cucumbers, celery, lettuce, spinach, kale, and broccoli.

If we ferment these vegetables the result would be the same as with water kefir fermentation. Lower calorie end product that has the potential not to break our fast if we consume a small amount.

The calorie of fermented vegetables depends on the type and amount of ingredients used, as well as the fermentation time and temperature. Here are some approximate values for a 100-gram (3.5-ounce) serving of some common fermented vegetables based on the assumption that fermentation reduces the carbohydrate content by about 10%:

Sauerkraut: 19 calories
Kimchi: 22 calories
Fermented cucumbers: 11 calories
Fermented celery: 14 calories
Fermented lettuce: 12 calories
Fermented spinach: 18 calories
Fermented kale: 25 calories
Fermented broccoli: 23 calories

As you can see, fermented vegetables are generally low in calories. If you don’t want to break the fast keep the portion below 20 calories.

Also, there is a difference between pickled vegetables for example pickled cucumbers and fermented vegetables. Pickled vegetables are vegetables that have been preserved in a hot vinegar solution, which kills any microorganisms and enzymes on the food and does not lower the calorie count. Fermented vegetables are vegetables that have been salted and left at room temperature, which allows beneficial bacteria and yeast to grow by eating sugar and producing lactic acid. The lactic acid preserves the vegetables and also enhances their flavor and nutrition.

Summary:

While low-sugar veggies like cucumber and celery shine in fermented form, their calorie count still matters during fasts. Stick to portions below 20 calories (think a few bites) and remember, pickled veggies are different and don’t offer the same low-calorie advantage.

Coffee.

A cup of regular black coffee brewed from ground beans has only about 2 calories. That’s almost nothing compared to other drinks. A cup of black espresso has even less, just 1 calorie. That’s because espresso is made with less water and more finely ground beans.

Sugar and cream will increase the calorie count of your coffee, depending on how much you use. For example, one teaspoon of sugar has about 16 calories, and one tablespoon of half-and-half has about 20 calories. So if you add one teaspoon of sugar and one tablespoon of half-and-half to your coffee, you’ll end up with about 38 calories in your cup.

Of course, calories are not the only thing to consider when drinking coffee. Coffee also contains caffeine, which is a stimulant that can affect your sleep quality and cortisol levels. Cortisol is a hormone that regulates your stress response and metabolism. Too much caffeine can increase your cortisol levels and make you feel anxious, jittery, or restless. It can also interfere with your sleep cycle and make it harder for you to fall asleep or stay asleep. Therefore, it is advisable to limit your intake of coffee and drink it only in moderation.

How does it activate the process of autophagy?

A recent study explored these questions by looking at the effects of coffee on the energy sensors and protein acetylation levels in mice (Pietrocola et al., 2014). The researchers gave the mice different doses of coffee, either with or without caffeine, and measured the activity of two important energy sensors: AMPK and mTORC1. AMPK is a protein that senses low energy levels and stimulates autophagy. mTORC1 is a protein complex that senses high nutrient levels and inhibits autophagy. The researchers also measured the acetylation levels of cellular proteins, which can affect their function and stability.

The researchers found that coffee can affect both energy sensors and protein acetylation in different ways, depending on the duration and dose of coffee administration. When they gave the mice coffee, they saw a short-term increase in AMPK activity and a decrease in mTORC1 activity in all organs within one to four hours. This was true for both caffeinated and decaffeinated coffee.

This means that coffee can quickly stimulate autophagy by activating AMPK and inhibiting mTORC1.

However, when they gave the mice coffee in their drinking water for 16 days, they saw a long-term decrease in AMPK activity and a sustained decrease in mTORC1 activity in all organs. This was true for both 1% and 3% coffee, but not for 10% caffeinated coffee, which caused weight loss in the mice.

This means that coffee can maintain autophagy by keeping mTORC1 low, but not by keeping AMPK high.

The researchers also found that coffee can reduce the acetylation levels of cellular proteins in all organs within one to four hours after gavage. This was true for both caffeinated and decaffeinated coffee. They found that coffee reduced protein acetylation both in the cytoplasm and in the nuclei of liver, heart, and muscle cells.

The researchers speculated that the beneficial effects of coffee might be due to the polyphenols that are present in coffee.

Polyphenols are natural compounds that have antioxidant and anti-inflammatory properties. They might also stimulate autophagy by interacting with cellular receptors or signaling pathways.

In summary, this study showed that coffee can induce autophagy in mice by different doses and routes of administration and that this effect does not depend on caffeine content. This suggests that coffee might have a positive impact on your health by activating this natural self-cleaning mechanism in your cells.

It also showed that coffee can mimic caloric restriction, which is a well-known way of extending lifespan and preventing diseases, by reducing the acetylation levels of cellular proteins.

Summary:

Surprisingly, black coffee (around 2 calories per cup) can boost autophagy, your body’s cellular clean-up process, without breaking your fast. It works by activating AMPK and inhibiting mTORC1, both key players in autophagy. Enjoy it black for maximum benefit and consider its potential impact on sleep and cortisol levels.

Tea.

Tea is a zero-calorie beverage that can hydrate your body during a fast. Tea also contains polyphenols, which are natural compounds that have antioxidant and anti-inflammatory properties. Some studies have suggested that polyphenols can stimulate autophagy.

However, the evidence for the effects of tea on autophagy during fasting is not very clear and there are a lot of different herbal teas available.

Some of the teas like green tea are also believed to be able to suppress appetite during the fast.

A recent systematic review tried to answer these questions by examining the evidence from 32 studies that tested the effects of different bioactive phytochemicals on appetite and satiety (Stuby et al., 2019). The studies involved adults who were overweight or obese, but otherwise healthy. The review focused on the most commonly used plants, such as green tea, red pepper, and coffee.

The results were not very convincing. The review found that none of the plants tested in several trials showed a consistent positive effect on appetite or satiety. In other words, there was no clear evidence that any of the bioactive phytochemicals could help people eat less or feel more satisfied including green tea and coffee. Moreover, the review found that only a few side effects were reported, but none serious. This means that the bioactive phytochemicals were generally safe to use, but not very effective.

The review also explained the possible mechanisms of action of these natural remedies. They may act on different targets in your body, such as hormones in your gut (such as GLP-1 or ghrelin) or receptors in your nervous system (such as TRPV1). These targets may affect your hunger and fullness signals. However, the exact mechanisms are still not fully understood.

The review concluded that the current evidence for the use of bioactive phytochemicals as appetite suppressants or satiety enhancers is mostly inconclusive.

More systematic and high-quality studies are needed to determine the benefits and safety of these natural remedies for weight loss. Also, the quality and composition of these food supplements may vary widely, since they are not regulated as strictly as pharmaceutical drugs. They may also interact with other medications and cause adverse events.

To conclude it is unlikely that green tea would significantly suppress appetite during fast but this does not mean that green tea and other herbal teas do not have other potent health benefits. The health benefits of herbal medicine are outside of the scope of this article and if you want to drink tea during the fast you should research the health benefits of every plant that you want to consume.

All of the teas however are free of calories and would not break the autophagy if consumed during the fast.

Summary:

While black coffee might offer a surprising autophagy boost, green tea’s appetite suppression claims remain inconclusive. Enjoy tea’s zero-calorie hydration during your fast, and remember, all herbal teas are zero-calorie and won’t break your fast.

Dried Herbs and Spices.

Herbs and spices are a great way to add flavor and aroma to your dishes without adding too many calories. However, some herbs and spices may have more calories than others, depending on their type and amount.

Salt: Salt has zero calories, as it is a mineral that does not provide any energy to the body. However, salt is also high in sodium, which can raise blood pressure and cause other health problems if consumed in excess.

Basil: Basil is a green herb that belongs to the mint family. It has 23 calories per 100 grams, and it can add a fresh and aromatic flavor to your soups, salads, pasta, and pizza. Basil also contains vitamins A, C, K, and B6, as well as minerals such as iron, calcium, magnesium, and manganese.

Chili flakes and black pepper are both low-calorie spices that can add heat and flavor to your dishes. Chili flakes are crushed red pepper flakes that have about 6 calories per teaspoon, while black pepper has about 5 calories per teaspoon.

Spice or Herb	Calories per teaspoon
Salt	0
Distilled vinegar	1
Red wine vinegar	1
Apple cider vinegar	1
Basil	1
Cress	1
Chives	1
Cilantro	1
Dill / Dill weed	1
Garlic salt	1
Black pepper	5
Chili flakes	6
Oregano	6
Parsley	6
Cumin, ground	8
Paprika	8
Chile powder	8
Thyme, dried	9
Rosemary, dried	9
Sage, dried	9

As you can see, most spices and herbs have less than 10 calories per teaspoon, and some have zero calories. You can use them to season your food without adding too many calories to your diet. However, you should also be careful about the sodium content of some spices, such as salt and garlic salt, as they can raise your blood pressure and cause other health problems if consumed in excess. You should also be aware of the potential interactions of some spices and herbs with certain medications or medical conditions. Therefore, it is advisable to consult your doctor or a dietitian before using any spices or herbs for health purposes.

Summary:

Most herbs and spices boast less than 10 calories per teaspoon, with salt and distilled vinegar offering calorie-free options. Just mind the sodium in some and consult a doctor before using them for health purposes.

Apple Cider Vinegar.

Apple cider vinegar is a versatile ingredient that can add flavor to dishes and provide some health benefits.

Apple cider vinegar is a fermented liquid made from crushed apples. It contains acetic acid, which is the main active ingredient that gives it its sour taste and health benefits.

Some studies suggest that apple cider vinegar may help lower blood sugar levels and boost weight loss, both of which are common goals for people who fast (Petsiou et al., 2014) (Lim et al., 2016).

Moreover, apple cider vinegar may help suppress your appetite and increase your feeling of fullness, which can help you eat less during your eating window (Darzi et al., 2014).

But the best part is that apple cider vinegar contains very few calories and carbs, so it won’t break your fast or kick you out of autophagy. In fact, it may even enhance your ketosis by increasing the production of ketones in your liver.

However, before you start chugging apple cider vinegar, there are some things you need to know. Here are some tips on how to take apple cider vinegar safely and effectively while fasting.

Don’t take too much. While some benefits have been observed with doses as high as 2 tablespoons (30 mL) per day, this amount may also cause some unpleasant side effects, such as tooth enamel erosion and digestive irritation (Anderson et al., 2021). A more moderate dose of 1–2 tablespoons (15–30 mL) per day should be enough to reap some of the benefits without risking your health.
Take it in capsules if you don’t like the taste. If you find the taste of apple cider vinegar too sour or unpleasant, you can opt for capsules instead. These contain dehydrated vinegar that can deliver the same benefits without the acidic flavor. Just make sure to follow the dosage instructions on the label and avoid products that contain added ingredients that may break your fast.
Avoid gummies and drinks. While apple cider vinegar gummies and drinks may seem like a convenient and tasty way to get your dose of vinegar, they are not suitable for fasting. These products often contain added sugar and calories that can interfere with your fast and kick you out of ketosis. Stick to plain apple cider vinegar or capsules instead.
Dilute it with water. Never drink apple cider vinegar straight, as this can damage your teeth and irritate your throat and stomach. Always dilute it with water before drinking it. A good ratio is 1 tablespoon (15 mL) of vinegar per 8 ounces (240 mL) of water. You can also add more water if you find it too strong.
Use a straw. To protect your teeth even more from the acidity of apple cider vinegar, drink it with a straw. This will help reduce the contact between the vinegar and your enamel, which can prevent erosion and sensitivity. After drinking apple cider vinegar, rinse your mouth with water and wait at least 30 minutes before brushing your teeth.

Apple cider vinegar is a natural and beneficial addition to your fasting routine. It may help lower your blood sugar levels, boost your weight loss, and enhance your ketosis. However, make sure to take it in moderation, dilute it with water, use a straw, and avoid gummies and drinks that contain added sugar and calories. By following these tips, you can enjoy the benefits of apple cider vinegar without breaking your fast or harming your health.

Summary:

Apple cider vinegar’s low calorie count and potential benefits like appetite suppression and ketosis enhancement make it a promising addition to your fast but remember to dilute it, use a straw, and avoid gummies or drinks with added sugars to keep it fast-friendly.

FAQ

A: Autophagy is a process where your cells break down and reuse their components, such as proteins and organelles. It means self-eating in Greek.

A: Autophagy is important for maintaining the balance and health of your cells. It helps to prevent the accumulation of damaged cells, which can cause diseases.

A: One of the ways to activate autophagy is to fast. Fasting deprives your body of nutrients, and forces your cells to rely on their own reserves for energy.

A: Fasting can have many benefits for your health, such as boosting your immune system, reducing inflammation, improving metabolism, and extending your lifespan.

A: Fasting can also have some drawbacks, such as losing some muscle mass. When you fast, your body breaks down some amino acids from your muscles to make glucose for your brain and other organs. This means that you will lose some muscle mass along with fat.

A: You can trigger autophagy by fasting for 14 hours or more. This will lower your insulin, mTOR, and AMPK levels, and activate glucagon and ketones. This will help your body break down fat and use it as energy.

A: You can trigger autophagy by exercise and nutrition by modulating your insulin and mTOR levels. Exercise can increase AMPK levels by depleting glycogen. Nutrition can lower or raise insulin and mTOR levels by providing antioxidants, polyphenols, ketones, carbohydrates, or proteins.

A: There is no clear consensus on what exactly breaks a fast or stops autophagy. However, some experts suggest that anything more than 10 to 15 calories per hour could stop autophagy. This means that even a small amount of calories like cream or sugar in the coffee could break the fast and autophagy.

A: Some foods or drinks that are very low in calories or have zero calories are water, black coffee, unsweetened tea, apple cider vinegar, bone broth, gum, and mints. However, they may still have some effects on your metabolism or hormone levels, so consume them in moderation and with caution. Moderation means no more than 20 calories in total.

A: Generally speaking, any food or drink that contains calories will break a fast and potentially interfere with autophagy. Therefore, it is best to avoid any foods or beverages that provide energy.

A: There is no simple answer to this question, as it depends on several factors, such as your body weight, metabolism, activity level, and type of food or drink. However, some average estimate is that one gram of carbohydrate can raise blood sugar by about 4 points on average. This means that to raise blood sugar by 1 point, you would need about 0.25 grams of carbohydrate, which is equivalent to about 1 calorie.

A: Normal fasting levels of blood glucose are below 100 mg/dL. Normal postprandial (2 hours after a meal) levels of blood glucose are less than 140 mg/dL.

A: To keep your blood sugar in fasting mode, you should not get too much higher than 100 mg/dL. If your blood sugar goes to 120 mg/dL or above, the autophagy (the process of cellular self-cleaning) is suspended. To keep autophagy active, you need to be below 100 mg/dL.

A: No, you cannot drink vegetable juice during fasting, as it will break your fast and stop autophagy. Vegetable juice contains calories, sugar, and sometimes additives that can interfere with your metabolic state.

A: Water kefir is a fermented drink made with water kefir grains, which are a symbiotic culture of bacteria and yeast. Water kefir grains feed on sugar, which is usually added to the water along with some dried fruits. Water kefir is a probiotic beverage that can benefit your gut health and immune system.

A: Water kefir is not a zero-calorie drink, but it has much fewer calories and sugar than soda or juice. On average, water kefir contains about 2 to 5 grams of sugar per cup, which translates to about 8 to 20 calories.

A: You can drink water kefir without breaking your fast or stopping autophagy if you limit your intake to a small amount. No more than one cup in two hours. You should also avoid adding any sweeteners or fruit juices to your water kefir, as they will increase the sugar content.

A: You can make your water kefir taste better and have less sugar by adding some herbs, spices, or low-sugar fruits (such as berries or citrus) during the second fermentation. You should also ferment the kefir to the end to decrease the sugar content as much as possible.

A: Some vegetables that are low in sugar are cucumbers, celery, lettuce, spinach, kale, and broccoli.

A: Fermentation reduces the calorie and sugar content of vegetables by about 10%, as the beneficial bacteria and yeast consume some of the sugar and produce lactic acid.

A: Fermented vegetables have different calorie counts depending on the type and amount of ingredients used, as well as the fermentation time and temperature. On average, a 100-gram (3.5-ounce) serving of fermented vegetables has about 15 to 25 calories.

A: You can eat fermented vegetables during fasting without breaking your fast or stopping autophagy if you limit your intake to a small amount. No more than 20 calories per serving.

A: Pickled vegetables are preserved in a hot vinegar solution, which kills any microorganisms and enzymes on the food and does not lower the calorie count. Fermented vegetables are salted and left at room temperature, which allows beneficial bacteria and yeast to grow by eating sugar and producing lactic acid. The lactic acid preserves the vegetables and also enhances their flavor and nutrition.

A: A cup of regular black coffee brewed from ground beans has only about 2 calories, and a cup of black espresso has even less, just 1 calorie.

A: Sugar and cream will increase the calorie count of your coffee, depending on how much you use. For example, one teaspoon of sugar has about 16 calories, and one tablespoon of half-and-half has about 20 calories.

A: Coffee can activate autophagy by affecting the activity of two important energy sensors: AMPK and mTORC1. AMPK is a protein that senses low energy levels and stimulates autophagy. mTORC1 is a protein complex that senses high nutrient levels and inhibits autophagy. Coffee can quickly stimulate autophagy by activating AMPK and inhibiting mTORC1 within one to four hours after drinking it. Coffee can also maintain autophagy by keeping mTORC1 low for longer periods of time.

A: Acetylation is a chemical modification that can affect the function and stability of cellular proteins. Coffee can reduce the acetylation levels of cellular proteins in all organs within one to four hours after drinking it. This can mimic caloric restriction, which is a well-known way of extending lifespan and preventing diseases.

A: Polyphenols are natural compounds that have antioxidant and anti-inflammatory properties. They might also stimulate autophagy by interacting with cellular receptors or signaling pathways. The polyphenols in coffee might be responsible for some of the beneficial effects of coffee on health.

A: Yes, tea is a zero-calorie drink that can hydrate your body during a fast.

A: Polyphenols are natural compounds that have antioxidant and anti-inflammatory properties. Some studies have suggested that polyphenols can stimulate autophagy, which is a natural self-cleaning mechanism in your cells.

A: No, there is no clear evidence that tea can suppress appetite or enhance satiety. A recent systematic review found that none of the bioactive phytochemicals in tea or other plants showed a consistent positive effect on appetite or satiety.

A: You can use spices and herbs to season your food without adding too many calories by using them sparingly and measuring them carefully. You can also choose the ones that have less or zero calories, such as salt, vinegar, basil, cress, chives, dill, garlic salt, black pepper, chili flakes, oregano, and parsley.

A: Basil and cilantro are both green herbs that belong to the mint family. They have about 1 calorie per teaspoon, and they can add a fresh and aromatic flavor to your dishes. They also contain vitamins and minerals that can benefit your health.

A: Chili flakes and black pepper are both low-calorie spices that can add heat and flavor to your dishes. Chili flakes have about 6 calories per teaspoon, while black pepper has about 5 calories per teaspoon.

A: Apple cider vinegar is a fermented liquid made from crushed apples. It contains acetic acid, which is the main active ingredient that gives it its sour taste and health benefits.

A: Apple cider vinegar may help lower blood sugar levels and boost weight loss by improving insulin sensitivity, reducing glucose absorption, and increasing fat oxidation.

A: Apple cider vinegar may suppress appetite and increase fullness by delaying gastric emptying, increasing satiety hormones, and reducing hunger signals.

A: Apple cider vinegar has very few calories and carbs, so it won’t break your fast or kick you out of autophagy. One tablespoon (15 mL) of apple cider vinegar has about 3 calories and 0.1 grams of carbs.

References:

Yang, J. S., Lu, C. C., Kuo, S. C., Hsu, Y. M., Tsai, S. C., Chen, S. Y., Chen, Y. T., Lin, Y. J., Huang, Y. C., Chen, C. J., Lin, W. D., Liao, W. L., Lin, W. Y., Liu, Y. H., Sheu, J. C., & Tsai, F. J. (2017). Autophagy and its link to type II diabetes mellitus. BioMedicine, 7(2), 8. https://doi.org/10.1051/bmdcn/2017070201
Alers, S., Löffler, A. S., Wesselborg, S., & Stork, B. (2012). Role of AMPK-mTOR-Ulk1/2 in the regulation of autophagy: cross talk, shortcuts, and feedbacks. Molecular and cellular biology, 32(1), 2–11. https://doi.org/10.1128/MCB.06159-11
Pietrocola, F., Malik, S. A., Mariño, G., Vacchelli, E., Senovilla, L., Chaba, K., Niso-Santano, M., Maiuri, M. C., Madeo, F., & Kroemer, G. (2014). Coffee induces autophagy in vivo. Cell cycle (Georgetown, Tex.), 13(12), 1987–1994. https://doi.org/10.4161/cc.28929
Stuby, J., Gravestock, I., Wolfram, E., Pichierri, G., Steurer, J., & Burgstaller, J. M. (2019). Appetite-Suppressing and Satiety-Increasing Bioactive Phytochemicals: A Systematic Review. Nutrients, 11(9), 2238. https://doi.org/10.3390/nu11092238
Petsiou, E. I., Mitrou, P. I., Raptis, S. A., & Dimitriadis, G. D. (2014). Effect and mechanisms of action of vinegar on glucose metabolism, lipid profile, and body weight. Nutrition reviews, 72(10), 651–661. https://doi.org/10.1111/nure.12125
Lim, J., Henry, C. J., & Haldar, S. (2016). Vinegar as a functional ingredient to improve postprandial glycemic control-human intervention findings and molecular mechanisms. Molecular nutrition & food research, 60(8), 1837–1849. https://doi.org/10.1002/mnfr.201600121
Darzi, J., Frost, G. S., Montaser, R., Yap, J., & Robertson, M. D. (2014). Influence of the tolerability of vinegar as an oral source of short-chain fatty acids on appetite control and food intake. International journal of obesity (2005), 38(5), 675–681. https://doi.org/10.1038/ijo.2013.157
Anderson, S., Gonzalez, L. A., Jasbi, P., & Johnston, C. S. (2021). Evidence That Daily Vinegar Ingestion May Contribute to Erosive Tooth Wear in Adults. Journal of medicinal food, 24(8), 894–896. https://doi.org/10.1089/jmf.2020.0108

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About the Author

Milos Pokimica

Milos Pokimica is a doctor of natural medicine, clinical nutritionist, medical health and nutrition writer, and nutritional science advisor. Author of the book series Go Vegan? Review of Science, he also operates the natural health website GoVeganWay.com

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