What You Can Drink While Fasting Backed by Science

fasting | what to drink | water | tea | coffee | juice | diet soda

Intermittent fasting is a dietary style typically combined with a low-carb or keto diet. If you just started, the supposedly simple plan can quickly become complicated.

It alternates between feasting and fasting during fixed periods. In short, the rules for the fasting window are not different from prolonged fasting: extended fasts people do for stunning health benefits or spiritual reasons.

But few people know what to consume during a fasting period without breaking the fast.

For this reason, possibly the most crucial question is: What can I drink during fasting?

In this article, I work through all imaginable drinks and determine their effects on intermittent and prolonged fasting based on science.

What Is Intermittent Fasting?

During intermittent fasting, you eat within a certain period and fast the rest of the day.

Although there are various intermittent fasting schedules, the most popular is fasting during a 16-hour time frame.

With the most common intermittent fasting 16/8 schedule, one may eat only 8 hours per day, e.g., from noon to 8 PM.

However, you are allowed to drink around the clock. Therefore, we look closer at what you can drink during intermittent fasting without destroying its benefits.

What Should You Drink During Fasting?

To judge what one is allowed to drink during intermittent fasting, we must first find out why we are fasting.

In short, there are two primary reasons for intermittent fasting:

• Weight loss
• Health benefits

Although losing weight also causes health benefits, most of the positive effects of fasting in our body come from a process called autophagy.

Notably, both fat-burning (ketosis) and autophagy require low insulin levels. With this in mind, a third essential aspect of intermittent fasting arises:

• It increases insulin sensitivity,
• Improves blood sugar metabolism
• And thus fights metabolic diseases

Ketosis and Weight Loss

Since fasting is the most effective way to lower insulin levels, it is essential for weight loss. Accordingly, insulin is a crucial storage hormone in the human body.

Therefore, it is responsible for signaling cells to take up glucose from the bloodstream and store excess energy as fat or glycogen.

Furthermore, insulin blocks the enzyme that can break down body fat (Meijssen et al. 2001¹).

Accordingly, scientists can predict about 75% of weight gain and loss in overweight people by analyzing their insulin levels (Kong et al. 2013²).

The 16 hours of fasting cut off the supply of nutrients, lower insulin levels, and thus end the body’s storage mode.

The body can then break down the carbohydrate stores (glycogen). Once the glycogen stores are empty, your body can burn stored fat for energy.

This fat-burning process is called ketosis and, contrary to many myths, is an entirely natural mechanism that has ensured our species’ survival.

Nature has designed the body to build up fat reserves during abundance and tap into this body fat for energy when food is scarce.

Nowadays, instead of food shortages, we experience an endless summer and eat round the clock. Thus, we gain weight.

Therefore, intermittent fasting can help to restore the natural balance between feasting and fasting.

Insulin Resistance and Diabetes

As research shows, regular intermittent fasting improves insulin sensitivity.

Therefore, it reduces high insulin levels, improves blood-sugar metabolism, and eliminates excess sugar in the body.

Furthermore, it can even reverse insulin resistance and type-2-diabetes, which most diets alone simply can’t (Halberg et al. 2005³).

The cause of these metabolic diseases lies in the liver. Too much sugar and insulin cause insulin resistance in liver cells for years (Bawden et al. 2017⁴).

The result is a fatty liver. To get at the heart of many metabolic problems, you must burn off the deposited visceral fat in the liver.

The term visceral fat refers to the accumulation of fat in and around organs, which harms health.

But according to current studies, intermittent fasting, in particular, can burn this dangerous visceral fat more effectively than low-carb diets (Catenacci et al. 2016⁵).

However, intermittent fasting can only burn excess sugar and visceral fat if it is not interrupted by (liquid) food.

For example, drinking coffee without milk during intermittent fasting is crucial since this would cause blood sugar and insulin levels to skyrocket.

Fasting and Autophagy

Autophagy is decisive for the 16 hours of intermittent fasting. If you do not eat for 14 hours, you can induce autophagy (Yang et al. 2017⁶).

Since it’s a groundbreaking health benefit, the discovery of autophagy was honored with the Nobel Prize (Levine et al. 2017⁷).

When food is scarce, the body switches from growth to maintenance. Therefore, it starts autophagy, the intracellular recycling system that breaks down broken cell parts and drains toxins from the body.

But how can be determined if a drink stops autophagy?

For this reason, the human body has three essential nutrient sensors. In short, they switch the autophagy process on and off:

• Insulin: Sensitive to carbohydrates and proteins
• mTOR: Sensitive to proteins
• AMPK: Sensitive energy shortage in cells

AMP-activated protein kinase (AMPK) reacts when energy is supplied to cells – regardless of macronutrients. Therefore, besides carbohydrates and proteins, fat also inhibits autophagy.

Both AMPK and insulin activate mTOR (mechanistic or mammalian target of rapamycin).

Therefore, this enzyme essential for growth is the primary nutrient sensor, and as soon as you eat, it detects nutrient availability and overrides autophagy.

However, if nutrient supply is interrupted, cells react sustainably and use dysfunctional cell parts for energy production.

Once this intracellular recycling system is at work, it yields numerous health benefits (Raefsky et al. 2017⁸; Jiao et al. 2017⁹; Sasaki et al. 2017¹⁰; Nakamura et al. 2018¹¹):

• Fights dementia, Alzheimer’s, and Parkinson’s disease
• Prevents muscle and bone atrophy
• Reduces the risk of cardiovascular disease
• Slows down aging and increases healthspan

If we look closely at what you can drink during intermittent fasting, autophagy is the yardstick.

Since the nutrient sensors relevant to autophagy include insulin, it covers all mechanisms that can break your fast.

Can You Drink Water When Fasting?

Fasting means not eating. Nevertheless, drinking water in its purest form is allowed during intermittent fasting.

Consequently, some humans can get along for over a year without food but not without water (Stewart et al. 1973¹²).

Furthermore, Intermittent fasting aims at depleting carbohydrate stores, enabling the body to burn stored fat for energy production.

Since the body needs water to store carbohydrates as glycogen in the liver, kidneys, and muscles, you lose a lot of water during intermittent fasting.

Therefore, those who do not drink accordingly will experience keto flu symptoms during intermittent fasting, such as headaches or vertigo.

These minor physical ailments are usually due to a lack of minerals – primarily sodium – your body flushes out with the water.

In addition to the necessary fluid, water can also provide the body with minerals. However, nutrient sensors are not activated in this case. Therefore, water does not break an intermittent fast.

Besides, I recommend consuming more natural Himalayan or Celtic sea salt during the eating periods when intermittent fasting.

If you listen to your body, it will demand more salt anyway.

Since salt reduces the craving for sweets, increases insulin sensitivity, improves metabolism, and helps you lose weight, it’s good (Sakuyama et al. 2016¹³).

Carbonated Water

In my opinion, carbonated water is an outstanding choice when it comes to what you can drink during intermittent fasting.

On the one hand, it offers effects that excellently support intermittent fasting:

• It curbs the appetite,
• Helps with an upset stomach,
• Or even with cramping.

On the other hand, superior carbonated water can bring more than 100 mg per liter of the essential electrolytes magnesium, sodium, and calcium into the body.

Therefore, carbonated mineral water is the best choice. But only if you have access to natural, highly mineralized brands.

Here in Austria, we are blessed with incredible natural springs. But depending on your location, you might have to check labels carefully.

Hence, access to high-quality mineral water can provide electrolytes, even during extended fasts. In this case, you don’t need to fall back to bone broth to get them.

Flavored Sparkling Water

Although there is now flavored sparkling water with only natural flavorings, most products do not get by without sugar or sweeteners, which break the fast.

However, natural flavoring means that the flavoring agent has been extracted from a natural source product by a chemical process.

Unless other additives are included, natural flavors can be limited to minimal amounts of macronutrients, so they hardly affect autophagy. Nevertheless, such products are still scarce.

In case of doubt, I would not resort to flavored sparkling water. Besides, most flavored options don’t taste good.

If you want to bring more flavor into your intermittent fasting plan, maybe natural flavors from fruits could get a variety in the water.

Infused Water

A natural way is probably generally better if you want to flavor water.

For example, you can put a few slices of organic lime, lemon, orange, or cucumber in a carafe and fill it with water.

This way, you add a light natural aroma to the water that will not affect fasting significantly as long as you do not eat the slices.

However, this aid shouldn’t be overused. Once you are used to intermittent fasting, you can get along without it anyway.

Lemon Water

In addition to the lemon slices, a small splash of lemon moves in a grey zone during intermittent fasting.

Suppose you want to be on the very safe side. In that case, leaving a slice of organic lemon in the water is better, as the tiny amounts of calories come from carbohydrates, which technically can activate all three nutrient sensors.

Nonetheless, a splash of lemon will not negate all the benefits of fasting.

Since there is a low basic level of autophagy in the body at all times, it cannot be 100% deactivated immediately, especially not by relatively negligible amounts of macronutrients.

Coconut Water

Many believe in having found an excellent intermittent fasting drink in coconut water.

But that’s not the case since the lion’s energy share comes from sugar, unlike in coconut (*).

Furthermore, the proportion of electrolytes is much lower than one might think – no comparison to natural mineral water.

In summary, the supposedly natural coconut water fails as a drink during the fasting period. Therefore, we can now focus on other beverages that share some characteristics with coconut water.

Can You Drink Tea During Fasting?

Besides water, tea is the most popular beverage in the world. But there are countless varieties of tea. Therefore, we cannot generalize and dive into the specific teas individually to determine if you can drink them during fasting.

Green Tea

Green tea is probably the drink that has proved to be most effective in intermittent fasting over the decades.

Meanwhile, only coffee can contest this title. Like coffee, a cup of tea has about 2.5 calories – both with (*) and without caffeine (*).

Nevertheless, many experts agree that this minimal amount of macronutrients in tea is negligible.

As with coffee, studies on green tea suggest that it induces rather than prevents autophagy (Prasanth et al. 2019¹⁴).

Furthermore, all pure varieties of real tea are suitable for intermittent fasting. The degree of fermentation of the tea plant “Camellia Sinensis” determines the name of the tea:

• Unfermented – white tea
• Minimally fermented – Green tea
• Partially fermented – Oolong tea
• Fully fermented – black tea

Although all these teas are suitable, green tea provides the best properties for intermittent fasting due to its many active compounds (Crespy et al. 2004¹⁵; Hursel et al. 2013¹⁶; Dulloo et al. 2000¹⁷):

• Regulates blood sugar and prevents diabetes
• Boosts the metabolism
• Helps with fat burning
• Prevents cardiovascular diseases and cancer

Furthermore, real tea curbs the appetite, so it has already helped many people when fasting.

However, you should be careful with tea from coffee chains like Starbucks, which in most cases contain a lot of sugar (*) or at least sweeteners.

Herbal Tea

Although herbal and fruit tea is prevalent here in Central Europe, they are often big surprises. You usually cannot be sure what is inside.

Besides regular dried fruits, candied fruits often hide in fruit tea. Moreover, they often hide in herbal tea as well. And their sugar content will break a fast.

Accordingly, the variance in fruit tea is significant (*). Like green tea, it can contain almost none, just too many for intermittent fasting or many hidden carbohydrates.

Therefore, as with food purchases, the basic rule is to read the label carefully and avoid suspicious contents. The same applies to herbal tea, which performs better because it does not commonly contain dried fruits.

If you want to be safe, do not drink herbal or fruit tea during intermittent fasting.

Ginger and Chai Tea

In a broader sense, ginger and chai tea are pretty similar to regular herbal tea. If you can get the straight dried herbs in a tee specialty shop, you can drink the brewed tea during intermittent fasting.

Please keep your hands off instant mixes and chai from coffee shop chains (*), as they almost always contain additives that will break your fast.

If you are lucky, you can even get straight chai (*) or ginger tea in grocery stores, but always check labels before purchasing.

However, it’s not that easy to get it straight since most people drink chai as a latte (*). If the label says chai latte, it’s going to break your fast anyway.

On the other hand, ginger tea brewed with nothing else than freshly chopped ginger root and hot water should be fine, as long as you don’t eat the pieces (*).

Tea With Milk

Since 100 ml of milk contains not only 5 g of lactose but also approximately as much protein, it makes the difference (*).

Even a milk shot impairs intermittent fasting since it spikes blood sugar and insulin levels – mostly if it’s skimmed and low-fat.

Both milk powder and vegetable milk drinks are industrially produced and are not suitable for fasting due to their composition.

Only unsweetened almond milk moves in a grey zone. After the nut milk is remarkably thin, a splash in the tea will not necessarily break the fast.

The same applies to cinnamon, which also yields exciting health benefits.

Tea With Honey

Honey consists of over 80% of sugar (*). The fact that honey is natural doesn’t help much – table sugar is also obtained from “natural” beets.

Consequently, tea with honey is not allowed during intermittent fasting.

Tea With Sweetener

As you will see in the diet pop section, both natural and artificial sweeteners are problematic when fasting. They stimulate insulin even if they have no calories (Anton et al. 2010¹⁸).

As it prevents autophagy and fat burning, tea with sweeteners is not allowed during fasting.

Should You Drink Coffee While Fasting?

Although religiously motivated often forbids coffee, it does not generally impair intermittent fasting.

On the contrary, coffee does not inhibit but can instead stimulate autophagy.

Accordingly, scientists have found that both caffeinated and decaffeinated coffee can activate autophagy in muscles, liver, heart, and other vital organs (Pietrocola et al. 2014¹⁹).

Although coffee does not break a fast, additives often do so, such as

• Milk and skimmed milk
• Cream and creamer
• Soy and oat milk
• Sweeteners

A splash of almond milk may still move in a grey area. Nevertheless, even the thin nut milk technically breaks the fast.

Get more details in my ultimate guide to coffee and intermittent fasting.

Black Coffee

A cup of black coffee can contain 1-4 calories and tiny amounts of protein, fat, or trace elements.

Therefore, for most people, the nutrients in 1-2 cups of black coffee are not sufficient to influence their metabolism in a way that could break the fast (van Dam et al. 2004²⁰).

Since coffee can help suppress the appetite, it helps many people to hold on to fasting for longer.

Due to the stimulation of the hormone adrenaline, which prepares our body for stressful situations, massive amounts of coffee can influence intermittent fasting (Smits et al. 1986²¹).

Thus, glucose can enter the bloodstream without food intake (Sherwin et al. 1984²²).

As long as you do not drink more than 1-2 cups in a foreseeable period, coffee will not inhibit autophagy in this indirect way.

Due to the following properties, you can drink a cup of coffee at a time during intermittent fasting (Greenberg et al. 2012²³; Bagherniya et al. 2018²⁴; (Acheson et al. 1980²⁵; (Icken et al. 2017²⁶):

• Rich in antioxidants, which curb the appetite
• Induces and supports autophagy
• Increases metabolic rate
• Supports sustainable weight loss

Accordingly, espresso or black coffee is an ideal drink for in-between times, when appetite comes back. Nevertheless, it would help if you did not consume lots of it.

Bulletproof Coffee

Although Bulletproof Coffee is repeatedly declared to be safe for fasting, it is not.

The keto coffee may not cause insulin levels to rise, but it does supply the body with a lot of fat.

And as we know, the nutrient sensor AMPK reacts to fat. For this reason, Bulletproof Coffee affects autophagy.

Because the original Bulletproof Coffee contains only pure, high-quality fat but no other macronutrients, it does not increase insulin levels. You can find the recipe here:

Thus, you can stay in ketosis and burn fat.

Since it counteracts hunger, this coffee with MCT oil and butter helps beginners get accustomed to intermittent fasting.

If you only get along for 12 hours with black coffee but hold on fasting for 18 hours with a few teaspoons coconut oil, the fat addition is probably justifiable.

Nevertheless, after a few days of 16/8 intermittent fasting, you will no longer need these training wheels to prolong the fast.

Eventually, you want to burn body fat instead.

Can You Drink Bone Broth While Fasting?

Homemade bone broth from beef, pork, or chicken bones, not only tastes excellent but also has properties that help during fasting:

• It Supplies electrolytes
• Is easily digestible
• Contains natural fat that helps to absorb nutrients

But here is the crux of the matter: broth contains enough fat to activate AMPK and break a fast.

Therefore, bone broth is instead the first-class food for breaking a fast.

Since bone broth is packed with magnesium, potassium, calcium, and sodium, it can replenish the rinsed electrolytes.

Therefore, you can use bone broth as an electrolyte supply during fasting, e.g., during prolonged fasts over days or weeks. Consequently, it represents training wheels for intermittent fasting at best.

Can You Drink Pickle Juice When Fasting?

Just like bone broth, the water of sugar-free pickles has already helped many people during fasting. While bone broth is a comprehensive electrolyte dispenser, the cucumber water provides salt in particular.

Therefore you should drink it during intermittent or prolonged fasting if physical pain, such as headache, occurs.

Nevertheless, cucumber water should remain an aid for this particular purpose.

Does Drinking Apple Cider Vinegar Break a Fast?

Apple cider vinegar helps people digest healthy fats and integrate them into their diet more easily, as they boost nutrient absorption.

Furthermore, drinking apple vinegar supports intermittent fasting due to the following effects:

• Reduces blood sugar and promotes insulin sensitivity (White et al. 2007²⁷)
• Increases satiety and reduces the risk of overeating (Petsiou et al. 2014²⁸)
• Stimulates fat burning and helps lose weight (Li et al. 2013²⁹)
• Releases stomach and intestinal neutralizing hormones and ions (Petsiou et al. 2014³⁰)
• Works against heartburn and acid reflux

For these reasons, especially followers of low-carb diets such as the keto diet swear by apple cider vinegar.

Also, fasting beginners often use apple cider vinegar diluted with water. From a purely technical perspective, an apple cider vinegar drink could influence autophagy, but the tiny amounts of macronutrients are negligible in most cases (*).

Nevertheless, like broth, it is an aid for new fasting distances, and its properties make it a first-class drink that helps with ending a fast.

Can You Drink Juice During Intermittent Fasting?

Juices are often called natural products. But can one drink them, therefore, while intermittent fasting?

Fruit Juice

Compared to the consumption of whole foods, juices are way more harmful to health.

Juice leads to enormous blood sugar and insulin spikes since you remove the protective fiber with the flesh.

Precisely because the dietary fibers’ protective effect is missing, the fructose in fruit juices also bursts into the liver unchecked, causing insulin resistance and visceral fat in the long run.

For this reason, non-alcoholic fatty liver (NAFL) is much more common than fatty liver disease caused by alcohol (Angulo et al. 2002³¹).

Fruit juice not only breaks the fast but is not much better than a coke – no matter how “organic” it is. Anyone who seriously wants to lose weight must keep their hands off it – even during eating periods.

Celery Juice

Even though celery is on my low-carb food list, it remains a meal if you juice it.

Neither celery nor other vegetable juices are calorie-free, breaking the fast. Moreover, it is precisely sugar that makes up the essential energy component in celery and stimulates insulin (*).

Smoothies

Although smoothies contain some fiber due to mixing instead of juicing, they break an intermittent fast.

Compared to fruit juices, they are the lesser evil but still represent a meal.

Lemonade

Since it contains sugar, lemonade should not be drunk during intermittent fasting. Hence, you would have to reduce it to lemon water to be allowed during intermittent fasting.

But what is the verdict if lemonade contains zero-calorie sweeteners instead of sugar?

Can You Drink Diet Soda During Fasting?

The sweet taste is a particular topic in the context of intermittent fasting. On the one hand, it is already challenging to get rid of it. On the other hand, it additionally promotes cravings.

Most sugar-free sweeteners have zero proteins, carbohydrates, fat, or calories.

But many diet gurus forget that insulin release is not only stimulated by blood sugar.

However, this is what happens with sweeteners – many can increase insulin levels even more than the sugar in regular coke.

Diet Coke

One of the best-known sweeteners is aspartame, which has also been the basis for diet coke for decades.

Although calorie-free aspartame does not affect blood sugar levels, it increases insulin levels more than table sugar (Anton et al. 2010³²).

Therefore, the sweetener in diet coke prevents autophagy and fat burning.

With this in mind, it is probably no coincidence that people who consume vast quantities of diet drinks are overweight on average.

Coke Zero

Although Cola Zero varies in its composition, it always contains aspartame and acesulfame potassium.

Besides aspartame, the heat-stable sweetener acesulfame potassium in zero drinks increases insulin levels to the same extent as glucose, according to studies (Liang et al. 1987³³).

Therefore, coke zero is not suitable for autophagy and weight loss.

Furthermore, zero-calorie sweeteners stimulate cravings in the brain – a characteristic that does not fit intermittent fasting (Yang 2010³⁴).

Accordingly, researchers have found that zero and light drinks instead of regular soft drinks do not lead to the desired calorie reduction because of the increased appetite (Bellisle et al. 2007³⁵).

Green Coke

Ads sell stevia to us as the natural sweetener par excellence. Nevertheless, like table sugar from sugar beet, it is extracted from a plant and refined through chemical processes.

With this in mind, the sweetener in Green Cola suddenly no longer sounds that natural.

Additionally, the plant-based sweetener has further problems:

• Increases insulin levels (Anton et al. 2010³⁶)
• Alters the gut microbiome (Ruiz-Ojeda et al. 2019³⁷)

So the situation is exact. Stevia and Green Cola are not suitable for intermittent fasting.

Can You Drink Energy Drinks When Intermittent Fasting?

Regular energy drinks contain sugar. Thus, you cannot drink them during intermittent fasting.

Zero Calorie Energy Drinks

Such as coke zero, Red Bull Sugarfree, contains aspartame and acesulfame K.

Since sugar-free energy drinks cannot do without artificial sweeteners, they are unsuitable for fasting.

Bang Energy and Amino Acid Drinks

What’s the point of branched-chain amino acids (BCAAs) in fitness drinks? Growth!

For this reason, they stimulate the human body’s primary (muscle) growth pathway – mTOR.

Therefore, drinking Bang Energy or other amino acid drinks switches off the fasting mode and turns on growth in the human body.

As we already heard, mTOR is the primary nutrient sensor of our bodies that turns off autophagy. In short, Bang Energy and other amino acid drinks are anti-fasting beverages you want to avoid during intermittent fasting.

Gatorade and Powerade Zero

Even if the enrichment with electrolytes and vitamins sounds interesting for fasting, sugar-free sports drinks are not suitable for it at first sight.

For example, Gatorade and Powerade Zero contain sucralose, the sweetener in Splenda.

According to studies, just one pack of Splenda can be enough to wipe out 50 percent of healthy gut flora (Abou-Donia et al. 2008³⁸).

Moreover, sucralose increases the insulin level by about 20 percent, which breaks the fasting anyway (Pepino et al. 2013³⁹).

Do Protein Shakes Break a Fast?

Until the 1990s, scientists did not know protein strongly stimulates insulin (Nuttall et al. 1991⁴⁰).

For this reason, the first low-carb diets, such as the Atkins diet, were doomed to fail. The fact that the keto diet is based on this relatively new knowledge explains its popularity today.

Nevertheless, protein shakes still enjoy the image of a weight loss drink. However, there is hardly a drink that stimulates insulin, and the primary nutrient sensor mTOR like a protein shake with isolated whey protein.

Protein Shakes break a fast and directly inhibit autophagy, which aims to reduce harmful protein accumulations, such as in the brain (Li et al. 2017⁴¹).

Thus, autophagy counteracts our modern diseases characterized by too much protein and growth, ranging from dementia to cardiovascular diseases and cancer.

Can You Drink Alcohol During Fasting?

Because its effect is more intense on an empty stomach, you should not drink alcohol during intermittent fasting.

Moreover, alcohol is a source of calories that breaks a fast anyway.

Alcohol is also not a great idea during eating periods. Cocktails, mixed drinks, and especially beer are full of carbohydrates, stimulate insulin and appetite.

The exception is red wine, which can be drunk about glass size with dinner (Corrao et al. 2000⁴²).

When drunk with meals, red wine positively affects blood pressure, glucose, and insulin levels (Shai et al. 2007⁴³).

Drinking dry red wine like Pinot Noir can improve insulin sensitivity (Napoli et al. 2005⁴⁴).

Conclusion

If you want to skip the details above, here is the bottom line!

According to science, this is the list of what you can drink while intermittent fasting:

• Water
• Mineral Water
• Infused water with slices of lemon, orange, or cucumber
• Lemon water (single splash of lemon)
• Black coffee (no milk, sugar, or sweetener)
• Black decaffeinated coffee (see above)
• White tea (no milk, sugar, or sweetener)
• Green tea (see above)
• Oolong tea (see above)
• Black tea (see above)
• Herbal tea (check ingredients for sweeteners and fruits)
• Diluted apple cider vinegar (auxiliary agent)

What you can drink during intermittent fasting always depends on your goals. If your primary goal is weight loss, go with the list above.

If you aim at prolonged fasting for anti-aging and disease prevention, the opinions of researchers and experts differ.

Although numerous animal studies suggest that coffee and green tea support autophagy, the truth is that we don’t know for sure.

As there is no data on this in humans, many people restrict autophagy fasting to pure water fasting, where you may add only salt or mineral water if necessary.

However, green tea has activated autophagy in human cells, but these were previously implanted into mice (Prasanth et al. 2019⁴⁵).

Frequently Asked Questions (FAQ)

What can u drink during intermittent fasting?

You can drink water 💧, sparkling water, black coffee ☕ , and plain black or green tea 🍵 during intermittent fasting. Don’t add milk or sweeteners. For more options, see this guide.

Can I drink lemon water during intermittent fasting?

Yes, you can drink lemon water 🍋 during intermittent fasting. But make sure to keep it to a single squeeze of lemon juice.

Can you drink diet soda while intermittent fasting?

You cannot drink diet soda 🥤 during intermittent fasting because the sweeteners elevate insulin levels and stop autophagy and fat burning 🔥. Furthermore, they induce cravings.

What can I drink during my 16 hour fast?

You can drink plain water 💧, black coffee ☕ , and plain tea 🍵 during your 16 hours of fasting. For more options and details, check out this ultimate guide.

Studies

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⁵Catenacci VA, Pan Z, Ostendorf D, Brannon S, Gozansky WS, Mattson MP, Martin B, MacLean PS, Melanson EL, Troy Donahoo W. A randomized pilot study comparing zero-calorie alternate-day fasting to daily caloric restriction in adults with obesity. Obesity (Silver Spring). 2016 Sep;24(9):1874-83. doi: 10.1002/oby.21581. PubMed PMID: 27569118; PubMed Central PMCID: PMC5042570.

#6-12

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⁷Levine B, Klionsky DJ. Autophagy wins the 2016 Nobel Prize in Physiology or Medicine: Breakthroughs in baker’s yeast fuel advances in biomedical research. Proc Natl Acad Sci U S A. 2017 Jan 10;114(2):201-205. doi: 10.1073/pnas.1619876114. Epub 2016 Dec 30. PubMed PMID: 28039434; PubMed Central PMCID: PMC5240711.

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³⁶Anton SD, Martin CK, Han H, Coulon S, Cefalu WT, Geiselman P, Williamson DA. Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels. Appetite. 2010 Aug;55(1):37-43. doi: 10.1016/j.appet.2010.03.009. Epub 2010 Mar 18. PubMed PMID: 20303371; PubMed Central PMCID: PMC2900484.

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⁴⁵Prasanth MI, Sivamaruthi BS, Chaiyasut C, Tencomnao T. A Review of the Role of Green Tea (Camellia sinensis) in Antiphotoaging, Stress Resistance, Neuroprotection, and Autophagy. Nutrients. 2019 Feb 23;11(2). doi: 10.3390/nu11020474. Review. PubMed PMID: 30813433; PubMed Central PMCID: PMC6412948.