Green Tea Intermittent Fasting: Potential Effects and What to Know

If you enjoy the beverage, plain green tea is commonly considered compatible with many fasting routines as it contains very few calories. It also has no meaningful carbohydrates, so many people include it during a fasting window. The only catch is what you add. Adding sugar or milk adds calories and carbohydrates, which may matter depending on how you define your fast.

If your broader question is can you drink tea while fasting, plain unsweetened tea is usually one of the simplest options. Green tea, black tea, and many herbal teas are naturally very low in calories, as long as you skip sugar, honey, milk, and other add-ins.

Intermittent fasting means cycling between set eating periods and fasting periods, such as a 16-hour fast with an 8-hour eating window (16:8). During these fasting hours, the goal is to skip food, but you can still sip something with no or a negligible amount of calories. Plain green tea often fits this approach because it has almost none, which is exactly why so many people reach for it.

If you’re new to intermittent fasting or simply fine-tuning habits you already have, this guide will help you understand how green tea may fit into an intermittent fasting routine. The details matter more than they seem: some add-ins can add calories or carbohydrates during a fasting window, while a plain cup may make fasting hours feel more manageable for some people. 

To clear up the confusion, we’ll cover how green tea may fit into a fasting routine, what to skip during your fasting window, and how it may fit into your daily routine. The aim is clarity, not pressure—so you can choose what works for your own schedule.

Every fast is a personal experience. Your dietary preferences, body composition, and activity level all influence your fasting journey. It’s advisable to consult a healthcare provider before embarking on a fasting regimen.

Can I Drink Green Tea While Intermittent Fasting?

Plain green tea is commonly used during intermittent fasting as it contains very few calories. It also has no carbs (1), so it may fit into many fasting windows, depending on your fasting goals.

This is one reason some people choose green tea during fasting hours. Many people choose tea for fasting because it can feel more enjoyable than plain water while still staying very low in calories.

Keep it simple. During your fasting hours, skip sugar, honey, syrups, and milk. A small squeeze of lemon adds very few calories, but anything that adds meaningful calories may affect your fasting window. As a general guide, keep what you sip very low in calories.

Green tea also fits into a wider list of intermittent fasting drinks. During fasting hours, many people stick with plain water, sparkling water, black coffee, plain tea, or unsweetened herbal tea. The goal is to keep drinks calorie-free or very low in calories, depending on how strict your fasting approach is.

Once you’ve got the basics down, adding green tea can be simple. Let’s look at why it works, starting with the numbers.

Green Tea Nutrition Facts

Green tea is very low in calories, which is why many people use it during fasting. A standard 8-ounce brewed cup has just a trace of calories and essentially no carbs, fat, or sugar.

An 8-ounce brewed cup of plain green tea contains roughly (1):

• Calories: about 2
• Carbs: 0g
• Fat: 0g
• Added sugars: 0g
• Protein: around 0.5g
• Sodium: a couple of milligrams

With numbers this low, plain green tea is commonly considered to be compatible with many fasting routines. That’s why it makes most lists of low-calorie drinks used during fasting. The only thing that changes this is what you stir in.

As a rule of thumb, enjoy your green tea as-is and save sweeteners and milk for your eating window. With the nutrition clear, let’s look at what green tea may offer while you fast.

How Green Tea May Fit into Fasting

Green tea may fit into a fasting routine as it’s low in calories and contributes to fluid intake. These effects aren’t guaranteed and can vary from person to person, but many people find that tea makes fasting hours feel more manageable.

First, a quick refresher. Intermittent fasting means going without food for set periods each day or week. For some people, particularly early on, fasting can bring a few uncomfortable moments, such as (2):

• Tiredness
• Trouble settling into sleep
• Hunger
• An unsettled stomach
• Head discomfort

Even shorter fasting windows can feel challenging at first, and a warm drink may feel comforting for some people. Here’s how.

May Contribute to Fluid Intake

Green tea adds to your daily fluid intake, which matters during a fast. As it’s very low in calories, it can be one low-calorie drink option during fasting hours.

Drinking enough fluids is part of a balanced daily routine. Pair your green tea with plenty of water to support your hydration—no extra calories added.

May Help Some People Handle Hunger

Some people find that warm drinks make hunger feel easier to manage during fasting hours. Early in a fast, cravings can feel loud, and a warm drink often helps quiet them (3).

For many people, sipping plain, sugar-free tea is a common way to ride out hunger waves. It won’t replace a meal, but it gives you something soothing to sip while you wait for your eating window.

Contains Caffeine and L-Theanine

Green tea contains caffeine and L-theanine, compounds that are often discussed in relation to alertness and focus. Together, these are often linked to how alert or focused some people feel (4).

Researchers have studied green tea catechins, including EGCG, in relation to several biological processes (5):

• Anti-inflammatory
• Antioxidant
• Metabolic benefits

However, this doesn’t mean that green tea produces guaranteed health effects during fasting.

Some research has explored green tea compounds and brain-related markers, but more human research is required before any firm conclusions can be drawn (6). Some people feel less alert during fasting, and caffeine-containing drinks may affect alertness differently from person to person.

Consider Timing Because Green Tea Contains Caffeine

Green tea can fit into your evening, but timing matters as it contains caffeine. Because green tea contains caffeine, timing may matter if you are sensitive to it. If green tea’s caffeine keeps you up, try sipping it earlier in the day and switching to a caffeine-free herbal option at night.

Green Tea and Weight-Management Routines

Green tea may fit into a weight-management routine as a low-calorie drink option, but it isn’t a standalone solution. In one review, green tea compounds containing catechins or caffeine were associated with small changes in body-weight-related outcomes in some studies (7). Results can vary, and tea on its own isn’t a quick fix.

Green tea should not be treated as a standalone strategy. Think of it as a low-calorie drink option that sits alongside other routines, such as:

• Moving your body regularly
• Eating balanced, satisfying meals
• Getting consistent rest
• Staying well hydrated

Treat green tea as one small habit within a broader routine, not as a quick fix. It can be included in combination with steady habits such as movement, balanced meals, rest, and hydration. Green tea can be part of that mix—just not the magic ingredient.

Does Black Tea Break a Fast?

Plain black tea is commonly considered compatible with many fasting routines as it’s very low in calories. Like green tea, it’s naturally very low in calories and carbs (8), so many people include plain black tea during fasting hours, as long as it’s kept plain.

The same rule applies: skip the sugar, honey, and milk during your fasting window. Milk adds calories and carbohydrates, which may matter depending on your fasting goals. If you take it black and unsweetened, you can include it as a low-calorie drink option. So whether you reach for green or black, plain tea can be a simple low-calorie option during fasting hours.

What about intermittent fasting coffee? Plain black coffee is commonly used during fasting because it contains very few calories. However, cream, milk, sugar, flavored syrups, and sweetened creamers can add calories and carbohydrates, so they’re usually better saved for your eating window.

Are There Downsides to Green Tea?

Green tea is popular, but there are a few things to consider before you make it your go-to. Many people drink brewed green tea in moderate amounts, but individual tolerance varies.

A few things to watch out for:

• Caffeine effects. Green tea contains caffeine, and for some people—particularly those who are sensitive to it or drinking large amounts—this can lead to feelings of jitteriness, worry, or trouble settling into sleep (9).
• Tooth staining. Tea contains tannins that can stain teeth over time. Moderate intake and regular oral hygiene may help limit staining (10).
• Concentrated extracts. Green tea extracts, which are far more concentrated than a regular cup, have been linked to general unwanted effects in some cases (11). If you notice any unusual discomfort while using concentrated extracts, you should stop and check in with a healthcare provider.

Some people include a few cups of brewed green tea in their day, while others may prefer less due to caffeine sensitivity. Start with an amount that feels comfortable for you and adjust based on your response.

FAQs

• Does green tea spike insulin?

Plain green tea contains very few calories and carbohydrates, so it’s not usually expected to meaningfully affect insulin on its own. Some research has explored green tea consumption in relation to glycemic markers, but individual responses vary and more context is needed (12).

• Does green tea flush out sugar?

No, no food or drink can “flush out” sugar. After you eat, your body manages blood sugar through normal metabolic processes. Green tea doesn’t speed this up.

• Does green tea block carbs?

Possibly. Some research has suggested that some extracted green tea compounds have been studied in relation to digestion and nutrient absorption in the digestive tract, at least in animals (13). It’s not clear whether regular brewed green tea works the same way, and individual responses can vary.

• What tea won’t break intermittent fasting?

Plain, unsweetened teas are commonly used during fasting as they contain very few calories. These include green tea, black tea, and herbal options such as peppermint, ginger, or chamomile. Be cautious with fruit teas, which can carry added sugars, and remember that sweeteners, milk, or other add-ins may add calories or carbohydrates.

• Does black tea break a fast?

No, plain black tea doesn’t break a fast. It’s incredibly low in calories and carbs, so just keep it free of sugar, honey, and milk during your fasting window.

Every fast is a personal experience. Your dietary preferences, body composition, and activity level all influence your fasting journey. It’s advisable to consult a healthcare provider before embarking on a fasting regimen.

The Bottom Line

Plain green tea can fit into many intermittent fasting routines as it’s very low in calories. Plain green tea is naturally very low in calories and carbs, so many people consider it compatible with a fasting window—as long as you skip the sugar, honey, and milk.

Green tea contributes to fluid intake, and some people find warm, unsweetened drinks helpful during fasting hours. It can also be used as a low-calorie drink within a broader routine, alongside movement, balanced meals, and rest. If you’d like to try it, keep it simple: brew a plain cup, leave it unsweetened, and see how it feels for you.