Does Green Tea Break a Fast? The Effects of Green Tea on Intermittent Fasting

Does Green Tea Break a Fast?

Intermittent fasting has become an increasingly popular approach to weight loss and health in recent years. It involves alternating between periods of fasting and eating. Many people choose to drink teas and other calorie-free beverages during their fasting windows. But some wonder if drinking green tea in particular will break their fast.

Green tea contains a small number of calories and compounds that trigger mild metabolic effects. This has led to some debate regarding whether or not it is fasting-friendly. This article takes an in-depth look at the effects of green tea and provides guidance on whether or not you can drink it during a fast.

What is Intermittent Fasting?

Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. It doesn't specify which foods to eat but rather when to eat them.

There are several different IF protocols, including:

• 16/8 method: fasting for 16 hours per day, eating within an 8 hour window
• 5:2 diet: eating normally 5 days a week, fasting or restricting calories 2 days per week
• Alternate day fasting: fasting every other day
• One meal a day (OMAD): eating one meal per day

IF has been shown to aid weight loss, reduce inflammation, improve heart health, and support brain function, among other benefits (1, 2).

What Constitutes Breaking a Fast?

There are some differing opinions on what actually breaks a fast during intermittent fasting.

Technically, anything that contains calories breaks a fast. However, many concur that very low calorie beverages like tea, coffee, and diet soda can be consumed during fast periods without detrimental effects on health.

Drinking calorie-free beverages can also help curb appetite and make fasting periods more tolerable (3).

Here are some general guidelines on what breaks a fast:

• Food: Whole foods like fruits, vegetables, nuts, seeds, meat, etc. definitely break a fast.
• Beverages with calories: Fruit juice, alcohol, milk, and smoothies containing calorie-dense ingredients can all break a fast.
• Supplements: Some supplements like BCAAs or fat-soluble vitamins may induce a metabolic response. Avoid supplements during fasting periods.
• Extremely low-calorie drinks: Plain water, black coffee, unsweetened teas, and diet sodas/seltzers can likely be consumed without impacting fasts.

Does Green Tea Have Calories?

Plain, unsweetened green tea contains between 13 calories per 8 ounce (240 ml) cup. This minimal amount of calories is unlikely to impact your fast (4).

However, many pre-made bottled green teas contain added sugars and ingredients that can break your fast and add a significant number of calories. It's best to brew plain green tea at home and avoid sweetened bottled versions when fasting.

Other Components in Green Tea

Aside from calories, green tea contains certain plant compounds and caffeine that may technically break a fast due to their mild metabolic effects.

The main active components in green tea are (5):

• Caffeine: Stimulant that boosts metabolism by up to 11% and fat burning by up to 1029% (6, 7).
• Epigallocatechin gallate (EGCG): Most abundant antioxidant in green tea that mildly reduces fat absorption (8).
• L-theanine: Amino acid that may work synergistically with caffeine to further increase metabolism (9).

Although these compounds may slightly boost metabolism, it is unlikely their effects will fully break your fast or severely impact its potential benefits.

Does Green Tea Make You Burn More Calories?

Some studies show that green tea can mildly increase calorie burning, especially when paired with caffeine. However, its effects on metabolism are weaker compared to other components of tea.

This is what the research says:

• One study in 10 healthy men found that taking a green tea extract supplement increased calorie burning by 4% over 24 hours (10).
• Drinking a beverage with green tea catechins, caffeine, and calcium increased fat burning by 83 mg per hour, compared to 75 mg for caffeinated water (11).
• Yet, another study showed that a green tea extract enriched with a compound called epigallocatechin gallate (EGCG) had minimal effects on weight loss in overweight adults over 12 weeks (12).

While green tea likely won't produce major increases in metabolism for most people, its compounds may provide a slight boost when combined with fasting.

Does Green Tea Suppress Appetite?

Drinking green tea regularly has been associated with reductions in appetite and food intake, which can support weight loss.

For example, one analysis looked at 18 studies and found that drinking green tea was linked to significantly lower body weight and belly fat (13).

Research suggests EGCG and caffeine in green tea work together to increase levels of peptide hormones like leptin and GLP-1, which regulate appetite (14, 15).

Additionally, the act of drinking warm or hot beverages can help reduce appetite and increase feelings of satiety (16).

Therefore, enjoying unsweetened green tea during fasting windows may help suppress appetite for enhanced weight loss benefits.

Should You Drink Green Tea While Fasting?

Given its very low calorie content, green tea is unlikely to break your fast or severely impact its potential benefits.

However, to maximize fasting benefits, it may be best to limit caffeine intake from all sources, including green tea. Caffeine is metabolically active and could technically break ketosis for those following keto diets.

If you enjoy green tea and can tolerate the small amount of caffeine, there is no reason to avoid it during fasting windows.

It's best to keep intake below about 2 cups (500 ml) and avoid adding sugar, milk, or cream. Bottled green teas often have added sugars and should be avoided.

Additionally, taking green tea extract supplements may be more likely to break your fast, so reserve these for your eating periods.

Tips for Drinking Green Tea While Fasting

Here are some tips for drinking green tea during fasting windows:

• Brew plain green tea at home and avoid sweetened bottled varieties.
• Limit intake to 2 cups (500 ml) or less per day.
• Drink it unsweetened or add lemon, mint, or ginger for flavor.
• Try other low-calorie teas like black, white, rooibos, or herbal blends.
• Pair green tea with fasting-friendly herbs like parsley, cucumber, and lemon.

Other Fasting-Friendly Drink Options

Besides green tea, there are many beverage options to help get you through your fasting windows.

Here are some other fasting-friendly drinks:

• Water: Plain or sparkling water contains 0 calories and won't break your fast.
• Black coffee: With less than 5 calories per cup, black coffee is generally considered fasting-friendly.
• Tea: Unsweetened black, white, oolong, rooibos, and herbal teas can be enjoyed during fasts.
• Nut milk: Choose unsweetened varieties like unsweetened almond or coconut milk.
• Bone broth: This low-calorie soup can help provide electrolytes while fasting.

When in doubt, avoid creamers, sweeteners, juices, smoothies, and calorie-containing mixes.

Intermittent Fasting Teas

Some specific tea blends have gained popularity among intermittent fasting followers due to their purported metabolic and appetite-suppressing benefits:

1. Green Tea

Green tea contains caffeine and EGCG, which may provide a slight boost in calorie burning. It may also help reduce appetite when consumed before meals.

2. Black Tea

Like green tea, black tea contains plant compounds and caffeine that may slightly increase metabolism and fat burning.

3. Oolong Tea

Oolong is a Chinese tea that's partially fermented. It contains polyphenols that may help block fat absorption and increase fat metabolism.

4. Pu-erh Tea

A fermented Chinese tea, pu-erh is thought to suppress appetite through the release of certain digestive hormones.

5. Ginger Tea

Ginger tea may help curb hunger and boost satiety. Animal and human research links ginger to increased metabolism, reduced belly fat, and lower weight (17, 18).

6. Apple Cider Vinegar

Although not technically a tea, apple cider vinegar is a common addition to tea while fasting. Some research shows it may promote feelings of fullness (19).

Pairing your teas with fasting-friendly herbs like parsley, cucumber, mint, lemon, and ginger can further boost flavor and potential benefits.

Safety and Side Effects

For most people, drinking green tea during intermittent fasting is safe and provides additional health benefits. However, some things to keep in mind include:

• Caffeine sensitivity: Those who are sensitive or intolerant to caffeine may experience jitteriness, anxiety, headaches, or trouble sleeping.
• Pregnancy and breastfeeding: Pregnant or breastfeeding women should limit caffeine intake from all sources, including green tea.
• Medication interactions: The caffeine in green tea may interact with certain medications, including stimulants, blood thinners, chemotherapy drugs, and antibiotics.
• Health conditions: People with anxiety disorders, heart conditions, diabetes, or irritable bowel syndrome (IBS) should limit or avoid caffeine.

Additionally, drinking green tea in excess may cause side effects like upset stomach, constipation, and acid reflux in some people.

The Bottom Line

Based on the available evidence, drinking green tea during intermittent fasting is unlikely to break your fast or severely impact its potential benefits.

Green tea contains beneficial plant compounds and very few calories, making it a good low-calorie beverage choice while fasting.

However, to maximize fasting benefits, it's best to limit total caffeine intake and avoid adding sugar, milk, or cream. Stick to 12 cups (240500 ml) per day.

Pairing green tea with other healthy teas, brewing methods, herbs, and spices can add flavor and variety while you fast.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.