What Can I Drink During a Fast?

What can I drink during a fast? Options such as water, black coffee, and herbal teas can help keep you hydrated and may even curb hunger, contributing to a smoother fasting experience.

Knowing which beverages will support hydration and which ones may kick you out of ketosis is essential to reap the impressive health benefits of fasting. 

Explore the best choices to incorporate into your fasting routine to stay hydrated and energized during periods of caloric restriction. 

Can liquids break a fast?

Whether a liquid can break a fast depends on its contents and the type of fasting approach you’re following.

During intermittent fasting, beverages with few calories, including black coffee, green tea, and diluted apple cider vinegar, typically don’t break your fast and may even support your health goals by promoting hydration and focus.

However, drinks containing sugar or significant amounts of calories can trigger metabolic responses that effectively end the fasting period.

In contrast, other fasting variations, such as time-restricted eating, may allow small amounts of healthy fats, such as coconut oil, to be included without fully interrupting the fasting state.

Ultimately, the impact of liquids on the metabolic fasting state depends on their ingredients and how they align with your goals, such as managing insulin resistance or supporting a flexible fasting lifestyle.

Watch the video below to learn which drinks are acceptable during a fast.

Water fasting vs. dry fasting

While water fasting and dry fasting are two approaches that involve caloric restriction, they differ significantly in how fluids are incorporated.

Understanding the differences between these two practices can help you make informed decisions based on your health objectives.

Here are the commonalities and differences between dry and water fasting.

Water fasting

Water fasting allows the inclusion of zero-calorie beverages but excludes all other foods and fluids. This offers a fasting plan that supports hydration while maintaining a metabolic fasting state. 

This method is commonly used to support fat burning and may help promote balanced blood sugar levels when paired with a consistent fasting schedule.

Furthermore, evidence published in Nutrition Reviews revealed that sustained water fasting “for 5 to 20 days produces potent increases in circulating ketones, and mild to moderate weight loss of 2 to 10 percent.”¹

Because water fasting incorporates hydrating beverages, it’s often considered more sustainable over longer periods than dry fasting.

However, it still requires caution, especially for individuals with a history of eating disorders, as prolonged calorie restriction may lead to adverse effects.

Dry fasting

Dry fasting protocols eliminate both food and all liquids, making it a significantly more challenging approach that is typically practiced only in the short term.

However, a study published in Metabolism Open found that dry fasting may positively impact inflammation markers in people with higher body mass index (BMI). The findings suggest that this form of fasting may assist in lowering levels of inflammation linked to obesity.²

While advocates of dry fasting claim that it may accelerate fat breakdown, the absence of fluid intake can increase strain on the body and limit the duration safely tolerated.

Many consider dry fasting much stricter than water fasting because it eliminates all liquids and even small amounts of food, unlike dirty fasting, which allows minimal intake of certain foods and beverages.

While dry fasting may help trigger and maintain ketosis, it can have health consequences if not done properly or followed by inconsistent refeeding, especially with nutrient-poor or overly processed foods. 

What can you drink during a fast?

Choosing the right beverages is key to staying hydrated and supporting your fasting goals.

Drinking water is the most essential option, as it assists in hydration and can curb hunger naturally. Sparkling water is also permitted, as long as it’s free of sweeteners or added calories.

Black coffee is commonly consumed during fasting windows because it contains no calories and may promote alertness.

Variations, such as bulletproof coffee, made with black coffee and small amounts of healthy fats such as grass-fed butter and medium-chain triglycerides (MCT) oil, can also be consumed.

Similarly, black and green tea, as well as unsweetened herbal tea varieties, provide health-promoting antioxidants while keeping your body in a metabolic fasting state. 

You might see Polydextrose Keto listed in flavored waters or diet drinks. While technically low in carbs, it’s best to avoid it during fasting to maintain insulin stability.

Additionally, a diluted apple cider vinegar drink can be included to support digestive health and appetite control. 

These beverages contain no or very few calories and won’t interfere with the health benefits of intermittent fasting. 

However, it’s crucial to avoid beverages with added sugars, creamers, or artificial flavors, as these can break a fast and counteract the metabolic benefits of caloric restriction. 

Drinks to avoid while fasting

During a fasting window, it’s vital to avoid drinks containing sugar, preservatives, or milk. 

These ingredients can trigger an insulin response, which interferes with fat burning and breaks a fast, making it harder to lose weight, support metabolic health, and maintain steady energy levels. 

“Even products labeled ‘diet’ or those containing zero calories can contain artificial sweeteners,” explains Dr. Berg. “These might not have calories, but they can trigger cravings, affect your metabolism, and make it harder to stay consistent when intermittent fasting.”

Flavored coffees, energy drinks, and smoothies should also be avoided, as they typically contain hidden sugars or excessive amounts of calories unsuitable for maintaining a fast.

Additionally, alcohol should be avoided, as it triggers hormonal and metabolic changes that interfere with fat-burning, increase the risk of dehydration, and may disrupt digestion after the fasting period. 

How much should you drink while fasting?

According to research published in Global Advances in Health and Medicine, it’s recommended to consume around 2 to 3 liters of fluids each day while water fasting, with a focus on mineral-rich water.³

This helps your body stay hydrated and supports the balance of essential minerals, including sodium, potassium, and magnesium.

It’s equally important to balance hydration during your eating window by consuming nutrient-dense foods that naturally contain water and electrolytes. These include low-carb berries, leafy green vegetables, dairy products, kefir, and bone broth.

In addition, exercise and heat exposure can increase your body’s need for hydration, and it’s important to pay attention to thirst cues and replace fluids lost through sweat.

FAQ

Sources

1. https://pubmed.ncbi.nlm.nih.gov/37377031/ ?
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC10918425/ ?
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC8369953/ ?