Fasting has become an increasingly popular way to lose weight, improve health, and simplify eating habits. But there is still a lot of confusion around what you can and cannot eat or drink while fasting. Can you really eat anything at all?
What is fasting?
Fasting simply means going without food and drink for a period of time. There are several different types of fasting including intermittent fasting, alternate day fasting, and extended fasts lasting multiple days or weeks.
With intermittent fasting, the most popular approach, you restrict eating to a specific window of time each day, usually from 8-10 hours. The remaining 14-16 hours become your fasting window when you consume nothing except water, coffee, tea, and other non-caloric beverages.
Alternate day fasting involves a 24-hour fast followed by a 24-hour period where you can eat normally. Other approaches like the 5:2 diet involve severe calorie restriction for 2 days per week and normal eating the other 5 days.
General guidelines on what you can eat and drink while fasting
During the fasting window, the general rule is that you cannot consume any calories whatsoever. The key is that anything you eat or drink should have minimal effects on your blood sugar, insulin levels, and other metabolic factors. Here are some general guidelines on what you can and cannot consume during a fast:
- Allowed: water, black coffee, unsweetened tea, carbonated water, apple cider vinegar drinks
- Not allowed: milk, juice, sugary drinks, protein shakes, alcohol
- Not allowed: any type of solid food including fruits, vegetables, nuts, seeds, grains, etc.
Some people choose to follow a “clean fast” where they allow only water, while others are more flexible and allow zero calorie beverages. But no food or supplements with calories are allowed during the fasting period. Even chewing gum could be considered breaking your fast in some cases.
What breaks a fast?
Here are some examples of things that would break your fast and require you to restart the clock:
- Consuming any type of solid food
- Having caloric drinks like juice, soda, or alcohol
- Adding cream, sugar, or milk to your coffee or tea
- Taking supplements or medications with calories
- Chewing gum with artificial sweeteners
Even something as simple as 10 calories from cream in your coffee is enough to break your fast. This requires metabolic switching back to a fed state and restarts the benefits you are trying to achieve with fasting.
Specific foods and drinks to avoid while fasting
To safely remain in a fasted state, here are some specific foods, drinks, and supplements you should avoid:
- Fruit or vegetable juice – While nutrient-dense, these are high in sugar and calories.
- Diet soda or zero calorie drinks – Artificial sweeteners may stimulate appetite or insulin secretion.
- Coffee creamers – Even “zero calorie” creamers have a minimal amount of calories that can impact ketosis.
- Bone broth – While low in calories, bone broth can stimulate digestion and may not align with goals of fasting.
- Essential amino acid supplements – Amino acid supplements contain calories and protein that affect metabolism.
- Almond milk – Despite being plant-based, almond milk has calories that could technically break your fast.
- Gum or breath mints – Most chewing gum contains artificial sweeteners that could trigger cravings.
What can you eat and drink while fasting?
Given all the restrictions around fasting, you may wonder – can you eat or drink anything at all? Here are the best options:
- Water – Stay well hydrated by drinking water throughout your fasting period.
- Black coffee – Enjoy plain coffee without any sweeteners, milk or cream added.
- Tea – Green tea, black tea, and herbal teas are great for fasting.
- Apple cider vinegar – Some dilute apple cider vinegar in water for health benefits.
- Sparkling water – Carbonated drinks like soda water won’t affect your fast.
- Broth – Bone broth is sometimes allowed during more flexible fasts.
- Lemon water – This provides flavor without calories or sweeteners.
In general, stick to non-caloric beverages without sweeteners. Water is always your best bet. Focus on hydration and resist the temptation to snack on anything with calories or artificial ingredients.
Does fasting allow special foods?
No – there are no special exceptions that allow you to consume certain foods or drinks and remain in a fasted state. The key is avoiding anything with calories. Some people believe that certain very low calorie foods like broth or jello may be permitted, but this is controversial. To be on the safe side, do not consume these.
Don’t try to find loopholes or special foods that you hope won’t break your fast. Even minimal calories from special products can trigger an insulin response and disrupt some of the intended benefits of fasting. Play it safe by only consuming plain water, black coffee, and tea.
Will diet soda or other zero calorie drinks break my fast?
Opinions differ on whether zero calorie beverages technically “break” a fast. In theory, diet soda will not inhibit fat burning or cause insulin spikes. But even without direct effects on metabolism, research shows that artificial sweeteners may trigger appetite and cravings. The taste sensation of sweetness, even without calories, may also activate certain digestive processes.
For these reasons, plain water is the best and safest choice. But an occasional diet soda, energy drink, or coffee with artificial sweeteners is unlikely to negate the overall benefits of intermittent fasting. Just be cautious about relying on them too frequently during your fast.
Can I drink coffee with cream during a fast?
Coffee with significant amounts of cream, milk, or other caloric add-ins should be avoided during fasting windows. Just a splash of cream or milk in your coffee might be 5-10 calories. Some very strict interpretations consider even 10 calories enough to break your fast.
However, a small amount of milk, under 50 calories, will generate a minimal insulin response. If your main goal is fat burning, this small amount of cream or milk in coffee a couple times a day will probably not make a major difference in the overall benefits of intermittent fasting.
What about bone broth or miso soup while fasting?
Drinks like bone broth and miso soup occupy a gray area. They contain minimal calories, protein, and carbohydrates, but still involve some digestion and metabolic processing when consumed. Experts disagree on whether the small amounts of amino acids and minerals are enough to technically break a fasted state.
For strictest adherence to fasting, avoid any broths or soups. But during more flexible fasting protocols, a small amount of these drinks can provide sorely needed sodium, potassium, and other nutrients without significantly disrupting your goals.
Can I use zero calorie sweeteners in my tea and coffee?
Artificial sweeteners such as aspartame, sucralose, or stevia will not directly affect your insulin levels and ability to stay in a fasted state. However, some research shows that the taste of sweetness can trigger the release of digestive enzymes and hormones like insulin even without calories present. Artificial sweeteners may also increase hunger.
To be safe, avoid adding any type of zero calorie sweeteners to your drinks during fasting periods. Plain tea or coffee with no sweeteners is the surest way to remain in a fasted state and experience the full benefits.
Will chewing gum break my fast?
Technically, chewing gum should not break a fast since it contains zero net calories and is not actually swallowed. However, many types of gum contain artificial sweeteners which, as mentioned earlier, could stimulate appetite or cravings that make fasting more difficult.
There is also some evidence that the action of chewing itself can trigger digestive processes and hunger hormones like ghrelin even in the absence of calories entering the stomach. For these reasons, gum is probably best avoided during your fasting periods.
Can I drink alcohol while fasting?
Alcoholic drinks would definitely break a fast due to the calorie content. A 12oz beer alone contains 150 calories, instantly taking you out of a fasted state. Hard liquor, wine, and mixed drinks all have calories that will disrupt your fast.
There is also evidence that alcohol triggers hunger hormones and cravings for unhealthy foods. So not only does alcohol contain empty calories, but it can sabotage your self-control and motivation for fasting overall. It is best avoided during both fasting and non-fasting periods.
Do low calorie supplements like BCAAs break a fast?
Branched chain amino acids (BCAAs) and other essential amino acid formulations contain protein and calories that would technically break your fast. Just 5-10 grams of these supplements equates to 20-40 calories entering your system along with amino acids that stimulate digestion and metabolism.
An occasional low dose of aminos before exercise may be alright, but in general these supplements should be avoided during fasting periods. Plain water does not provide any amino acids, so be sure you eat sufficient protein during your non-fasting times.
Can you have broth during a water fast?
For a pure water fast allowing only water and no food intake, consuming broth would go against the spirit and purpose of the fast. Even the small amounts of calories and amino acids from broth require some metabolic processing that would technically break ketosis.
However, during longer fasts of 3-5 days, having an occasional cup of broth may provide some needed sodium, nutrients, and comfort to help you stick with the regimen. Whether this minimally impacts your results depends on your goals with water fasting.
Will diet soda kick me out of ketosis?
One of the concerns around diet soda is that while the sweeteners themselves may be zero calorie, they can theoretically spike insulin and knock you out of ketosis. However, studies show that even sodas sweetened with aspartame have minimal effect on insulin levels.
Diet sodas also do not provide carbs that would impact ketone levels or fat burning. An occasional diet soda instead of water likely will not affect ketosis or fat loss. But sticking mainly to water rather than artificially sweetened beverages is encouraged for overall health.
Can you drink coffee while fasting for blood tests?
Yes, black coffee is perfectly fine to consume while fasting for blood tests. Plain coffee has no calories and minimal effects on most blood markers. Avoid adding cream or sugar since calories could impact some fasting blood test results.
Coffee may elevate bilirubin levels, but this marker alone is not used to diagnose major health conditions. Moderate coffee intake is allowed and will not interfere with commonly ordered blood tests.
Will lemon water break your fast?
Lemon water is perfectly acceptable on fasts. Although lemon juice contains calories, the amount in a typical glass of lemon water is very low – around 5-10 calories at most. There is no consensus about whether such a tiny calorie intake would break a fast.
Lemon provides health benefits like vitamin C and flavonoids. The small amount of citric acid may actually support metabolism. Overall there is little downside to including lemon water in your fasting regimen.
Can you put stevia in coffee while fasting?
Pure stevia extract has zero calories or carbohydrates that would directly disrupt your fasted state. However, some experts caution against using any artificial sweeteners during fasting periods. Tasting something sweet can trigger hunger signals, make fasting more difficult, and undermine some of the intended hormonal benefits.
A minor amount of stevia in your coffee once or twice a day is unlikely to negate your fasting regimen. But avoiding sweet flavors altogether and sticking to plain black coffee is the most purist approach during your fasts.
Conclusion
In summary, water, black coffee, and plain tea without any caloric add-ins are universally accepted on fasting protocols. Consumption of any type of solid food, calories from cream or milk, or sugary drinks will break your fast. Bone broth and diet soda occupy a gray area but are likely fine in moderation.
Aim to consume zero calories during your specified fasting windows. With some flexibility and commitment to the regimen, you can fast periodically throughout your week while still enjoying some of your favorite beverages.
| Beverage | Allowed During Fasting? |
|---|---|
| Water | Yes |
| Black coffee | Yes |
| Tea | Yes |
| Carbonated water | Yes |
| Apple cider vinegar drink | Yes |
| Bone broth | Maybe |
| Lemon water | Yes |
| Diet soda | Maybe |
| Coffee with cream | No |
| Fruit juice | No |
| Alcohol | No |
Following the general guidelines of avoiding all calories, sweeteners, and solid food during your fasting window will allow you to remain in a fasted state and receive the maximum benefits.
