When you fast for 16 hours or more, it is common to start wondering if there is anything that you can consume during your fasting window. In this blog post, I go over what breaks a fast, including drinks, supplements, and foods.
What Breaks a Fast? At-A-Glance
- Coffee & Tea Add-ins: Anything other than water has the potential to impact your fast. If you enjoy something in your coffee or tea, here is a list of items that will have the least impact:
- ADD THIS: Cream (heavy or coconut), MCT oil, Coconut oil, Butter, Half-and-half, Full-fat milk, Stevia or Monk Fruit, Spices
- NOT THIS: Low-fat (skim) milk, Nut milk, Sugar, Artificial sweeteners (Equal, Splenda, Sweet’N Low), Honey, Agave
- Supplements & Supplemental Foods: Some supplements are best absorbed when taken with food. Others have the potential to break your fast but provide benefits. Here are some general guidelines:
- BEST TAKEN WITH FOOD: Whey protein, Protein powders, BCAAs, Fat-soluble vitamins (A, D, E, & K), Multivitamins, Omega-3s, Probiotics, Bone broth, Fiber supplements
- OK TO TAKE DURING YOUR FAST: Water-soluble vitamins (B & C), Electrolytes, Apple cider vinegar
What Breaks a Fast? Infographic
What Breaks a Fast? A Full Guide to Drinks, Supplements, and Foods [Video]
In this video, you’ll learn…
- What breaks a fast?
- How to decide if it’s worth it to consume something that does break your fast.
- Further clarifications (Ex. what can be added to coffee and which supplements can be eating while fasting).
Wouldn’t Anything Break a Fast?
In the strictest sense, a fast is performed without calories. No food, drink, or substances that challenge your metabolism. However, adhering to inflexible rules like that can leave you feeling uncomfortable and hungry, which jeopardizes your long-term fasting success. Therefore, we will look for foods or beverages that you can consume while fasting and still reap the benefits of the fast.
With no calories and no nutrients to influence your metabolism, water is safe to drink at any time during your day. This includes tap water and unsweetened mineral water or bubbly water, such as carbonated water, sparkling water, club soda, or seltzer. These water options mix things up a bit and add a touch of variety and satisfaction to your fast.
Adding lemon to your water would add a few calories. However, it is doubtful that a small amount of lemon juice is enough to destroy the benefits gained over hours of fasting. Water sweetened with a non-caloric sweetener is a different story.
Natural and Artificial Sweeteners
There is evidence that non-caloric sweeteners are not the metabolic free ride they are made out to be. Some of them have a glycemic index, which means that they cause a rise in your blood sugar. Studies have linked these substances to altered gut health, glucose intolerance, and insulin resistance, which are all issues that can impact your ability to lose weight (1) (2).
It can be argued that not all non-caloric sweeteners are created equal. I would concur that stevia, monk fruit, and others that are derived from natural substances are better options than artificial sweeteners, like Splenda, Equal, and Sweet-n-Low. However, beyond the debate over their health value, there is one overarching reason why I recommend reducing or eliminating all sugar substitutes from your diet.
That reason is that their intense sweetness keeps your addiction to sweets alive. Sugar-free foods and beverages are still sweet. If you continually consume them, you constantly feed your sweet tooth, making it much easier to slip back into poor eating habits.
Coffee and Tea
Coffee and tea may start your “metabolic clock” but are generally accepted as okay to consume during a fast.
Your “metabolic clock” can be thought of as the prime time you have to utilize calories. An important activator of your metabolic clock is your first bite or sip of food or drink for the day. So, your body can use and process food better at the beginning of your eating window than at the end.
With this understanding, you could argue that the non-caloric nutrients you ingest when you drink a cup of coffee or tea break your fast and should be avoided. However, many fasting studies have allowed participants to consume non-caloric drinks like coffee and tea. The consumption of these drinks did not hinder their results in a significant way.
Cream and Other Fat Calories (Bulletproof Coffee)
If a plain cup of black coffee or tea doesn’t thrill you, you’re likely looking to stir in a bit of flavor. One way to do that is by adding a form of fat, such as cream or fats that turn coffee into a keto or bulletproof coffee such as MCT oil, butter, or coconut oil.
Foods that consist primarily of fat have little impact on your blood sugar and insulin level, so consuming fat calories during your fasting period will not knock your body out of fat-burning mode.
That’s a good thing and the reason why most people find that they can enjoy a bit of cream or similar items in their coffee or tea without noticeable consequences. However, fat has calories, and calories are energy. Your body will use those easily accessed calories before returning to the less accessible calories stored in your fat cells.
If you have three cups of coffee throughout the morning and add cream to each of those cups, you are providing your body with a consistent energy source instead of burning it from your body stores.
Milk (including plant-based milk such as hemp or almond milk) contains a mix of fat, protein, and carbohydrates, which gives it more potential to break a fast. If milk is your preferred add-in, you’ll be happiest with your results if you use full-fat milk or go for half and half, which is a mix of cream and milk.
If you would like some flavor in your coffee or tea but want to avoid calories, you may want to consider adding a spice. This takes some experimenting to discover what tastes good to you, but feel free to add a shake of turmeric, cinnamon, nutmeg, or other favorites to your morning brew.
Supplements & Supplemental Foods
Let’s shift away from drinks and take a look at how supplements and supplemental foods affect your fast. As a general rule, the best advice on timing your supplement intake is “when in doubt, take it with food.” However, this simple instruction invites a lot of “buts, what ifs…”
“But, what if I fast for longer than a day?”
“But, what if I need to take the supplement with a workout, before bed, or first thing in the morning?”
With so many supplements on the market, it would be impossible to review all of them. However, we can group supplements together and consider how your body uses them to make educated decisions about whether to take the supplement during your eating or fasting window.
To build muscle, you need protein. If you work out during your eating window, protein is provided through your diet. However, what if you work out during your fasting window? Would taking a supplement such as whey protein or BCAAs (branched-chain amino acids) break your fast? The answer is yes, but the full question to contemplate is whether that temporary break is defeating your goal.
When you fast, specific growth pathways, such as IGF-1 and mTOR, are deactivated. This is not necessarily a bad thing because these pathways must be deactivated for autophagy to happen. If your goal is to gain muscle, you want these growth pathways to be active.
One way to do that is to take in amino acids. The decision of whether or not to take a protein-based supplement during your fast comes down to how you answer this question: “Will this temporary disruption of my fast be worth the muscle growth that I stand to gain?”
Vitamins, Omega-3s, Electrolytes, and Probiotics
There are many types of supplements that you can take to support your general health. Most will be best taken with food, but if you are doing an extended fast or prefer taking them in the morning or before bed, they will still provide benefits. Let’s consider a few of the more common ones.
Multivitamins and other fat-soluble vitamin supplements are best taken with food to support the absorption of the fat-soluble vitamins, which are vitamins A, D, E, and K. I would say the same for Omega-3 fatty acids, which are often consumed in capsule or liquid form, much like a vitamin.
On the other hand, water-soluble vitamin supplements, which include vitamins B and C, as well as electrolytes, are okay to take any time of day, whether during your fasting window or not. Your body naturally loses electrolytes when fasting, so you’ll need to replenish them to feel your best and avoid common issues like muscle cramps, headaches, and sleep problems.
Look for an electrolyte supplement that contains potassium, magnesium, sodium, and chloride, and take it daily in a fasted or fed state.
Probiotics are a bit tricky to figure out. They contain live microorganisms that support the beneficial bacteria living in your gut. To get down to your gut, the microorganisms must survive a long journey through your digestive tract. Whether they survive better traveling with or without food is debated, and research findings are inconclusive. So, this is one of those times that our adage, when in doubt, take it with food comes in handy.
Bone broth is rich in amino acids, which are the building blocks of protein. Much like the protein supplements, it can disrupt your fast. However, this is another instance where the benefits might outweigh the drawbacks.
If you are just getting started and feeling fatigued or hungry, bone broth can support you as you work toward becoming more comfortable with fasting. If you are doing an extended fast, you may find that bone broth helps you control hunger and feel good while preserving the overall benefits of the fast.
It may also help protect muscle mass during a prolonged fast, thanks to its high protein content.
Apple Cider Vinegar
Because of its many benefits and the fact that it is free of calories, apple cider vinegar is acceptable to take during your fasting window or right before a meal. Some people also claim that taking it during their fast helps control hunger.
One note of caution: it is not the most pleasant-tasting substance, and its acidic nature can damage your throat or teeth if taken straight. By diluting a couple of tablespoons in a glass of water with lemon, you’ll help the “medicine” go down.
I hope this information helps you feel your best during your fast. Thank you for reading and have a wonderful week!
(1) Suez, Jotham, et al. “Non-caloric artificial sweeteners and the microbiome: findings and challenges.” Gut microbes 6.2 (2015): 149-155.
(2) Ruiz-Ojeda, Francisco Javier, et al. “Effects of sweeteners on the gut microbiota: a review of experimental studies and clinical trials.” Advances in Nutrition 10.suppl_1 (2019): S31-S48.
(3) Mitrou, Panayota, et al. “Vinegar consumption increases insulin-stimulated glucose uptake by the forearm muscle in humans with type 2 diabetes.” Journal of diabetes research 2015 (2015).
(4) White, Andrea M., and Carol S. Johnston. “Vinegar ingestion at bedtime moderates waking glucose concentrations in adults with well-controlled type 2 diabetes.” Diabetes care 30.11 (2007): 2814-2815.