One of the most frequent inquiries I receive revolves around the question of whether a particular substance or action "breaks a fast." What people are really trying to ascertain is whether these things interfere with or negate the benefits of fasting, such as:
· Ketosis: Fasting is a rapid way to enter ketosis, a metabolic state known for its fat-burning properties, fat adaptation, and, in some cases, improved cognitive function by causing increase GABA release in the brain. Emerging findings suggest the metabolic switch from glucose to fatty acid-derived ketones represents an evolutionarily conserved trigger point that shifts metabolism from lipid/cholesterol synthesis and fat storage to mobilisation of fat through fatty acid oxidation and fatty-acid derived ketones, which serve to preserve muscle mass and function.
· Resting the Gut: The human digestive system exhibits daily rhythms in the secretion of saliva, gastric acids, digestive enzymes, and bile salts, as well as intestinal peristalsis, with reduced activity at night and increased activity in the morning. These rhythms lead to fluctuations in the gut's chemical environment, affecting the composition and function of the gut microbiome. With 70–80% of immune cells being present in the gut, there is an intricate interplay between the intestinal microbiota, the intestinal epithelial layer, and the local mucosal immune system.
· Weight Management: Fasting, by virtue of not consuming calories, encourages the body to utilise its existing fat stores for energy. Many individuals also find that fasting helps them manage their calorie intake effectively.
· Autophagy: This cellular process involves the removal of damaged components, sustaining cell function, and potentially slowing down the aging process. Fasting triggers autophagy, and ending the fast prematurely can halt this beneficial process. To fast for autophagy, this is a specific style of fasting that entails:
Approximately 17 hours of fasting
High fat
Low carb diet
Limited protein
Autophagy fasting would ideally be done one to three times a week.
Let's clarify something upfront: fasting isn't a diet; it's a lifestyle that adapts to your goals and various factors, both internal and external. Throughout human history, we've been adaptable omnivores, consuming a mix of plants, meats, organs, and seasonal fruits, berries, and nuts. But in today's world, food is always within arm's reach, just a few minutes away!
If you've discovered a fasting routine that aligns with your goals and yields the health results you desire, then, stick with it and ignore the following advice.
However, if you've been fasting and haven't achieved your desired outcomes, it's possible that something you're doing is impeding the potential benefits of intermittent fasting.
Regarding the idea that it only takes 10 calories to prevent autophagy, it's important to note that the relationship between calorie intake and autophagy is not precisely defined. The threshold for autophagy may vary from person to person and can depend on various factors, including your overall metabolism and insulin sensitivity. Some experts argue that a small number of calories, such as those in a cup of black coffee or tea, is unlikely to have a substantial impact on autophagy or fasting benefits for most people.
We need to give a little special mention to these two, black coffee and tea. These are two most consumed beverages (other than water) black coffee and black tea during intermittent fasting:
Myth: Black coffee doesn't break a fast.
Reality: Black coffee is often considered safe during intermittent fasting for many people depending on the volume they consume.
What is the verdict?
Fasting for metabolic health/weight loss– NO it will not break a fast
Fasting for Gut Rest – Yes it will interfere with gut rest
For longevity – Coffee is not likely to have an affect on longevity.
Some argue that coffee's metabolic response might disrupt a fast, but it can also enhance fat mobilisation, the polyphenols and fat burning, trigger autophagy, and reduce hunger. It typically contains very few calories (around 2 calories per 236mls), so if you are having five or more cups of coffee during your fast then this could be impactful. While there may be a minimal calorie content, it's unlikely to significantly impact your fast or prevent autophagy. However, it's essential to avoid adding sugars, cream, or other high-calorie additives, as these can break your fast. If you find adding MCT oils nearer the end of your fast helps you to get into ketosis better, then go for it.
Myth: Black tea doesn't break your fast.
Reality: Like black coffee, plain black tea is generally considered acceptable during intermittent fasting.
What is the verdict?
Fasting for metabolic health/weight loss – NO it will not break a fast
Fasting for Gut Rest – Yes it will interfere with gut rest
For longevity – Tea is not likely to have an affect on longevity.
Black Tea contains minimal calories, usually less than 2 calories per 236mls. Drinking plain black tea can help you stay hydrated and may also provide some health benefits. However, just like with coffee, avoid adding sugar or milk as they can add significant calories and disrupt your fast.
Ultimately, whether you choose to consume black coffee or black tea during intermittent fasting depends on your goals and personal preferences. If you're pursuing a more rigorous fasting approach, you might opt for plain water only. However, many people find that incorporating black coffee or tea can enhance their fasting experience without undermining their overall objectives. The key is to avoid calorie-rich additives and maintain consistency with your fasting schedule.
Let's explore some of the common questions about what does or doesn't break an intermittent fast:
Over the counter Medication: Your analgesics, cough, and cold remedies, antihistamines, essentially any OTC medication in tablet will not typically contain calories and therefore should be ok. Sugared lozenges, syrups and sugar free lozenges will contain calories and will break your fast.
Yerba Mate: Like tea, yerba mate is calorie-free and has positive effects on glucose tolerance, making it a good choice during fasting.
Bone Broth: Technically, it does break a fast, especially if it's gelatinous because it contains protein, fat and some carbohydrates. The nature of Bone Broth is that it will contain amino acids, which will activate mTOR pathways and stop autophagy. However, a small amount can be considered acceptable, particularly for electrolyte replenishment, preferably at the end of a fast. One cup of bone broth typically ranges from 31 to 86 kcal, 0.2 to 2.9 grams of fat and 4.7 to 6 grams of protein.
What is the verdict?
Fasting for metabolic health/weight loss – Does not break a fast in small quantities, but you may not get optimal results from your fast
Fasting for Gut Rest – Breaks a fast
Fasting for longevity – Yes, breaks a fast.
Lemon Water: 30mls of pure lemon juice contains 7 kcal and about 2 grams of carbohydrate. Lemon juice in water, with minimal calories and potassium, is a hydrating option that does not disrupt fasting.
What is the verdict?
Fasting for metabolic health/weight loss – Does not break fast if less than 90mls of pure lemon juice
Fasting for Gut Rest – Breaks a fast
Fasting for longevity – Lemon juice likely does not break a fast.
Diet Soda: While there are concerns about its impact on gut health and weight, diet soda generally doesn't break a fast.
Double Cream: Cream contains calories but doesn't trigger insulin responses. In small quantities, it's generally acceptable during a fast.
Almond Milk: Almond milk, in small quantities, has minimal impact on a fast due to its low-calorie content.
Oat Milk: Oat milk is high in calories and carbs, making it unsuitable for fasting.
Butter: Like cream, butter is calorie-dense but doesn't affect insulin responses when used sparingly.
What is the verdict?
Fasting for metabolic health/weight loss – Butter likely does not break a fast
Fasting for Gut Rest – Butter breaks a fast for the gut
Fasting for longevity – likely does break a fast.
Coconut Oil or MCT Oil: Technically, they contain calories but have benefits for fasting, like increasing energy expenditure and promoting ketosis. In moderation, they are generally acceptable. Bullet proof coffee contains 2 Tbsp of butter and 1 Tbsp of MCT oil which is around 320 kcals and therefore that number of calories will slow or either stop a fast.
What is the verdict?
Fasting for metabolic health/weight loss – Likely that it does not break a fast
Fasting for Gut Rest – MCT oil has minimal impact on the gut, but coffee and butter break a fast for the gut
Fasting for longevity – MCT oil likely does not break a fast.
Cinnamon: Cinnamon, when added to coffee or tea, can enhance insulin sensitivity and is unlikely to break a fast.
Salt: Salt doesn't break a fast and can improve fasting tolerance and hydration when added to water.
What is the verdict?
Fasting for metabolic health/weight loss – Salt does not break a fast
Fasting for Gut Rest – Salt does not break a fast
Fasting for longevity – Salt likely does not break a fast.
Stevia: Stevia, a non-caloric and protein free sweetener, it has no impact on autophagy usually doesn't break a fast.
What is the verdict?
Fasting for metabolic health/weight loss – Stevia does not break a fast
Fasting for Gut Rest – Stevia does not break a fast
Fasting for longevity – Stevia likely does not break a fast.
Monk Fruit: Similar to stevia, monk fruit is a non-caloric, naturally-occurring sweetener that doesn't break a fast.
Erythritol: Erythritol, another non-caloric sweetener, ingestion has shown to stimulate GLP-1 and CCK.
What is the verdict?
Fasting for metabolic health/weight loss – Erythritol does not break a fast
Fasting for Gut Rest – Erythritol breaks a fast
Fasting for longevity – Erythritol likely does not break a fast.
Xylitol: In low amounts, xylitol doesn't break a fast. Its is a sugar alcohol which is not 100% absorbed by the gut and contains protein, but likely does not activate mTOR.
What is the verdict?
Fasting for metabolic health/weight loss – Xylitol may break a fast depending on the amount
Fasting for Gut Rest – Xylitol breaks a fast
Fasting for longevity – Xylitol likely does not break a fast.
Splenda (Sucralose): While it doesn't provoke insulin responses, it may affect whole-body insulin sensitivity, so there are other concerns associated with its use.
Aspartame: Aspartame doesn't break a fast and doesn't trigger insulin or glucose responses. However, it contains phenylalanine which is metabolised into aspartic acid and methanol in the gut. The phenylalanine does activate mTOR which inhibits autophagy.
What is the verdict?
Fasting for metabolic health/weight loss – Aspartame likely does break a fast
Fasting for Gut Rest – Aspartame breaks a fast
Fasting for longevity – Aspartame likely does break a fast.
CBD Oil: CBD oil, in small non-caloric doses, doesn't break a fast.
What is the verdict?
Fasting for metabolic health/weight loss – CBD oil likely does not break a fast
Fasting for Gut Rest – Breaks a fast
Fasting for longevity – CBD oil likely does not break a fast.
Protein Powder: Protein powder DOES break a fast due to its insulin response and calorie content.
Collagen: While technically it does break a fast, small amounts are unlikely to have a significant impact on ketosis, fat-burning, or energy intake.
BCAAs: BCAAs trigger insulin responses, mTOR pathways, IGF-1 pathways and hinder autophagy, so they are generally considered to break a fast.
What is the verdict?
Fasting for metabolic health/weight loss – BCAAs likely break a fast
Fasting for Gut Rest – BCAAs breaks a fast
Fasting for longevity – BCAAs likely do break a fast.
Apple Cider Vinegar: Apple cider vinegar, has 3 kcals and 0.1 grams of carbs, with negligible calories, doesn't break a fast, but does promotes stomach acid production, so stimulates the gut.
What is the verdict?
Fasting for metabolic health/weight loss – Likely does not break a fast
Fasting for Gut Rest – Breaks a fast
Fasting for longevity – Likely does not break a fast.
Electrolytes: Sugar-free electrolytes, like Naru Revive, are compatible with fasting and can enhance fasting tolerance.
Chewing Gum: Sugar-free gum, especially those with xylitol, can usually be chewed during fasting. In very large doses (40 pieces of gum a day) have shown xylitol to cause a small spike in glucose and insulin levels. Our bodies are not able to 100% absorb sugar alcohols which can trigger our gut.
What is the verdict?
Fasting for metabolic health/weight loss – Sugar free gum does not break a fast
Fasting for Gut Rest – Breaks a fast
Fasting for longevity – SF gum likely does not break a fast.
Brushing Teeth: Brushing your teeth doesn't break a fast.
Mouthwash: Mouthwash without sugar or insulin-triggering sweeteners typically doesn't break a fast.
In conclusion, the impact of substances on fasting can vary, and individual tolerance may differ. It's crucial to consider your specific fasting goals and consult with a healthcare professional if you have any concerns or medical conditions.
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