Intermittent Fasting: What You Can and Can't Eat

Find out which foods you can and cannot eat when cheating on an intermittent fast if your goal is to experience the full benefits of fasting without undermining your progress.

Intermittent Fasting: What You Can and Can't Eat
  • While cheating during intermittent fasting can temporarily disrupt fat-burning and insulin sensitivity, occasional breaks may not significantly affect long-term results if overall caloric intake and adherence to fasting are maintained.
  • Certain fasting-friendly nutrients like glucomannan, magnesium, and electrolytes can be consumed during the fasting window without breaking the fast, helping to manage hunger, maintain hydration, and support overall well-being.
  • Supplements like Jung+ Fasting Tonic™ enhance fasting by replenishing vital micronutrients, supporting gut health, and preventing muscle loss, helping to ensure a more effective fasting experience.

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Intermittent Fasting: What You Can and Can't Eat

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Intermittent fasting has gained popularity as an effective tool for weight control, boosting longevity mechanisms, and improving overall health. However, sticking to a strict fasting schedule can be challenging, leading some to consider "cheating" during the fasting window. So, can you really snack while fasting, or will this sabotage your efforts?

In this article, we'll discuss what foods you can and cannot eat when cheating on an intermittent fast if your goal is to experience the full benefits of fasting without undermining your progress.

Learn more about intermittent fasting and how to cheat effectively.

What Foods Break an Intermittent Fast? What Foods Don't?

Intermittent fasting (IF) is an eating pattern where you alternate between defined periods of eating and fasting, such as 16 hours of fasting with an 8-hour eating window, or fasting for a full 24 hours once a week.

This approach offers numerous benefits, yet challenges like strong cravings or hunger pangs can arise, often triggered by hormonal fluctuations, stress, disruptions in the sleep-wake cycle, or nutritional deficiencies.

While on diets, many people occasionally indulge in a "cheat meal" or "cheat day" to ease the mental strain of continuous dietary restrictions. They choose either a predetermined day to enjoy their favorite, albeit less healthy, foods or simply allow themselves to overeat.

But how does "cheating" fit into the framework of intermittent fasting? What constitutes a breach during the fasting period, especially when almost anything goes during the eating window? Let's find out.

Cheating vs. Breaking a Fast

When discussing the concept of cheating during intermittent fasting, it's important to understand that breaking a fast isn't inherently wrong.

Breaking a fast is simply the act of consuming calories during the designated fasting window. This doesn't necessarily equate to cheating on your diet, although it can change the way your body responds to IF. 

In fact, some experts argue that planned occasional breaks from fasting can provide a mental respite and improve long-term adherence. And moreover, research shows that occasional deviations from a fasting schedule can have minimal impact on overall results if a consistent pattern is maintained in the long term.

Short-Term vs. Long-Term Impact

Eating during your fasting window may disrupt some short-term metabolic benefits, such as enhanced fat-burning or insulin sensitivity. 

However, the long-term effects of intermittent fasting, such as weight loss and improved metabolic health, are more closely tied to overall caloric intake and adherence to a regular fasting schedule. Ultimately, occasional breaks from fasting won't negate the cumulative benefits of a consistent IF regimen.

A crucial aspect of IF is adaptability and flexibility. Placing undue stress on maintaining a perfect fasting schedule may cause more harm than good. What's most important is to return to the regimen immediately after breaking your fast. 

What You Can Eat During Fasting Windows Without Breaking Your Fast

While some degree of flexibility can be intertwined into a fasting routine, for the best results, minimize the frequency of episodes in which you eat outside of your eating window. Here are foods and drinks you can consume without really breaking your fast:

  • Water: Essential for hydration and helps keep you feeling full.
  • Black Coffee: Contains almost no calories and can help suppress appetite.
  • Tea: Unsweetened and without milk, herbal teas, green tea, and black tea are good choices.
  • Electrolytes: Zero-calorie electrolyte drinks or adding a pinch of salt to water can help maintain electrolyte balance, especially during longer fasts.
  • Apple Cider Vinegar: Diluted in water (1-2 tablespoons), it can help with satiety and insulin sensitivity without breaking the fast.
  • Sparkling Water: Plain, unsweetened, and without added flavors, sparkling water can be a refreshing option.

Additionally, you can take certain supplements while fasting to help amplify the benefits you experience and reduce side effects. Fasting-friendly nutrients (that don’t break a fast) can help solve deficiencies and improve the performance of a fasting regimen.

Fasting-Friendly Nutrients

1. Glucomannan

Glucomannan, a dietary fiber derived from the konjac root, plays a pivotal role in promoting a feeling of fullness, which can lead to a natural reduction in calorie intake and assist in weight loss. 

As glucomannan expands in the stomach, it reduces the urge to overeat, making it easier to manage portion sizes and reduce overall caloric consumption. Additionally, it helps maintain steady blood glucose levels, a critical factor in preventing insulin resistance and promoting healthy longevity. Glucomannan also supports gut integrity, reduces inflammation, and enhances overall well-being during fasting (1).

2. Magnesium

Magnesium is a key nutrient that can be taken while fasting without breaking your fast. Here are some of the benefits magnesium provides while fasting:

  • Helps prevent muscle cramps, which often occur during fasting due to electrolyte imbalances.
  • Aids in cellular energy production, reducing fatigue and maintaining energy levels throughout fasting.
  • Improves sleep quality, promotes relaxation, and reduces anxiety by regulating neurotransmitters, making it easier to tolerate fasting without stress.
  • Enhances insulin sensitivity, helping to stabilize blood sugar levels and reduce the risk of energy crashes or food cravings during fasting.
  • Helps regulate blood pressure and maintain a stable heart rate, promoting overall heart health.

Since magnesium contains no calories and does not raise insulin levels, it's a perfect fasting-friendly option that supports overall well-being and can make fasting more comfortable (2).

3. Electrolytes (Sodium, Potassium, and Chloride)

Fasting restricts food and drink intake, which can deplete electrolyte levels in the body, leading to headaches, fatigue, muscle cramps, and even dizziness (3).

Sodium helps regulate water balance and supports nerve function. Potassium is essential for maintaining normal heart rhythm and muscle function, while chloride aids in fluid balance and the production of digestive acids.

Consuming electrolytes during fasting won't break your fast as long as they are free from added sugar or glucose. However, many electrolyte blends contain sugar, which can raise insulin levels and disrupt your fast. It's important to choose electrolyte supplements specifically designed for fasting, free of sweeteners and additives, to stay hydrated and balanced without breaking your fast.

4. Creatine

Creatine is a compound that aids in energy production, muscle strength, and performance, which may decline during fasting. It has minimal calories and is unlikely to significantly disrupt a fast. 

Creatine assists your cells in ATP regeneration, crucial for maintaining muscle function without breaking your fast, and helps increase muscle cells' water content, a process known as cell volumization. This offers an anabolic (muscle-building) effect that helps retain muscle mass during times of stress (4).

5. Ca-HMB

Ca-HMB, derived from the amino acid leucine, is known to reduce muscle breakdown and support muscle maintenance during fasting. It aids in recovery and performance. While primarily known for enhancing muscle strength and performance, Ca-HMB also supports a leaner body composition by promoting muscle mass and reducing body fat during fasting (5).

5. Mineralized Seaweed 

Mineralized seaweed is a nutrient-rich supplement that supports the body without breaking a fast. It is packed with natural minerals such as calcium, potassium, and magnesium, which aid in muscle function, nerve signaling, and cellular energy production, helping the body function smoothly during fasting. 

Seaweed helps restore electrolyte balance, reducing the risk of common fasting issues like muscle cramps, fatigue, dizziness, headaches, and dehydration (3). Additionally, the iodine in seaweed supports thyroid health, which is vital for maintaining a healthy metabolism, especially during fasting when calorie intake is low (6).

Since mineralized seaweed contains no calories, sugar, or protein, it doesn’t trigger an insulin response, making it an ideal choice for fasting. Unlike processed electrolyte blends that often contain added sugars or sweeteners, seaweed offers a natural source of minerals without disrupting your fasting routine.

What About Matcha (Green Tea)?

The question of whether matcha breaks a fast is nuanced, as it depends on the type of matcha and the specific type of fast. While 100% pure (unsweetened) matcha contains very few calories, its impact on metabolism and gut health suggests it might influence fasting outcomes.

Pros:

  • Unsweetened matcha is low in calories, typically around three calories per gram, which may not significantly interfere with fasting aimed at calorie restriction.
  • Studies show that matcha can increase fat oxidation and improve metabolic health, which may be advantageous during fasting.
  • Matcha has been shown to regulate lipid metabolism and support gut health, which can further benefit the body during fasting.

Cons:

  • Matcha may stimulate metabolic processes, potentially affecting fasting states.
  • Some people experience side effects on an empty stomach, such as nausea, vomiting, and abdominal discomfort, which can interfere with fasting.

Despite these benefits, it’s generally not recommended to consume matcha during fasting due to its potential to disrupt the fasting window.

What About Bone Broth?

When considering whether bone broth disrupts fasting, there are both pros and cons, depending largely on the goals of the fast. Some people consume small amounts of bone broth during extended fasts for its electrolytes and minerals, though it does contain a few calories. But is this a good idea?

Pros:

  • Bone broth is rich in electrolytes such as sodium, potassium, calcium, and magnesium, which help replenish vital minerals and prevent issues like dehydration, muscle cramps, and fatigue during fasting.
  • It typically contains very few carbohydrates and is relatively low in calories, so it may not significantly affect insulin levels or disrupt fasting aimed at ketosis or fat-burning.
  • Collagen, amino acids, and gelatin in bone broth help maintain gut health by strengthening the intestinal lining, which can be beneficial during longer fasts when the digestive system is less active.
  • The savory flavor and modest protein content of bone broth can help curb hunger, making it easier to stick to a fast for extended periods.

Cons:

  • Bone broth contains some protein, which can stimulate mTOR (a pathway associated with cellular growth) and potentially interrupt autophagy, one of the key benefits of prolonged fasting.
  • Despite being low in calories, bone broth still contains some, which can disrupt strict water-only fasting aimed at complete metabolic rest or deep cellular repair.
  • The small amounts of protein and fat in bone broth may cause a slight insulin response, which can interfere with fasting goals, particularly if the aim is to keep insulin levels low.

While bone broth offers benefits like electrolyte replenishment and hunger control, it is generally not recommended during the fasting window due to its potential to disrupt the fasting state.

How to Maintain Nutritional Balance While Fasting

To maintain nutritional balance while fasting and minimize cheating or breaking your fast window due to stress or improper diet plan, consider the following strategies:

  • Prioritize nutrient-dense foods: During your eating window, choose foods that are high in fiber, protein, and healthy fats. These nutrients will help keep you feeling full and satisfied, reducing the temptation to eat outside your designated eating window.
  • Stay hydrated and maintain electrolytes balance: Sometimes, your body may confuse thirst for hunger, so staying hydrated can help avoid unnecessary snacking.
  • Plan your meals: Knowing what you'll eat during your eating window can help prevent impulsive decisions that might lead to cheating. Prepare healthy meals and snacks in advance to stay on track with your fasting goals.
  • Manage stress: Emotional eating can be a major culprit in breaking your fast. Practice stress-management techniques, such as meditation, exercise, or breathing, to help prevent emotional eating.
  • Timing your eating windows is a crucial aspect of intermittent fasting that can significantly influence your results. 
  • Use supplements to avoid deficits and support your body during a fast window. 

Managing Hunger and Cravings When Fasting

Glucomannan:

Glucomannan reduces appetite and maintains stable blood glucose levels. By promoting a feeling of satiety, it helps control portion size and calorie intake. Glucomannan also supports gut health, reduces inflammation, and promotes overall health during fasting.

Zero Calorie Fibers: 

Zero-calorie fibers, similar to glucomannan, are an effective way to combat hunger and food cravings during fasting. These fibers expand in the stomach, creating a sense of fullness without adding calories or breaking the fast. 

Psyllium husks, often found in digestive supplements, help regulate bowel function and keep you feeling satisfied for longer. Inulin, a prebiotic fiber found in foods like chicory root, supports gut health while also reducing hunger. Incorporating these fibers can help control appetite and cravings, making fasting easier and more comfortable.

Hydration:

When the body is dehydrated, it can mistake thirst for hunger, making fasting more challenging. Drinking enough water throughout the day helps suppress false hunger signals, maintain stable energy levels, and support overall health during fasting. 

Proper hydration also aids digestion, reduces fatigue, and keeps the body functioning optimally. Additionally, consuming electrolyte-rich beverages (without sugar) is important to restore water and salt balance, which can be disrupted during fasting.

Caffeine:

Caffeine acts as a natural appetite suppressant by stimulating the central nervous system and increasing adrenaline levels, temporarily reducing hunger. Additionally, it speeds up metabolism and enhances fat oxidation, helping the body use stored fat for energy during fasting. 

However, it's important to consume caffeine in moderation to avoid side effects like nervousness, dehydration, or sleep disturbances, especially if you have a sensitive stomach or a history of gastrointestinal problems. Black coffee with no added sugar is an ideal choice, as it won't break your fast and can help manage feelings of hunger effectively.

Small Amounts of Healthy Fats:

If you feel hungry during your fasting window, consuming a small amount of healthy fats, such as a teaspoon of coconut oil, MCT oil, or a small serving of nuts or avocado, might help. When consumed in small amounts, healthy fats can be converted into ketones (7). It doesn’t technically break a fast because ketones fulfill energy needs without causing insulin or blood sugar spikes.

Omega-3 fatty acids are particularly important for brain function. Found in sources like fish oil or flaxseed, these fats support cognitive health, memory, and mood regulation (8). By supplying the brain with essential nutrients without disrupting the fast, omega-3s can be a helpful addition to IF, offering mental clarity while allowing the body to benefit from fasting’s metabolic effects. However, intake should be kept minimal to maintain the fasted state.

Yerba Mate:

Yerba mate is a traditional South American tea known for its stimulating properties, similar to coffee and green tea. It contains caffeine, theobromine, and other beneficial compounds that can help suppress appetite through the same mechanism as Ozempic and other GLP-1s and boost energy levels, which may be helpful during fasting (9).

Jung’s Fasting Tonic™

Fasting Tonic™ redefines fasting with a precision nutrient drink mix, making calorie restriction and fasting both easier and safer. It delivers an optimized nutrient environment for fasting and calorie restriction while helping to mitigate side effects like fatigue.

Fasting Tonic™ goes beyond mere appetite management. This advanced formula replenishes vital micronutrients, supports essential gut bacteria, supports healthy energy levels, and protects against muscle loss, ensuring a more effective and comfortable fasting experience. Importantly, it helps to safeguard against muscle loss, a major concern with fasting routines, making it a comprehensive ally for your fasting journey.

Key Takeaways on What to Eat While Practicing Intermittent Fasting

Determining an adequate fasting window, maintaining a balanced diet, and incorporating supplements into your intermittent fasting regimen will greatly improve your fasting experience and overall health.

Remember, the goal of intermittent fasting is not just calorie restriction, but to optimize the body's natural processes for longevity and wellness. Making informed decisions about your diet during the eating window, managing any deviations during the fasting window, and taking appropriate supplements will help you achieve successful and sustainable results on the road to longevity.

 

  1. Sood N, Baker WL, Coleman CI. Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis (2008). The American Journal of Clinical Nutrition
  2. Magnesium in Man: Implications for Health and Disease (2015). Physiological Reviews.
  3. Is Water-Only Fasting Safe (2021)? Global Advances in Health and Medicine
  4. Creatine supplementation affects muscle creatine during energy restriction (2001). Medicine and science in sports and exercise
  5. Beta‐hydroxy‐beta‐methylbutyrate supplementation and skeletal muscle in healthy and muscle‐wasting conditions (2017). Journal of Cachexia, Sarcopenia and Muscle.
  6. Thyroid function and iodine intake: global recommendations and relevant dietary trends (2024). Nature Reviews Endocrinology.
  7. Pathways and control of ketone body metabolism: on the fringe of lipid biochemistry (2004). Prostaglandins, Leukotrienes and Essential Fatty Acids.
  8. Effects of Omega-3 Polyunsaturated Fatty Acids on Brain Functions: A Systematic Review (2022). The Cureus Journal of Medical Science.
  9. Mate tea (Ilex paraguariensis) promotes satiety and body weight lowering in mice: involvement of glucagon-like peptide-1 (2011). Biological and Pharmaceutical Bulletin.