24-Hour Fast: A Beginner’s Guide to Eat-Stop-Eat

The 24-hour fast is the main component of the Eat-Stop-Eat approach, where you refrain from any caloric intake for 24 hours 1-2 times a week. This comprehensive article will discuss everything you need to know about this intermittent fasting approach, from benefits to how to do it. 

Key Takeaways: 

• The 24-hour fasting and Eat-Stop-Eat both involve refraining from caloric intake for 24 hours, starting and stopping simultaneously. Eat-Stop-Eat follows 24-hour fasting 1-2 times weekly. 
• Choosing your fasting days, preparing hydration, and refeeding meals are crucial for this intermittent fasting approach. Only non-caloric drinks are allowed during the fasting periods.
• The 24-hour fasting and Eat-Stop-Eat promotes weight loss through ketosis, caloric reduction, and increased metabolic rate. 
• Benefits include autophagy activation, improved metabolic, brain, and gut health, and reduced inflammation.
• Potential side effects include hormonal changes, hypoglycemia, and dehydration. Some populations should seek medical advice before engaging in this diet approach.

Table of Contents:

• What Is a 24-Hour Fast?
• What Is Eat-Stop-Eat?
• How to Do a 24-Hour Fast?
• What Can I Drink on a 24 Hour Fast?
• Is a 24-Hour Fast Effective for Weight Loss?
• What Happens to Your Metabolism If You Fast for a Day?
• 24-Hour Fast Benefits
• Potential Side Effects of a 24-Hour Fast
• Foods to Eat Before and After a 24-Hour Fast
• The Bottom Line

What Is a 24-Hour Fast?

A 24-hour fast is intermittent fasting involving abstaining from caloric intake for a complete day and focusing only on non-caloric drinks.

This fasting strategy is the main component of the popular fasting approach known as Eat-Stop-Eat.

The fasting period is clearly defined, starting and ending at the same time the next day. While it may sound confusing, you still get to eat every day, even when doing this. For instance, your last meal is at 9 AM on a Monday. You will end your fast and eat something at 9 AM on Tuesday.

This consistency helps the body adapt to the fasting routine and allows a systematic approach to reaping the associated health advantages.

What Is Eat-Stop-Eat?

Coined and popularized by Brad Pilon, a nutrition expert, the Eat-Stop-Eat approach involves periodic 24-hour fasts into one’s routine, once or twice a week.

Like the 24-hour fasting, one should refrain from caloric intake for a full day, with the fasting period consistently beginning and concluding at the same time the next day. This approach aims for fasting to be simple yet effective. 

You can change the fasting schedule as you like, but here’s a sample of what a typical week of Eat-Stop-Eat meal setting looks like:

Day	Breakfast	Lunch	Dinner
Monday	Eat normally
Tuesday	Meal at 9 AM	Fast
Wednesday	Meal at 9 AM	Eat normally
Thursday	Eat normally
Friday	Eat normally		Meal at 6 PM
Saturday	Fast		Meal at 6 PM
Sunday	Eat normally

The Eat-Stop-Eat method allows you to return to your regular diet after fasting, but experts recommend getting more nutrient-dense foods to increase effects and benefits. 

Since Eat-Stop-Eat is considered a water fast, hydration is crucial when following this approach to avoid dehydration and its associated side effects. 

How to Do a 24-Hour Fast?

A 24-hour fast is straightforward: you only need to abstain from caloric intake for 24 hours. But if you’re a beginner and planning to do this, here are 3 simple steps to do it safely:

1. Choose your fasting day:

Choose a day that is convenient for you. If you plan to use the Eat-Stop-Eat method, align your activities with your fasting schedules. 

Avoid fasting when you need to exert a lot of energy, such as when hiking, running, or performing strenuous exercises. 

2. Prepare your hydration:

Hydration is crucial when fasting. Prepare your hydration choice if you want to drink liquids other than water, which we will discuss in the next section.

3. Prepare your refeeding meals:

Refeeding is also a crucial part of prolonged fasting. Doing it slowly prevents insulin, glucose spikes, and electrolyte imbalances and avoids irritating the digestive system. The last section will cover what to eat before and after fasting. 

What Can I Drink on a 24 Hour Fast?

When fasting, one can only have drinks without any calories. The following are the best options:

• Plain Water: Water has zero calories and is essential for maintaining bodily functions. Drink at least 8 glasses of water during the fasting period.
• Sparkling and Seltzer Water: Contains no calories.
• Herbal Teas: Choose your favorite variety, but chamomile, peppermint, or ginger are excellent options.
• Black Coffee: Contains caffeine, which can help suppress appetite and boost metabolism.
• Green or Black Tea: Contains caffeine and antioxidants, which boost energy and metabolism.
• Sugar-Free Electrolyte Drinks: Excellent for preventing fasting side effects. Choose ones with no calories and use natural ingredients for sweeteners.
• Zero-Calorie Sodas or Juices: They do not technically have any calories, but bodily reactions may differ per individual.

Is a 24-Hour Fast Effective for Weight Loss?

Activates Ketosis

One key aspect of a 24-hour fast and Eat-Stop-Eat is the activation of ketosis. During fasting, the body’s glucose stores are depleted, prompting a shift to utilizing stored fat for energy.¹ 

This metabolic state of ketosis leads to fat oxidation,² which contributes to sustainable weight loss. Enthusiasts often couple intermittent fasting with a keto diet to achieve faster weight loss. 

Caloric Reduction

Another primary principle behind weight loss is a caloric deficit, where the body burns more calories than it consumes. When this happens, the body needs to tap into fat for energy. 

Reduced Water Weight

In the initial stages of a 24-hour fast, individuals may experience a decrease in weight due to water weight loss. This occurs as the body releases water molecules bound to glycogen after use. 

While this reduction is temporary, it can provide a tangible and motivating early result on the scale.

Increases Growth Hormones

Fasting triggers the release of human growth hormone (HGH).³ Increased HGH levels help preserve lean muscle mass while promoting fat utilization. 

What Happens to Your Metabolism If You Fast for a Day?

Studies indicate that intermittent fasting, including 24-hour fasts, increases metabolic rate. One study even concluded that short-term fasting boosts metabolism by 14%.⁴ 

This could be attributed to factors such as an increase in norepinephrine,⁵ causing an increase in fat metabolism. 

While there is a debate on this, research suggests short-term fasting does not decrease basal metabolic rate (BMR).⁶ The body adapts to the temporary lack of incoming calories by becoming more efficient in utilizing energy from stored sources.

All these results conclude that 24-hour fasting is effective in helping one lose weight.

24-Hour Fast Benefits

Weight Loss and Increased Fat Oxidation

The core objective of the 24-hour fast is weight loss, achieved through a sophisticated metabolic process called fat oxidation. 

By abstaining from caloric intake for a prolonged period, the body transitions into a state of ketosis, utilizing stored fat for energy. This metabolic shift facilitates weight loss and promotes the reduction of adipose tissue.

Induces Autophagy

Fasting triggers autophagy. This process involves the body’s self-cleansing mechanism,⁷ eliminating damaged cells and cellular components. 

Autophagy is a crucial aspect of cellular health, promoting rejuvenation and reducing inflammation, potentially mitigating the risk of various diseases.

Boosts Cognitive Health

While the mechanism remains unclear, intermittent fasting like 24-hour fasting has neuroprotective effects.⁸ Studies also suggest intermittent fasting enhances cellular stress resistance, synaptic plasticity, and neurogenesis,⁹ promoting and boosting cognitive health.

This claim is backed by studies on intermittent fasting’s ability to delay or reverse Alzheimer’s disease¹⁰ and Parkinson’s disease.¹¹

Improves Blood Glucose Levels and Insulin Sensitivity

Due to the lack of calorie intake, intermittent fasting methods such as 24-hour fasting decrease blood sugar levels and improve insulin sensitivity. 

This has been established by an older study where a 24-hour fast resulted in lower glucose levels¹² from 158 mg/dL to 104 mg/dL. Recent studies also support 24-hour fasting’s ability to promote insulin sensitivity.¹³

These data are crucial for diabetes, PCOS, and obesity management, which all have issues with insulin resistance.  

Improved Heart Health

While there are limited studies on the 24-hour fast’s acute effects on lipid levels, research shows intermittent fasting decreases LDL levels and improves HDL levels.¹⁴ Another study shows it decreases total cholesterol and triglyceride levels.¹⁵

Moreover, there is evidence of the 24-hour fast’s ability to decrease blood pressure and improve vagal-cardiac modulation,¹⁶ resulting in improved cardiovascular health. 

Reduced Inflammation

Intermittent fasting modulates inflammation. In a study of 8-week intermittent fasting,¹⁷ subjects showed reduced inflammatory markers such as CRP and calprotectin and were seizure-free throughout the intermittent fasting duration.

This is mainly due to its ability to induce autophagy and modulate immune cells and cytokines.¹⁸ 

Improved Gut Health

Studies conclude that intermittent fasting methods like 24-hour fasting promote gut health¹⁹ by preventing bacteria overgrowth and promoting bacterial diversity, specifically increasing anti-inflammatory bacteria Lactobacillus and Bifidobacterium while decreasing harmful ones. 

Potential Side Effects of a 24-Hour Fast

Hormonal Changes

Fasting can induce hormonal fluctuations, affecting the levels of hormones such as insulin, cortisol, and growth hormone. While these changes are a natural part of the fasting process, some individuals may experience mood swings, irritability, or changes in energy levels.

Risks for Hypoglycemia

There are individuals prone to low blood sugar, mostly those with pre-existing conditions such as diabetes, but hypoglycemia can happen to some healthy people as well during fasting periods. 

If you experience symptoms such as dizziness, shakiness, and confusion, you may need to monitor your blood sugar levels or consult your healthcare provider to prevent complications.

Risks for Dehydration

Dehydration is common during fasting periods due to water loss, making adequate and proper hydration crucial. Dehydration may cause electrolyte imbalances, leading to headaches, fatigue, and dizziness.

Not for Everyone

Certain populations are not allowed to do prolonged fasting periods without medical supervision. These include:

• Pregnant and breastfeeding women
• Individuals with a history of eating disorders
• People with certain medical conditions such as heart disease or diabetes
• People under medications requiring food for proper absorption or with gastric side effects
• Individuals with low blood sugar or hypoglycemia
• Children and elderly
• Those with hormonal imbalances

Foods to Eat Before and After a 24-Hour Fast

Proper pre and post-fasting meals are equally important to ensure sustained energy and prevent complications. Here’s a quick overview of what to eat:

Before a 24-Hour Fast:

Prioritize a balanced meal that includes:

• Protein: Sources like lean meats, poultry, fish, tofu, or eggs provide essential amino acids for appetite suppression and muscle preservation.
• Healthy Fats: Avocado, nuts, seeds, and olive oil contribute to satiety and sustained energy.
• Complex Carbohydrates: Non-starchy vegetables and low-carb fruits provide a slow release of energy, helping to prevent blood sugar spikes.

After a 24-Hour Fast:

Follow this order:

• Soft and Gentle Foods: Start with easy soups on the digestive system. Opt for high protein and fat, avoiding sugar to avoid glucose spikes. 
• Protein and Fat: Start with small servings to slowly introduce protein, which is great for satisfying hunger and fat for sustained energy. Again, stay away from carbs on your first meal.
• Non-Starchy Carbohydrates: Focus on low-carb vegetables and fruits, and fermented foods.  

The Bottom Line

The 24-hour fasting and Eat-Stop-Eat methods are effective for weight loss and improving overall health. With proper planning, hydration, and a refeeding system, you will reap the benefits with minimal to no side effects. 

Frequently Asked Questions

References

¹Dhillon KK, Gupta S. Biochemistry, Ketogenesis. [Updated 2023 Feb 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK493179/

²Volek, J. S., Freidenreich, D. J., Saenz, C., Kunces, L. J., Creighton, B. C., Bartley, J. M., Davitt, P. M., Munoz, C. X., Anderson, J. M., Maresh, C. M., Lee, E. C., Schuenke, M. D., Aerni, G., Kraemer, W. J., & Phinney, S. D. (2016). Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism: clinical and experimental, 65(3), 100–110. https://doi.org/10.1016/j.metabol.2015.10.028

³Vendelbo, M. H., Jørgensen, J. O., Pedersen, S. B., Gormsen, L. C., Lund, S., Schmitz, O., Jessen, N., & Møller, N. (2010). Exercise and fasting activate growth hormone-dependent myocellular signal transducer and activator of transcription-5b phosphorylation and insulin-like growth factor-I messenger ribonucleic acid expression in humans. The Journal of clinical endocrinology and metabolism, 95(9), E64–E68. https://doi.org/10.1210/jc.2010-0689

⁴Zauner, C., Schneeweiss, B., Kranz, A., Madl, C., Ratheiser, K., Kramer, L., Roth, E., Schneider, B., & Lenz, K. (2000). Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine. The American journal of clinical nutrition, 71(6), 1511–1515. https://doi.org/10.1093/ajcn/71.6.1511

⁵Gotthardt, J. D., Verpeut, J. L., Yeomans, B. L., Yang, J. A., Yasrebi, A., Roepke, T. A., & Bello, N. T. (2016). Intermittent Fasting Promotes Fat Loss With Lean Mass Retention, Increased Hypothalamic Norepinephrine Content, and Increased Neuropeptide Y Gene Expression in Diet-Induced Obese Male Mice. Endocrinology, 157(2), 679–691. https://doi.org/10.1210/en.2015-1622

⁶Webber, J., & Macdonald, I. A. (1994). The cardiovascular, metabolic and hormonal changes accompanying acute starvation in men and women. The British journal of nutrition, 71(3), 437–447. https://doi.org/10.1079/bjn19940150

⁷Alirezaei, M., Kemball, C. C., Flynn, C. T., Wood, M. R., Whitton, J. L., & Kiosses, W. B. (2010). Short-term fasting induces profound neuronal autophagy. Autophagy, 6(6), 702–710. https://doi.org/10.4161/auto.6.6.12376

⁸Zhao, Y., Jia, M., Chen, W., & Liu, Z. (2022). The neuroprotective effects of intermittent fasting on brain aging and neurodegenerative diseases via regulating mitochondrial function. Free radical biology & medicine, 182, 206–218. https://doi.org/10.1016/j.freeradbiomed.2022.02.021

⁹Brocchi A, Rebelos E, Dardano A, Mantuano M, Daniele G. Effects of Intermittent Fasting on Brain Metabolism. Nutrients. 2022 Mar 17;14(6):1275. doi: 10.3390/nu14061275. PMID: 35334932; PMCID: PMC8954770.

¹⁰Elias, A., Padinjakara, N., & Lautenschlager, N. T. (2023). Effects of intermittent fasting on cognitive health and Alzheimer’s disease. Nutrition reviews, 81(9), 1225–1233. https://doi.org/10.1093/nutrit/nuad021

¹¹Neth, B. J., Bauer, B. A., Benarroch, E. E., & Savica, R. (2021). The Role of Intermittent Fasting in Parkinson’s Disease. Frontiers in Neurology, 12. https://doi.org/10.3389/fneur.2021.682184

¹²Gannon, M. C., Nuttall, F. Q., Lane, J. T., Fang, S., Gupta, V., & Sandhofer, C. R. (1996). Effect of 24 hours of starvation on plasma glucose and insulin concentrations in subjects with untreated non-insulin-dependent diabetes mellitus. Metabolism: clinical and experimental, 45(4), 492–497. https://doi.org/10.1016/s0026-0495(96)90225-5

¹³Sutton, E. F., Beyl, R., Early, K. S., Cefalu, W. T., Ravussin, E., & Peterson, C. M. (2018). Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even Without Weight Loss in Men with Prediabetes. Cell Metabolism, 27(6), 1212. https://doi.org/10.1016/j.cmet.2018.04.010

¹⁴Ahmed, N., Farooq, J., Siddiqi, H. S., Meo, S. A., Kulsoom, B., Laghari, A. H., Jamshed, H., & Pasha, F. (2020). Impact of Intermittent Fasting on Lipid Profile–A Quasi-Randomized Clinical Trial. Frontiers in Nutrition, 7. https://doi.org/10.3389/fnut.2020.596787

¹⁵Yuan, X., Wang, J., Yang, S., Gao, M., Cao, L., Li, X., Hong, D., Tian, S., & Sun, C. (2022). Effect of Intermittent Fasting Diet on Glucose and Lipid Metabolism and Insulin Resistance in Patients with Impaired Glucose and Lipid Metabolism: A Systematic Review and Meta-Analysis. International journal of endocrinology, 2022, 6999907. https://doi.org/10.1155/2022/6999907

¹⁶Gonzalez, J. E., & Cooke, W. H. (2022). Influence of an acute fast on ambulatory blood pressure and autonomic cardiovascular control. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, 322(6), R542. https://doi.org/10.1152/ajpregu.00283.2021

¹⁷Roco-Videla, Á., Villota-Arcos, C., Pino-Astorga, C., Mendoza-Puga, D., Bittner-Ortega, M., & Corbeaux-Ascui, T. (2023). Intermittent Fasting and Reduction of Inflammatory Response in a Patient with Ulcerative Colitis. Medicina, 59(8). https://doi.org/10.3390/medicina59081453

¹⁸Aly, S. M. (2014). Role of Intermittent Fasting on Improving Health and Reducing Diseases. International Journal of Health Sciences, 8(3), V. https://doi.org/10.12816/0023985

¹⁹Khan MN, Khan SI, Rana MI, Ayyaz A, Khan MY, Imran M. Intermittent fasting positively modulates human gut microbial diversity and ameliorates blood lipid profile. Front Microbiol. 2022 Aug 23;13:922727. doi: 10.3389/fmicb.2022.922727. PMID: 36081793; PMCID: PMC9445987.