Written by Kyle Hunt | BEXSci.
Fact checked by Andrew Lenau, ISSA CPT & Sports Nutritionist
FACT CHECKED
The 20/4 intermittent fasting diet is a refreshingly straightforward approach to weight loss in a world filled with various diets and eating plans. This method divides your day into two periods: a lengthy 20-hour fast followed by a compact 4-hour eating window.
If this sounds compelling, then you've come to the right place.
This article will unravel the fundamentals of 20/4 intermittent fasting, making it understandable for everyone, and explore its potential benefits. Whether new to fasting or seeking a fresh perspective on your dietary routine, explore how this approach can support your journey to weight loss and better health.
Table of Contents:
- What Is 20/4 Fasting?
- 20/4 Intermittent Fasting Schedule
- Benefits Of Intermittent Fasting 20/4
- 20/4 Fasting Results
- Side Effects of 20/4 Fasting
- Other Approaches to Intermittent Fasting
- What To Eat On A 20/4 Fast
- FAQs
What Is 20/4 Fasting?
The 20/4 intermittent fasting (IF) schedule is a specific eating pattern where you divide your day into two periods: 20 hours of fasting and a 4-hour eating window.
During the fasting phase, which spans most of the day, you abstain from eating and stick to calorie free drinks like water, tea, or black coffee. Then, within the 4-hour eating window, you consume all your daily calories and meals.
The 20/4 intermittent fasting schedule originated with the popular Warrior Diet, created in the early 2000s by health and fitness author Ori Hofmekler. The name comes from mimicking how ancient warriors ate, consuming small amounts of food during the day and feasting at night.
Although similar to 20/4 IF people use today, the Warrior Diet has a few distinct features. For one, you can have small amounts of raw fruits and vegetables during fasting. Snacking on some fruits and veggies can be an excellent way to hold off hunger while fasting, but they contain calories, breaking your fast. Having a small amount of calories while fasting is more of a technicality than anything. If you want to consume some low-calorie items while fasting, it shouldn't limit your progress.
However, the second difference of the Warrior Diet is how you handle the eating period. The Warrior Diet has no real restrictions on food intake. For the best results on a 20/4 intermittent fasting schedule, you want to have a plan for your eating window. Yes, consume healthy foods, but you also want to get your calories dialed in to ensure you consume optimal protein, carbohydrates, and fat.
20/4 intermittent fasting can promote various health benefits, including potential weight management. If the eating schedule fits your lifestyle, it can be very successful.
Finding Your Ideal 20/4 Fasting Schedule
One of the keys to intermittent fasting is finding an eating period that works well for you. Since everyone has unique schedules, the ideal fasting windows will differ depending on your lifestyle. Here are a few things to keep in mind when setting up your 20/4 fasting diet.
1) Align with Your Circadian Rhythm:
A circadian rhythm is an internal biological clock that regulates the sleep-wake cycle and various physiological processes in living organisms, including humans. It follows a roughly 24-hour cycle and is influenced by external cues like light and darkness. Disruptions to the circadian rhythm, such as irregular sleep patterns or exposure to artificial light at night, can significantly affect health and well-being.
Chrononutrition is a dietary approach that emphasizes the timing of food consumption in alignment with the body's circadian rhythm. Proponents of chrononutrition often recommend consuming larger meals earlier in the day and smaller meals in the evening, as well as avoiding late-night eating to allow the body's digestive system to rest during the night.
20/4 fasting works in conjunction with a chrononutrition approach. Try to have your eating window during daylight hours, as it aligns better with your body's natural cycle.
2) Adjust for Workouts:
One of the hardest things to get right with fasting is lining it up around workouts. The last thing you want to do is have your eating schedule negatively affect your workout split. The good news is, it doesn't have to.
The best option is to train in the middle of your four-hour eating window. Doing so will allow you to have a pre and post-workout meal.
Another option is to schedule your training sessions toward the end of your fasting period or right before your eating window. Some people prefer to train in a fasted state. If that is you, set it up so you can eat immediately following your workout. After a workout, prioritize protein and carbohydrates to aid in muscle recovery.
Of course, you can play around with it and experiment to see what works best for you.
3) Plan Your Eating Window:
A 4-hour eating window means consuming all your daily calories within this timeframe. With only four hours to eat your meals, it typically only allows for one or two meals. To get all of your calories and macronutrients in, it takes some planning ahead. If you don't plan, you might eat food that doesn't help you reach your goals.
Plan balanced and nutritious meals within your 4-hour eating window. Ensure you get enough high-quality protein, healthy fats, and carbohydrates to meet your nutritional needs. Include a mix of fruits and veggies to ensure you get all the necessary micronutrients. You may also want to take daily vitamin and mineral supplements to ensure you're not missing out on any nutrients.
Planning requires frequent grocery shopping to ensure you have what you need. Additionally, I recommend cooking beforehand so you already have your meals prepared when it comes time to eat.
4) Stay Hydrated During Fasting Hours:
Staying hydrated during the fasting period of a 20/4 intermittent fasting eating schedule is vital. Proper hydration helps prevent dehydration, supports metabolic functions, and can aid in appetite control, which is especially important during fasting.
Consume water, herbal teas, black coffee, or green tea to stay hydrated. Listening to your body's signals is crucial. If you feel thirsty or experience dehydration symptoms, drink some fluids.
Additionally, continue hydrating during your eating window to support digestion and overall health. It's hard to give specific recommendations for fluid intake because individual hydration needs may vary based on age, activity level, and climate. Still, the key is always to have fluids available.
5) Consistency:
You don't have to follow the 20/4 IF eating schedule every day, but it does help if you consistently stick to a similar routine. Try to eat your meals at the same time most days.
A consistent eating schedule while following a 20/4 eating plan offers several benefits. First, as mentioned, it helps regulate your circadian rhythm, enhancing the body's ability to optimize digestion and nutrient absorption during the eating window.
Second, a consistent schedule helps control hunger and reduce overeating. As your body becomes accustomed to fasting and eating periods, hunger signals decrease, making it easier to adhere to caloric goals.
Lastly, a consistent eating schedule simplifies meal planning. You know exactly how much and what you need to eat to hit your daily goals by always eating two meals per day at the same time. Check out these High Protein Meal Prep Recipes for some inspiration!
Benefits Of Intermittent Fasting 20/4
Many different intermittent fasting schedules have gained popularity in recent years. Some of the potential benefits of fasting include:
- Fat Loss: Research consistently shows that fat loss is one of the most significant benefits of intermittent fasting1. Losing weight is all about creating a negative calorie balance. Fasting much of the day makes sticking to a calorie-restricted diet easier.
- Improved Insulin Sensitivity: IF may help regulate glucose levels and improve insulin sensitivity, which reduces the risk of type 2 diabetes2.
- Heart Health: Some research suggests that IF can improve cardiovascular health by reducing risk factors like high blood pressure, cholesterol levels, and triglycerides3.
- Brain Health: Fasting may stimulate the production of brain-derived neurotrophic factor (BDNF), which supports brain health, neuroplasticity, and cognitive function4.
- Cellular Autophagy: Autophagy is a cellular self-cleaning process that becomes more active during fasting, offering multiple health benefits. It involves the removal of damaged cellular components, the disposal of intracellular pathogens, and the maintenance of overall cellular and metabolic health. Fasting, among other lifestyle factors, can stimulate autophagy, promoting the body's ability to efficiently repair and rejuvenate its cells, which may have significant implications for overall well-being and disease prevention5.
- Simplicity & Convenience: Last but not least, fasting can simplify your life. Eating less frequently reduces the time spent on food preparation and eating, making it a convenient dietary approach for some people. Additionally, many people find they are more productive during their fasting window.
20 4 Fasting Results: What To Expect
As with any dieting strategy, how well you do depends on many factors. That said, here is what to expect during your journey on a 20/4 intermittent fasting diet, based on real-life results.
20/4 Intermittent Fasting Weight Loss Results: 1 Week
The first week of time-restricted eating can be unpredictable. Depending on your starting point, you may find weight loss starts slow, or you may lose a lot of weight immediately.
This faster lost a pound a day for the first ten days: "Been doing 20:4 for the past 10 days - 10lbs off so far. Been reading that it's good to re-feed so your metabolism doesn't slow too much. So I'm thinking 20:4 weekdays and 18:6 weekends." (source)
20/4 Intermittent Fasting Weight Loss Results: 1 Month
At the one-month mark, you should have a good idea of how well the diet is going. Typically, you want to aim to lose between one and two pounds per week for sustainable weight loss.
You can lose weight faster than this, but consistency is most important. Don't sacrifice sustainability in the long term by dieting too aggressively over the first month. Remember, everyone loses weight at a different rate. It's essential to be patient and stick it out even if you start slow.
Here is one person's experience on 20/4 IF to help illustrate what you might expect.
"It took me 2 full months to lose 10lbs; 7 lbs the 1st month, and 3 lbs by the end of the 2nd month. Even though I had lost 10 lbs, my measurements were the same, and there was no difference in the way my clothes fit. By the end of my 3rd month, I had lost 19 lbs and could now see the difference in the way I looked and my clothes fitting different. My SW was 170, CW 151, GW 130. I've never been a big eater, so IF comes super easy for me. Been doing 20:4 almost the whole time (15 weeks in) with some occasional 18:6 on some weekends. Been at a plateau since 4/1 and trying to break through. No luck so far. Basically, everyone responds differently. Good idea not to compare yourself to others. Good luck!" (source)
Side Effects of 20/4 Fasting
Like any diet, a 20/4 fasting schedule has positive and negative effects. While many people experience benefits from IF, it's critical to be aware of potential side effects, which can vary from person to person. Some possible side effects of the 20/4 IF schedule include:
- Hunger & Irritability: Extended fasting periods can increase hunger and irritability, especially during the initial adjustment phase. Some individuals may find it challenging to adapt to this eating pattern. Appetite usually decreases the longer you are on the diet.
- Low Energy Levels: Fasting for an extended period may lead to decreased energy levels, particularly if you're not adequately nourishing your body during the eating window. Make sure your calorie deficit is manageable. It only takes a 500-calorie reduction daily to lose one pound per week.
- Gastrointestinal Issues: Eating many calories in one sitting can sometimes lead to digestive discomfort, bloating, or indigestion. Surprisingly, this can happen when eating an abundance of healthy foods high in fiber. If you experience GI issues, spread your calories evenly throughout the four-hour eating window or eat less fiber.
- Nutrient Deficiencies: If you don't plan your meals carefully during the 4-hour eating window, you may not get all the essential nutrients your body needs. Remember to eat a variety of lean meats, fruits, vegetables, and healthy fats.
- Social & Lifestyle Challenges: The 20/4 IF schedule can be socially challenging, as it may conflict with regular meal times or social gatherings. It may also disrupt daily routines. Try to go out still and enjoy yourself during your eating window.
Fasting is also only suitable for some. Here are a few people who should avoid a 20/4 fasting routine.
- Pregnant or Breastfeeding Women: Pregnant and breastfeeding women have increased nutritional requirements to support fetal growth and lactation. Extreme fasting can lead to nutrient deficiencies, harming the mother and the baby. Learn more in our article: Everything To Know About Intermittent Fasting For Women.
- Children & Adolescents: Growing bodies need a steady supply of nutrients, and fasting for extended periods may interfere with normal growth and development. Intermittent fasting is generally not recommended for individuals under the age of 18.
- Individuals With An Eating Disorder: People with a history of eating disorders, such as anorexia or bulimia, should avoid any form of fasting, as it can exacerbate disordered eating patterns and lead to dangerous behaviors.
- Athletes With High Nutritional Needs: Athletes, individuals engaged in strenuous physical activities, or those with high nutritional demands due to their lifestyle or profession may struggle to meet their energy and nutrient requirements within a 4-hour eating window.
2 Other Approaches to Intermittent Fasting
Of course, 20/4 intermittent fasting is not the only type of fasting. Here are two other intermittent fasting methods you could try.
1) 16/8 vs 20/4 fasting:
The primary difference between 20/4 fasting and 16/8 fasting lies in the duration of the restricted eating window. With 20/4 fasting, you fast for 20 hours and have a 4-hour eating window, whereas 16/8 fasting involves a 16-hour fast followed by an 8-hour eating window.
The 20/4 approach is more restrictive, providing a shorter eating window, potentially leading to greater calorie restriction and faster weight loss, but it can be challenging to sustain. In contrast, 16/8 fasting offers a more extended eating window, making it more manageable for many people to incorporate into their daily lives while providing potential benefits like improved insulin sensitivity and weight management.
If following a 20-hour fast is too daunting, start with a 16-hour fasting window and see how it goes.
Interested in trying the 16/8 method? We've provided a full week of meals in our article: The Best 16/8 Intermittent Fasting 7 Day Meal Plan.
2) 24-hour fasting vs 20/4:
The primary distinction between 20/4 fasting and 24-hour fasting is the duration of the fasting period. As the name suggests, a 24-hour fast involves fasting for a full day, typically from dinner to dinner or lunch to lunch.
20/4 fasting is more frequent but provides a daily eating opportunity, which can be easier to sustain for some individuals. In contrast, a 24-hour fast requires more extended periods of fasting but is performed less frequently.
A 24-hour fast can be more challenging due to the longer fasting duration. Still, it may provide more extended autophagy and potentially additional health benefits, including enhanced fat burning and cellular repair. The choice between the two depends on individual preferences, goals, and lifestyle.
What To Eat On A 20/4 Fast
During a 20/4 intermittent fasting (IF) diet, choosing foods that provide essential nutrients while helping you meet your health and dietary goals within this limited timeframe is crucial.
Here are some guidelines for the types of foods you should consider incorporating into your 20/4 IF diet:
- Proteins: Prioritize high protein low fat foods such as poultry, fish, lean cuts of meat, tofu, tempeh, beans, lentils, and low-fat dairy products. Protein helps maintain muscle mass and promotes satiety.
- Vegetables: Load up on non-starchy vegetables like leafy greens, broccoli, cauliflower, bell peppers, and zucchini. These are low in calories but rich in vitamins, minerals, and fiber.
- Whole Grains: Choose grains like brown rice, quinoa, oats, and whole wheat products over refined grains. They provide sustained energy and fiber to keep you feeling full.
- Healthy Fats: Incorporate sources of healthy fats, including avocados, almonds, walnuts, pumpkin seeds, salmon, and olive oil.
- Fruits: Don't forget fruits. Like vegetables, they are loaded with micronutrients and fiber. Eat apples, bananas, oranges, and all kinds of berries.
FAQs
Here are some answers to common questions about 20/4 Intermittent Fasting.
How does 20/4 fasting work?
20/4 fasting involves a 20-hour fasting period where you consume no calories, followed by a 4-hour eating window during which you eat your daily meals.
How much weight can you lose with 20/4 fasting?
Weight loss varies depending on various factors, but some people may experience weight loss with 20/4 fasting due to reduced calorie intake during the limited eating window. How much weight you lose depends on how severe your calorie deficit is and your exercise program.
Can you do 20/4 intermittent fasting every day?
It's possible to do 20/4 fasting daily, but it may only be suitable for some. It comes down to your daily schedule. If 20/4 IF works well for you, you can do it daily. That said, it can also be something you only do a couple of days a week.
How many calories do you eat during intermittent fasting 20/4?
The number of calories to eat during your 4-hour eating windows depends on your goals and caloric needs. To lose weight, you must eat fewer calories than your body requires to maintain weight.
How many days a week should you intermittent fast 20/4?
The frequency of 20/4 intermittent fasting can vary based on personal preferences and goals. Some people do it daily, while others opt for a few days a week. It's essential to find a schedule that suits you.
Is 20/4 better than 16/8 for fasting?
The choice between 20/4 and 16/8 fasting depends on individual preferences and goals. Both methods can be effective for different people - experiment with both to see which you like better.
What are the side effects of 20/4 fasting?
Side effects may include hunger, irritability, fatigue, and difficulty concentrating during fasting. Staying hydrated and consuming caffeine from coffee or tea can help.
Why am I not losing weight on a 20/4 fast?
Weight loss results can vary based on caloric intake, daily activity, and individual metabolism. If you are not losing weight, you need to reduce calorie intake or increase daily exercise.
20/4 Intermittent Fasting: Takeaways
The 20/4 intermittent fasting approach offers a unique way to structure your daily eating patterns. By fasting for 20 hours and restricting your eating to a 4-hour window, this regimen may yield various potential benefits, including weight management, improved insulin sensitivity, and enhanced cellular autophagy.
However, it's important to remember that fasting isn't a one-size-fits-all solution, and its suitability varies among individuals. Whether you choose 20/4 IF or another fasting method, moderation, balanced nutrition, and mindful eating remain crucial to achieving lasting health benefits.
For more information about fasting, check out our article on 6 Intermittent Fasting Methods And Schedules. And, to learn more about extended fasting, head to our 3 Day Fast Guide.
References:
- Johnstone, A. Fasting for weight loss: an effective strategy or latest dieting trend? Int J Obes 39.. https://doi.org/10.1038/ijo.2014.214
- Barnosky, A. R., Hoddy, K. K., Unterman, T. G., & Varady, K. A. (2014). Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: A review of human findings. Translational Research. https://doi.org/10.1016/j.trsl.2014.05.013
- DONG, T. A., SANDESARA, P. B., DHINDSA, D. S., MEHTA, A., ARNESON, L. C., DOLLAR, A. L., TAUB, P. R., & SPERLING, L. S. (2020). Intermittent Fasting: A Heart Healthy Dietary Pattern? The American Journal of Medicine. https://doi.org/10.1016/j.amjmed.2020.03.030
- Mattson, M. P., Moehl, K., Ghena, N., Schmaedick, M., & Cheng, A. (2018). Intermittent metabolic switching, neuroplasticity and brain health. Nature Reviews Neuroscience.. https://doi.org/10.1038/nrn.2017.156
- Bagherniya, M., Butler, A. E., Barreto, G. E., & Sahebkar, A. (2018). The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Ageing Research Reviews. https://doi.org/10.1016/j.arr.2018.08.004
Kyle Hunt
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