Intermittent Fasting (IF) is often used as a blanket term to describe the health and wellness practice of restricting your eating periods.
What many people don’t realize is that there are actually five main types of IF: time-restricted feeding, alternate-day fasting, 5:2 fasting, eat-stop-eat, and the warrior diet.
Each of these methods has its own pros and cons and may be more or less suitable for different individuals based on their lifestyles, health goals, and the unique response of their bodies to fasting.
It’s not just about fasting, it’s also about finding the right fasting schedule that works best for you.
In this article, we’ll help you understand each type, navigate the pros and cons, and pick the best fasting schedule tailored to your needs.
What Is a Fasting Schedule?
A fasting schedule is a plan that outlines when and for how long you will fast.
You should think of it as a roadmap for your intermittent fasting journey: it sets the guidelines for how long you will abstain from food and when you can eat. For example, if you’re on a 16:8 fasting schedule, this means that you will fast for 16 hours and eat during an eight-hour window.
The most common fasting schedules are based on the number of hours of fasting and eating. However, some methods also involve calorie restrictions or specific food choices during the eating periods.
For example, the warrior diet involves eating just one large meal at night, whereas the 5:2 fasting method allows for normal eating for five days and then restricting calories to 500-600 on two non-consecutive fasting days.
A fasting schedule helps you maintain a consistent fasting routine, allows your body to adapt and adjust to the changes, and ultimately benefits your overall health and well-being.
Now, let’s take a closer look at each type of intermittent fasting and their respective pros and cons.
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What Is the Most Effective Fasting Schedule?
The most effective fasting schedule for you is dependent on your goals and lifestyle. For example, if your goal is weight loss, time-restricted feeding may be a better option than alternate-day fasting as it allows for more consistent calorie restriction and many people find it easier to stick to.
However, if you’re looking to improve insulin sensitivity and lower inflammation, research has suggested that alternate-day fasting or the 5:2 diet have these benefits, but again, this is dependent on what best suits your life and schedule..
This will all make sense as we look at the pros and cons of each intermittent fasting schedule. It’s important to remember that it will take a certain degree of trial and error to find the best time to fast for your body’s unique response.
Time-Restricted Eating (TRE)
TRE is the star of IF, not because it’s the only method that works, but because it’s the most popular and easiest to follow.
TRE involves restricting your eating periods to a specific window of time each day (usually between 8-12 hours) and fasting for the remaining hours (9). You can think of it as an eating schedule rather than a diet, as it’s less about what and how much you eat and more about when you eat.
Under the umbrella of TRE, there is:
You eat and fast for equal parts of the day, eating during a 12-hour window, then switching off the kitchen lights for the next 12. Technically, you can consider this to be the most beginner-friendly version of time-restricted eating.
Unfortunately, it may not provide the full benefits of IF, such as increased autophagy (the process of cellular repair and renewal). Depending on your meal choices, it may even fail to cause a calorie deficit, which means that it may not lead to weight loss.
You eat for 10 hours and fast for 14. This is a bit more challenging, but it’s nothing most people can’t handle (you’re only delaying eating breakfast by 2 hours). This type of time-restricted eating is considered the minimum to reap some of the weight-loss benefits of IF.
This is where things start to become serious. You fast for 16 hours and have an eight-hour window in which to eat. This is called the “magic fasting ratio” because it’s believed to be the minimum required to experience more significant health benefits such as improved metabolic health and more significant weight loss (7).
You eat in a six-hour window and fast for the remaining 18 hours. This requires a bit more planning (and a lot more willpower), but it could truly kick-start your body’s fat-burning potential.
You fast for 20 hours and eat during a four-hour window. This is intense, but it has its own set of potential benefits, such as more significant weight loss and improved insulin sensitivity.
This is the ultimate challenge – the one-meal-a-day (OMAD) plan. You eat just one meal during a one-hour window and fast for the remaining 23 hours. It isn’t for everyone, but those who can master it have reported incredible benefits.
Read more: The 36-Hour Fast: Reset Your Mind and Body
Now, let’s take a closer look at the pros and cons of TRE:
- Easier to follow than other fasting schedules (particularly 12/12 and 14/10)
- Provides flexibility in food choices and meal timing
- Can be customized based on personal preferences and lifestyle
- May lead to weight loss, improved metabolic health, and lower inflammation
- May improve digestive symptoms by allowing the body more time to rest and repair
- May not provide the full benefits of IF (such as increased autophagy) with shorter fasting periods
- Requires discipline and consistency to stick to a set eating window
- May be challenging for those with busy schedules or those who struggle with hunger during fasting periods
- Depending on meal choices, it may not result in a calorie deficit, so there will be no weight loss
- Some people may experience fatigue or low energy levels during fasting periods
Alternate-Day Fasting (ADF)
As the name suggests, ADF involves alternating between days of normal eating and days with either no food or very limited calories (approximately 500-600) (2).
For example, you may eat normally on Monday, fast on Tuesday, and repeat this pattern throughout the week.
- A larger calorie deficit is likely to lead to more significant weight loss
- It is believed to promote autophagy in longer fasting periods
- Harder to stick to for some individuals, depending on their lifestyle and schedule
- May lead to overeating on eating days
- May not be sustainable over long periods of time
- It is not suitable for those with underlying health conditions or who are taking certain medications
Similar to ADF, the 5:2 fasting schedule involves eating normally for five days of the week and then restricting caloric intake to approximately 500 calories on two non-consecutive days of the week (1). This is a great intermittent fasting schedule for women as it is not too restrictive.
- Less restrictive than complete alternate-day fasting
- May promote increased insulin sensitivity and autophagy on fasting days
- May not be sustainable for longer periods of time
- Can lead to overeating on non-fasting days if it is not carefully planned
This is considered to be one of the more challenging methods. ESE involves a complete 24-hour fast once or twice a week (8). This means eating dinner, fasting for 24 hours, and then resuming regular meals the following day at dinner time.
- Can help with weight loss and may have metabolic health benefits
- Believed to promote autophagy in longer fasting periods
- Requires planning and willpower to complete full 24-hour fasts
- May not be suitable for those with underlying health conditions or who are taking certain medications
The Warrior Diet
This fasting schedule is based on the idea of mimicking the eating patterns of our ancient ancestors.
It involves a 20-hour fast followed by a four-hour “feeding window” during which you consume one large meal and you can eat small snacks for the remaining time.
- Believed to increase fat-burning potential during longer fasting periods
- Provides structure for meal planning and portion control
- Not suitable for those who have a history of disordered eating or restrictive eating habits
- May not be sustainable for longer periods of time
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So, Which Is the Best Fasting Schedule?
We hate to break it to you, but there really isn’t a “best” intermittent fasting for weight loss schedule. It is ultimately dependent on your personal goals, lifestyle, and preferences.
If simplicity and flexibility are important to you, TRE may be the way to go.
If you want a more intense approach with the potential for significant weight loss and autophagy, ADF or ESE may be worth considering. Or if you prefer structure and mimicking our ancestral eating patterns, the Warrior fasting diet plan could be a good fit.
The key is to find a fasting schedule that works for you and your body.
So, how do you know if a fasting schedule is or isn’t working for you? Well, there will be some tell-tale signs.
If you notice positive changes in your weight, energy levels, and health markers, then the fasting schedule is likely beneficial for you. However, if you experience extreme hunger or fatigue, difficulty sticking to the schedule, or negative changes in your mental or physical well-being, it may be time to re-evaluate and try a different approach.
A certain degree of discomfort and adjustment is expected when you start any new fasting schedule, but it should not cause significantly negative effects on your health.
It is important to consult your healthcare provider before you start any fasting regimen.
What Is the Best Fasting Schedule for Fat Loss?
There is a more solid answer for this one – any schedule that causes a calorie deficit will result in weight loss (12). This means that if the fast results in you consuming fewer calories, you are likely to lose weight.
However, this deficit needs to be sustained over time and certain schedules may be easier to stick to in the long term, which will lead to more sustainable results.
Our best advice is to consider your lifestyle and preferences. You should choose a fasting schedule that fits into your daily routine and allows you to make healthy food choices that you enjoy.
For example, if you work out in the morning, it’s unreasonable to fast until lunchtime or at all. Therefore, you may want to schedule your fasts for days when you don’t exercise or on your rest days.
You should also be mindful of long-term sustainability. While some fasting schedules may produce quick results, you need to consider if they are something you can realistically stick to for weeks or months at a time.
If not, it may be better to choose a less restrictive schedule that allows greater flexibility and enjoyment in your eating habits.
Finally, don’t ignore the science. Fat loss can only occur as a result of a calorie deficit (3). Therefore, if you don’t see any results with your chosen fasting schedule, it’s important to reassess your caloric intake and make adjustments accordingly.
Frequently Asked Questions
What is the 4-4-12 fasting rule?
The 4-4-12 fasting rule is an eating pattern where you eat breakfast, wait 4 hours, eat lunch, wait another 4 hours, then eat dinner, followed by a 12-hour fast.
A typical day may look something like this: breakfast at 8 AM, lunch at noon, dinner at 4 PM, and then you don’t eat again until 8 AM the following day. Essentially, you fast for 12 hours every day (similar to the 12/12 type of TRE we discussed earlier) and avoid snacking between meals.
This approach is considered a form of time-restricted eating and may be beneficial for weight loss, insulin sensitivity, and digestion. However, it may not provide the same level of benefits in terms of autophagy as those provided by longer fasting periods (11).
In addition, unless you consciously create a calorie deficit, it may not result in significant weight loss (3).
Is it better to fast for 12 or 16 hours?
Both 12-hour and 16-hour fasting windows can provide health benefits, but they serve different purposes.
A 12-hour fasting window is easier to maintain and may improve digestion and insulin sensitivity. In contrast, a 16-hour fast may contribute more significantly to the promotion of autophagy, the body’s process of cleaning out damaged cells, and weight loss as it is more likely that it will create a larger calorie deficit (10).
Does 16/8 fasting reduce belly fat?
Yes, the 16/8 fasting method can help reduce belly fat. It restricts your eating window, which can naturally lead to a reduction in calorie intake. However, you must also consume healthy, nutritious food during your eating window.
Simply fasting without making any dietary changes may not yield the desired results. You should consider asking a registered dietitian to help develop an intermittent fasting 7-day meal plan for you if you are unable to create one yourself.
What is the best intermittent fasting window to lose belly fat?
There is no “best” fasting schedule for losing belly fat. However, the 16/8 fasting window is a popular choice that can lead to weight loss and potentially target belly fat (6).
Fasting consistently and making healthy food choices during your eating window are key factors for achieving results. However, it’s important to remember that spot reduction of belly fat is not possible – overall weight loss and body fat reduction will lead to a decrease in belly fat.
How long does it take for 16/8 intermittent fasting to work?
The time it takes to notice the effects of 16/8 intermittent fasting can vary. Some people may see changes as quickly as in two weeks, while it may take a few months for others.
It is dependent on several factors, including the quality and quantity of the food you eat during your eating windows, your level of physical activity, and your overall metabolic health.
Does sleeping count as fasting?
The hours you spend sleeping count towards your fasting period. This is why many people find it beneficial to include their sleeping hours in their fasting window, as it makes the fasting period feel less challenging.
Is it OK to fast for 16 hours every day?
Yes, many people maintain a daily 16-hour fast and find it sustainable and beneficial for weight management and overall health.
Research has suggested that it may lead to health improvements, including improved blood sugar control and weight loss, so it may be a good option for those who are looking to make long-term changes to their eating habits (4).
What is the 20/4 rule for fasting?
The 20/4 rule, which is also known as the Warrior Diet, involves fasting for 20 hours and eating within a four-hour window each day. During the fasting period, small amounts of fruits and vegetables are permitted. This type of intermittent fasting is quite intense and may not suit everyone. It’s important to approach it with caution and consider seeking professional guidance before you start.
The Bottom Line
The best fasting schedule is that which suits your lifestyle and allows you to make healthy food choices while also maintaining a calorie deficit over time. Whether this is a 12-hour, 16-hour, or longer fast, what matters is how sustainable the schedule is.
It’s also important to remember that weight loss is not the only benefit of fasting – improved metabolic health and overall wellness should also be considered as important intermittent fasting benefits.
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!
- A randomised controlled trial of the 5:2 diet (2021, ncbi.nlm.nih.gov)
- Alternate-day fasting and chronic disease prevention: a review of human and animal trials (sciencedirect.com)
- Fat loss depends on energy deficit only, independently of the method for weight loss (2007, pubmed.ncbi.nlm.nih.gov)
- INTERMITTENT FASTING AND HUMAN METABOLIC HEALTH (2015, ncbi.nlm.nih.gov)
- Intermittent Fasting and Metabolic Health (2022, mdpi.com)
- Intermittent fasting and weight loss (2020, ncbi.nlm.nih.gov)
- Intermittent Fasting in Weight Loss and Cardiometabolic Risk Reduction: A Randomized Controlled Trial (2022, journals.lww.com)
- Intermittent Fasting Programs and Their Effects on Body Composition: Implications for Weight-Restricted Sports (2015, journals.lww.com)
- Perspective: Time-Restricted Eating—Integrating the What with the When (2022, sciencedirect.com)
- System-wide benefits of intermeal fasting by autophagy (2017, ncbi.nl.nih.gov)
- The effect of prolonged intermittent fasting on autophagy, inflammasome and senescence genes expressions: An exploratory study in healthy young males (2023, sciencedirect.com)
- “Calories in, calories out” and macronutrient intake: the hope, hype, and science of calories (2007, journals.physiology.org)