Intermittent Fasting Methods: Every Schedule Explained

Quick Answer: There is no single best intermittent fasting method. The right schedule depends on your experience level, goals, and lifestyle. Most people start with 16:8 (16 hours fasting, 8 hours eating), which balances effectiveness with sustainability. More aggressive protocols like 20:4 or OMAD offer deeper metabolic benefits but require adaptation.

Why the Method Matters

Intermittent fasting is not one thing. It is a category of eating patterns that share a common principle: cycling between deliberate periods of eating and not eating. The specific ratio of fasting to eating determines what metabolic processes are emphasized, how sustainable the approach is, and what results you can expect.

A 2022 systematic review in Nutrients comparing different fasting protocols found that all forms of intermittent fasting produced weight loss and metabolic improvements, but the magnitude and nature of benefits varied by protocol duration and frequency (Patikorn et al., 2022). Longer fasting windows generally produced greater autophagy and insulin sensitivity improvements, while shorter windows offered better adherence and muscle preservation.

If you are new to fasting entirely, read our complete guide to intermittent fasting before choosing a method.

Time-Restricted Eating Methods

Time-restricted eating (TRE) is the most popular category of intermittent fasting. You eat within a defined window each day and fast for the remainder. The numbers refer to fasting hours and eating hours.

14:10 -- The Gentle Start

Fast for 14 hours, eat within a 10-hour window. This is the most accessible entry point and still produces measurable results. A 2020 study in JAMA Internal Medicine found that participants following a 10-hour eating window lost weight and showed improvements in blood pressure and cholesterol without any calorie counting (Wilkinson et al., 2020).

For most people, 14:10 means finishing dinner by 8 PM and having your first meal at 10 AM. It barely feels like fasting, which is exactly the point for beginners.

Read the full breakdown: 14:10 Intermittent Fasting

16:8 -- The Gold Standard

Fast for 16 hours, eat within an 8-hour window. This is the most studied and widely practiced form of intermittent fasting. The 16-hour fast is long enough to deplete liver glycogen and initiate meaningful fat oxidation, while the 8-hour eating window provides enough time for 2-3 satisfying meals.

Research by Tinsley and La Bounty (2015, Journal of the International Society of Sports Nutrition) showed that 16:8 fasting combined with resistance training resulted in fat loss while maintaining muscle mass and strength. This makes it particularly popular among people who exercise regularly.

A typical 16:8 schedule: skip breakfast, eat from noon to 8 PM. But any 8-hour window works -- the key is consistency.

Read the full breakdown: 16:8 Intermittent Fasting

18:6 -- The Middle Ground

Fast for 18 hours, eat within a 6-hour window. This protocol pushes further into the fat-burning and autophagy zones while still allowing two comfortable meals. Many people who have adapted to 16:8 naturally progress to 18:6 as hunger signals diminish.

The additional 2 hours of fasting may seem minor, but the metabolic difference is significant. By 18 hours, most people are producing meaningful levels of ketone bodies, which provide an alternative fuel source for the brain and are associated with improved cognitive function (Mattson et al., 2018, Nature Reviews Neuroscience).

Read the full breakdown: 18:6 Intermittent Fasting

20:4 -- The Warrior Diet

Fast for 20 hours, eat within a 4-hour window. Inspired by Ori Hofmekler's "Warrior Diet," this approach concentrates all eating into a short evening window, typically one large meal and a small snack. It demands discipline and careful meal planning to meet nutritional needs.

At 20 hours of fasting, autophagy is well underway and growth hormone levels are significantly elevated. However, the narrow eating window makes it challenging to consume adequate protein and micronutrients without deliberate planning.

Read the full breakdown: 20:4 Intermittent Fasting

OMAD -- One Meal a Day

The most extreme form of daily time-restricted eating. You eat one meal per day, typically within a 1-hour window, and fast for the remaining 23 hours. OMAD produces the deepest daily fasting state and the most dramatic insulin reduction.

A 2007 study in the American Journal of Clinical Nutrition found that subjects eating one meal per day had significant reductions in fat mass compared to those eating three meals, even with the same total caloric intake (Stote et al., 2007). However, they also showed elevated blood pressure and LDL cholesterol, suggesting OMAD may not be appropriate for everyone long-term.

OMAD is best suited for experienced fasters who have already adapted to 18:6 or 20:4 and want to push further.

Read the full breakdown: OMAD: One Meal a Day

Periodic Fasting Methods

These methods involve full or near-full fasting days interspersed with normal eating days, rather than daily time restriction.

5:2 Diet

Eat normally for 5 days per week and restrict calories to 500-600 on the other 2 non-consecutive days. Popularized by Dr. Michael Mosley, the 5:2 approach has a strong evidence base. A 2018 study in the British Journal of Nutrition found that 5:2 produced equivalent weight loss and metabolic improvements to daily calorie restriction over 12 months (Carter et al., 2018).

The 5:2 method appeals to people who dislike daily restrictions. You only have to exercise discipline two days per week, and those days are low-calorie rather than zero-calorie.

Read the full breakdown: 5:2 Diet Explained

Alternate-Day Fasting (ADF)

Alternate between normal eating days and fasting days (either zero calories or up to 500 calories). ADF is one of the most studied fasting protocols. A landmark 2019 trial published in Cell Metabolism by Stekovic et al. found that 4 weeks of strict alternate-day fasting improved cardiovascular markers, reduced fat mass, and decreased the inflammatory marker CRP.

ADF is effective but demanding. Compliance rates in studies tend to be lower than with time-restricted eating, making it better suited for short-term interventions or people with strong motivation.

Read the full breakdown: Alternate-Day Fasting

Eat-Stop-Eat

Created by Brad Pilon, this method involves one or two 24-hour fasts per week. You eat dinner, then do not eat again until dinner the following day. On non-fasting days, you eat normally. It is simpler than ADF and produces a meaningful weekly caloric deficit without daily structure.

Read the full breakdown: Eat-Stop-Eat Method

36-Hour Fasts

A more extended protocol where you fast from dinner one day through the entire next day, breaking the fast at breakfast on day three. This pushes deep into the autophagy window and produces significant ketosis. It is not a beginner protocol and should be approached with medical awareness.

Read the full breakdown: 36-Hour Fast Benefits

Specialized Approaches

Circadian Rhythm Fasting

Also called early time-restricted eating (eTRE), this approach aligns your eating window with your circadian biology -- eating earlier in the day and finishing food by mid-afternoon or early evening. A 2018 study by Sutton et al. in Cell Metabolism found that eTRE (eating between 8 AM and 2 PM) improved insulin sensitivity, blood pressure, and oxidative stress even without weight loss.

This method is particularly relevant for people focused on metabolic health rather than pure weight loss. It works with your body's natural insulin sensitivity curve, which peaks in the morning and declines through the evening.

Read the full breakdown: Circadian Rhythm Fasting

Choosing the Right Method

There is no universally optimal fasting schedule. The best method is the one you can maintain consistently. Here is a decision framework:

Choose 14:10 or 16:8 if: You are a beginner, you exercise regularly, you want a sustainable long-term habit, or you need flexibility for social eating.

Choose 18:6 or 20:4 if: You have adapted to 16:8, you want deeper autophagy benefits, you prefer fewer but larger meals, or you have specific fat loss goals.

Choose 5:2 or ADF if: You dislike daily restrictions, you want flexibility on most days, or you respond better to periodic challenges than daily discipline.

Choose circadian rhythm fasting if: Your primary goal is metabolic health, you are a morning person, or you have insulin resistance concerns.

For a complete comparison with personalized recommendations, read our guide on finding the best intermittent fasting schedule.

How Fasted Helps

Choosing a method is the first decision. Sticking with it is the real challenge. Fasted lets you select any fasting protocol and tracks your progress automatically. The app shows exactly where you are in your fast, what metabolic zone you have entered, and how your current fast compares to your history. If you want to experiment with different methods -- say, 16:8 on weekdays and 18:6 on weekends -- Fasted adapts to your schedule and keeps your data organized so you can see what works best for your body.

Explore our weight loss guide to see how different methods stack up for fat loss specifically.

Frequently Asked Questions

Which intermittent fasting method burns the most fat?

All methods can produce fat loss when they create a caloric deficit. However, longer fasting windows (18:6, 20:4, OMAD) produce deeper ketosis and greater fat oxidation per fasting period. For total fat loss over time, consistency matters more than the specific protocol. A 16:8 schedule you follow every day will outperform a 20:4 schedule you abandon after two weeks.

Can I switch between fasting methods?

Yes. Many experienced fasters use different protocols on different days -- for example, 16:8 on training days and 20:4 on rest days. The body adapts to fasting as a general state; it does not require a rigid daily schedule. Fasted lets you adjust your target for each day independently.

Is 16:8 enough to trigger autophagy?

Autophagy begins at low levels around 12-14 hours of fasting and increases significantly after 16-18 hours. A consistent 16:8 practice does initiate autophagy, though longer fasts (24-48 hours) produce the most dramatic cellular cleanup. For daily autophagy maintenance, 16:8 is a reasonable minimum threshold.

How do I know which method is right for me?

Start with 16:8 for at least 2-4 weeks. If it feels easy and you want more benefits, try extending to 18:6. If 16:8 feels too difficult, step back to 14:10. Your hunger signals, energy levels, sleep quality, and overall mood are the best indicators of whether a method suits your physiology and lifestyle.

Is alternate-day fasting better than daily fasting?

Neither is categorically better. A 2017 JAMA Internal Medicine study found that alternate-day fasting did not produce superior weight loss or metabolic outcomes compared to daily calorie restriction over 12 months (Trepanowski et al., 2017). The best approach is the one that fits your life and that you can maintain.