Intermittent Fasting Schedule: Common Options Compared

In 30 seconds

Common intermittent fasting schedules are daily eating windows, like 12:12, 14:10, 16:8, 18:6 and 20:4, and weekly patterns, like 5:2 or alternate-day fasting. Trials found broadly similar average effects on weight and many cardiometabolic markers, so no schedule is proven best. Start with the gentlest one that fits your life.

• No clear large winner: trials found broadly similar average effects across popular schedules.
• Daily schedules differ mainly in window length, and a narrower window isn't proven better.
• Earlier eating windows show signals for better glucose in small, short studies, but findings vary.
• Start with the gentlest schedule you can keep and move one step at a time.

Which schedule should you start with?

Start with the gentlest schedule that fits your routine, then move one step at a time. In randomized trials, common schedules (daily eating windows, alternate-day fasting and 5:2) had broadly similar average effects, so the one you can keep matters more than its name.

Randomized-trial syntheses find that common intermittent fasting schedules have broadly similar average effects on body weight and many cardiometabolic outcomes, although individuals may respond differently.Source 11

Each schedule has its own guide: 12:12, 14:10, 16:8, 18:6, 20:4, 5:2 and alternate-day fasting.

Try a schedule

Example times. Nothing is saved.

Schedule

12:1214:1016:818:620:4

Last meal

8:00 PM

Fasting

16 h

Eating window

8 h

Fast ends

12:00 PM

Eating window: 12:00 PM to 8:00 PM. Hours on a clock are not a measurement of your body.

Open the fasting calculator

What does a day look like on each daily schedule?

Does one schedule work better?

A network meta-analysis of randomized trials found broadly similar average effects on body weight and many cardiometabolic risk factors across common schedules. Differences depended on how trials defined each diet, how closely people followed it and how long trials ran, so no schedule is shown to be better for everyone.Source 11

Does eating earlier in the day help?

It might help blood sugar, but the evidence is early.

Earlier daily eating windows have improved glucose, insulin sensitivity and some cardiometabolic markers in short trials and timing-focused reviews, but results vary and don't apply to everyone.Source 22Source 33Source 44

Most of these studies were small and short, so treat them as a signal, not a rule. The early vs late eating window guide goes into more detail.

Small crossover and short trials show the effect is possible, for example better insulin sensitivity or 24-hour glucose, but they are limited by size, length and who took part.Source 33Source 44

A timing-focused network meta-analysis found mixed results; pooled comparisons often favored earlier eating windows for some metabolic measures, but differences between studies limit broad conclusions.Source 22

In a small crossover trial in men with prediabetes, an earlier window improved insulin sensitivity, blood pressure and oxidative stress markers without weight loss. A short study found better 24-hour glucose and shifts in body-clock gene markers. Neither shows when processes such as autophagy start.Source 33Source 44

Who should check with a clinician first?

Talk to a qualified health professional before fasting if you are pregnant or breastfeeding, under 18, living with or recovering from an eating disorder, have diabetes, take insulin or a medicine affected by meal timing, are an older adult, or are acutely ill. Do not change the dose or timing of any medicine without your clinician. See Blimbi’s safety guide.

Related guides

• 20:4 Intermittent Fasting: How It Works

  20:4 intermittent fasting means about 20 hours of fasting and a 4-hour eating window. See a sample day, what trials found and when a gentler schedule wins.

• 16/8 Fasting: How It Works and How to Start

  16/8 fasting (also written 16:8) means about 16 hours of fasting and an 8-hour eating window. See a sample day, how to build up to it and what trials found.

• Early Intermittent Fasting: Does an Earlier Window Help?

  An earlier window improved 24-hour glucose in a small trial. Early intermittent fasting has no one schedule for everyone, so keep a window you can hold.

• Fasting-Mimicking Diet: What a 3-Month Trial Found

  The fasting-mimicking diet means 5 low-calorie days a month. A 3-month trial with commercial ties found lower weight and blood pressure. Its limits and who should avoid it.

• Missed a Fast or Ended Early? What Now

  Missed a fast or ended early? Record what happened and resume your usual schedule. See why you need not make up hours and how Blimbi saves partial fasts.

Next steps

• Find a fasting schedule for your day

  Answer 3 quick questions and get a fasting schedule to try, with times that fit your day.

• When does my fast end?

  See the time remaining and an educational timeline. Hours on a clock are not a measurement of your body.

• Take the fasting quiz

  A few questions about your day, then a gentle place to start.

• Intermittent fasting protocols

  Compare the common schedules side by side.

Frequently asked questions

What is the best intermittent fasting schedule?

No single schedule has been shown to be best for everyone. Trials generally find similar average effects on weight and many cardiometabolic outcomes across common schedules, so the best one is usually the one you can keep and that fits your health needs.Source 11

Which intermittent fasting schedule is best for weight loss?

None clearly. In a network meta-analysis of 99 randomized trials, only alternate-day fasting lost slightly more than daily calorie restriction (about 1.3 kg), and only in shorter trials.Source 11

Is eating earlier in the day better for blood sugar?

Short trials and timing reviews found better glucose and insulin measures with earlier eating windows, but the evidence is early and varies between studies, so it may not apply to you.Source 22Source 33Source 44

How soon might I notice changes?

Some short trials measured changes in 24-hour glucose or insulin sensitivity within days to weeks. Weight and lasting cardiometabolic changes usually take longer and depend on overall calories, consistency and individual factors.Source 33Source 44Source 11

Is intermittent fasting safe for everyone?

No. If you have diabetes or take glucose-lowering medicine, are pregnant or breastfeeding, have a history of disordered eating or certain medical conditions, talk with a clinician first. Trials differ in monitoring and participants, so tailor any plan to you.Source 11Source 22Source 55Source 66Source 77

Sources

1. 1

   Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trialsZhila Semnani-Azad et al. BMJ, June 18, 2025.DOI: 10.1136/bmj-2024-082007 · PMID: 40533200Systematic review and meta-analysis

2. 2

   Effects of timing and eating duration of time restricted eating on metabolic outcomes: systematic review and network meta-analysisYu-En Chen et al. BMJ, January 21, 2026.DOI: 10.1136/bmjmed-2024-001071 · PMID: 41586347Systematic review and meta-analysis

3. 3

   Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with PrediabetesElizabeth F. Sutton et al. Elsevier BV, June 5, 2018.DOI: 10.1016/j.cmet.2018.04.010 · PMID: 29754952Human randomized trial

4. 4

   Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in HumansHumaira Jamshed et al. MDPI AG, May 30, 2019.DOI: 10.3390/nu11061234 · PMID: 31151228Human randomized trial

5. 5

   Fasting Safely with DiabetesMartin M. Grajower. National Institute of Diabetes and Digestive and Kidney Diseases, August 26, 2020.Official guidance

6. 6

   Weight gain in pregnancyNHS. NHS, July 6, 2022.Official guidance

7. 7

   Overview – Eating disordersNHS. NHS, January 23, 2024.Official guidance