# Intermittent Fasting Planner

Plan a 16:8, 18:6, 20:4, OMAD or custom fast: enter your last meal time and get a color-coded 24-hour timeline plus hour-by-hour milestones (metabolic switch, fat-burning, ketosis, autophagy) as concrete clock times.

> Canonical page: https://elysiatools.com/en/tools/intermittent-fasting-planner

- **Category:** Health

- **Keywords:** intermittent fasting, fasting planner, 16:8, 18:6, omad, fasting timeline, eating window, autophagy

## Overview

Enter when your last meal was and this planner computes your whole fast: when the eating window opens and closes, and when each metabolic phase transition happens — the post-absorptive state, glycogen draw, the ~12h metabolic switch into gluconeogenesis and early ketones, fat-burning mode with early autophagy (16–24h), the ketosis shift (24–48h), and the peak autophagy zone (48–72h). The result is a printable, color-coded timeline (one row per day), a milestone table with real clock times you can set reminders for, and a copyable plain-text schedule. Six presets cover 12:12, 14:10, 16:8, 18:6, 20:4 and OMAD; the custom option supports any window from 2 hours up to a 72-hour extended fast. Phase onsets follow the widely-published fasting-stage model and are approximate — informational only, not medical advice.

## Inputs

- **Fasting plan** (select)
- **Custom fast length** (number)
- **Last meal time (HH:MM)** (text): e.g. 19:00

## When to use

- Establishing a daily intermittent fasting routine such as 16:8, 18:6, 20:4, or OMAD around variable dinner times.
- Mapping estimated physiological phases—like the metabolic switch, fat oxidation, ketosis, and peak autophagy—onto concrete clock times.
- Scheduling multi-day extended fasts up to 72 hours with clear milestones and refeed target times.

## How it works

- Select a standard intermittent fasting protocol (12:12, 14:10, 16:8, 18:6, 20:4, OMAD) or choose custom to specify duration from 2 to 72 hours.
- Enter the exact time you finished your last meal using 24-hour format (HH:MM).
- Review the generated 24-hour visual timeline, milestone transition table with clock times, and copyable text schedule.

## Use cases

- Aligning work schedules and family dinners with an 8-hour or 4-hour daytime eating window.
- Setting exact phone reminders and alarms for key fasting milestones like the 12-hour metabolic switch or the 16-hour fasting goal.
- Planning a safe 48-hour or 72-hour extended water fast with mapped stages and an exact planned refeed time.

## Frequently asked questions

### What protocols does the intermittent fasting planner support?

It provides presets for 12:12, 14:10, 16:8, 18:6, 20:4, and OMAD (23:1), alongside a custom option covering any duration between 2 and 72 hours.

### How are metabolic milestones such as fat-burning and autophagy determined?

Milestones are estimated using standard fasting science models (~12h for glycogen depletion and metabolic switch, 16–24h for enhanced fat burning and early autophagy, 24–48h for ketosis, and 48–72h for peak autophagy).

### Can I plan an extended fast lasting multiple days?

Yes, select 'Custom fast length' and set the duration between 2 and 72 hours to generate a multi-day timeline and milestone breakdown.

### What format should I enter for my last meal time?

Enter the time in a standard 24-hour HH:MM format, such as 19:00 for 7:00 PM or 20:30 for 8:30 PM.

### Is the schedule output medical advice?

No, metabolic phase timing and visual schedules are informational estimates based on published physiological stages and do not replace personalized medical advice.

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