Burn Help & Guide

Everything you need to know about tracking your fasts, your weight, and your BMI in Burn.

iOS & Android $0.99 one‑time No account needed
Getting started

Set up Burn in three steps

Burn only needs a couple of details before it can start tracking your fasting window.

  1. Set your fasting goal

    Open the Profile tab and choose how many hours you're aiming to fast — 16 hours is the default, but you can change it any time.

  2. Log your first weight entry

    Head to Log weight, enter today's date and weight in pounds, and tap Log weight to save it.

Dashboard

Reading the fasting ring

The Dashboard is where you start and end a fast, and see how today is going at a glance.

0h 17m
of 16h goal
FED STATE
  • RingFills in as your fast progresses toward your goal. The dot at the top marks the start/end switch — tap it to begin or end a fast.
  • Stage tagShows which of the four fasting stages you're currently in (see below).
  • StreakCounts consecutive days you've completed a fast that reached your goal.
  • Ends atThe clock time your current fast will hit its goal.
  • TotalHours fasted so far this week, added up across all sessions.
  • End fastStops the timer and logs the session — you can do this before or after reaching your goal.
Fasting stages

The four stages Burn tracks

As your fasting window gets longer, your body moves through recognizable stages. Burn's ring tag tells you which one you're in right now.

16h typical goal FED STATE POST-ABSORPTIVE FAT BURNING KETOSIS

Fed state

0–4 hours

Right after eating. Your body is actively digesting and using glucose from your last meal for energy.

Post‑absorptive

4–16 hours

Digestion has finished and blood sugar starts to drop, so your body begins tapping stored glycogen.

Fat burning

16–24 hours

Glycogen stores run low and your body shifts toward burning stored fat for energy.

Ketosis

24+ hours

With fat as the main fuel source, your liver produces ketones your body can use for energy.

These stages are general guidance built into the app, not medical advice. If you're new to fasting or have a health condition, check with a doctor before starting an extended fast.

Weight & BMI

Logging weight and reading your chart

Burn keeps a running history of your weigh‑ins and turns it into a trend line automatically.

Log weight tab

DateDefaults to today; edit it to back-log a past weigh-in.
Weight (lb)Enter your current weight, then tap Log weight to save.

Chart tab

CurrentYour most recent weigh‑in and calculated BMI.
Trend linePlots your last 14 or 30 entries depending on how much history you have.
Profile

Your personal data

Everything Burn uses to personalize your fasting goal and BMI calculation lives in one place.

ThemeChoose the app's color style — Classic is the default fire theme.
Height (ft / in)Used for your BMI calculation — enter feet and inches separately.
Fasting goalThe target hours your Dashboard ring counts toward, e.g. 16 hours.
NotificationsGet a local alert the moment you hit your fasting goal. Turn off anytime — no need to touch system settings.
Save profileApplies any changes you've made above.

Reset all data permanently deletes every weigh‑in and fast, and resets your profile to defaults. This can't be undone, so use it only if you want a clean slate.

FAQ

Common questions

Where is my data stored?
All of your fasting sessions, weigh‑ins, and profile details are stored on your device. Burn doesn't require an account or send your data anywhere.
Can I change my fasting goal mid‑fast?
Yes. Updating the fasting goal in Profile changes the target your current and future fasts count toward — your ring will reflect it immediately.
What if I forget to end a fast?
You can end it whenever you next open the app — Burn logs the actual duration up to the moment you tap End fast, not a preset window.
How is BMI calculated?
Burn uses the standard BMI formula — weight divided by height squared — based on the height you've entered in Profile and your most recent weight from Log weight.
Can I edit or delete a past weigh‑in?
You can log a corrected entry for the same date at any time from Log weight — the chart uses your most recent entry per day.
I want to start over. What does Reset all data do?
It permanently clears every fast and weigh‑in and returns your profile to its defaults. There's no undo, so only use it if you're sure.
Will Burn notify me when my fast is done?
Yes, if you leave Notifications on in Profile — Burn sends a local alert the moment you hit your fasting goal. The first time it's turned on, your phone will ask for notification permission; if you decline or turn the setting off later, Burn simply won't send it.