Body Battery is a 0-100% energy reserve that rises and falls through the day. Sleep charges it, effort drains it and calm moments give some back, so at any point you can see how much you have left in the tank and what used it up.
The Body Battery card on the Dashboard draws your energy reserve as a curve across the day. Alongside it you see where you are Now (or at End of day for a past day), your Peak and Low, and how much you Charged and Drained in total. Unlike Recovery, which is set once in the morning, Body Battery keeps moving as you go about your day.
The app explains what moves it in four plain rules:
Most people judge their energy by feel, and feel is easily fooled by coffee, adrenaline or a deadline. A reserve that follows your body's actual load gives you a second opinion. It helps answer practical questions: do I have enough left for an evening workout, or should I keep it easy? Why am I flat by mid-afternoon on some days and not others?
It also shows how connected rest and effort are. A short or restless night means you start the day with less. A day of back-to-back meetings with no breaks, or a hard session on top of a busy schedule, drains you faster. A walk, a quiet lunch or a few minutes of slow breathing can give a little back. Seeing that play out on your own curve makes it easier to plan days that leave something in reserve, which in turn sets you up for a better night.
Tap the card for an interactive day curve you can scrub to see your reserve at any point. What Moved It lists your Biggest gains and Biggest costs, so you can tell whether it was the night, the workout or a long stressful stretch that drained you.
Last 7 Days shows a range bar for each day: each bar spans that day's lowest to highest reserve and a dot marks where the day ended, with your average peak alongside. A week of low ceilings usually points back to sleep or recovery; a week of deep dips points to load.
Body Battery needs continuous heart rate and sleep from your watch, so wear it overnight and through the day. Data from other devices or apps that save to Apple Health counts too.
Beyond the Dashboard, Body Battery is on the Today page of the FitRest Apple Watch app with a Last 24 Hours curve, as a watch complication, as Small and Last 24 Hours iPhone widgets, and as a Lock Screen widget.
Yes. FitRest gives Apple Watch users a Body Battery that shows your energy reserve through the day, on iPhone, on the watch and in widgets and complications.
Yes. FitRest builds Body Battery from the heart rate and sleep your Apple Watch saves to Apple Health, and shows it on iPhone, in widgets and on the watch.
Your Recovery score sets the ceiling for the day, so a poor night cannot charge you to 100 however long you stay in bed.
Recovery is a single morning verdict on last night. Body Battery starts from that night and keeps moving through the day as effort drains it and rest tops it up.
Stress and busy stretches raise your heart rate above resting too, and that draws on the reserve. Calm periods give a little back.
A 0-100 readiness score each morning that tells you how well your body recovered overnight, judged against your own normal.
A 0-100 reading of the physical stress your body is carrying, with a 24-hour curve and a longer-term trend.
A 0-100 score for each night's sleep, with a label, a comparison with your recent average and the factor that held it back.
38 Home Screen and Lock Screen widgets for scores, heart, steps and logs, including an interactive water quick-add.
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FitRest reads the data already in Apple Health, so there is nothing to set up beyond granting access.
iPhone, iPad and Apple Watch. Requires iOS 17 or later.