Body Insights turns Apple Health data into scores, trends, and plain-language guidance. This library gives every user-visible calculation its own page, so you can see what it reads, how missing data is handled, and what the result cannot tell you.
These pages explain the method without publishing proprietary weights, gameable thresholds, or medical claims the data cannot support.
Sleep and timing
How Light Exposure Is Calculated
Body Insights totals supported ambient-light or daylight exposure within the relevant daily windows and relates timing to the estimated circadian phase. Light prescriptions use bedtime, wake time, phase, and adaptation context.
How Metabolic Sleep Is Calculated
Body Insights aligns compatible CGM readings with the recorded sleep session, then derives supported stability, variability, peaks, dips, and directional patterns. The summary depends on adequate coverage of the same night.
How Overnight Recovery Is Read
Body Insights reads overnight HRV, sleeping heart rate, heart-rate dip, respiratory and oxygen context when available, then compares those signals with your own history. It treats missing sensors as missing, not as poor recovery.
How Your Body Clock Is Estimated
Body Insights estimates circadian phase from recent sleep timing, sleep midpoint, chronotype context, wake patterns, and light information when available. It then derives practical timing windows from that estimate.
How Your Sleep Debt Is Calculated
Body Insights compares your nightly sleep target with valid recorded sleep, accumulates recent shortfalls across its active window, and uses that estimate to shape a recovery plan. Extra sleep can reduce the estimate without promising instant recovery.
How Your Sleep Score Is Calculated
Body Insights calculates its own sleep score from duration, stage structure, awake time, continuity, and efficiency, then reads that night against your personal history. It does not reuse Apple's finished Sleep Score.
What Shapes Your Sleep Quality
Body Insights reads sleep efficiency, stage balance, awakenings, fragmentation, regularity, and timing alongside total sleep. No single stage is allowed to tell the whole story.
Recovery, stress, and energy
How Acute Stress Is Detected
Body Insights derives RMSSD from usable beat-to-beat intervals in a supported ECG recording, checks signal quality, and compares the result with your established range. A meaningful downward deviation can surface an acute-strain marker.
How Burnout Risk Is Calculated
The Burnout Risk calculation summarizes supported longer-term HRV direction, recovery nights, stress and recovery behavior across its active trend window. It is distinct from the self-reported Life Balance score.
How Nervous System Age Is Estimated
Body Insights compares supported HRV and resting-heart-rate patterns with age-related reference data, then expresses the relative pattern as an age-like estimate. Your own trend remains more useful than the label alone.
How Stress Balance Is Calculated
Body Insights reads HRV, resting heart rate, sleep and recent trend context against your personal baseline. The score summarizes physiological strain and recovery balance, not your emotions.
How Waking Recovery Is Calculated
Waking Recovery uses the readiness calculation built from available autonomic, sleep, training, circadian, and metabolic context. Data freshness and safety coverage change the guidance, not a second hidden score.
How Your Body Battery Works
Body Insights combines supported sleep, autonomic recovery, stress direction, activity, and recent load into a bounded energy estimate. It emphasizes your personal trend rather than a universal athlete target.
How Your Life Balance Score Works
Body Insights scores the completed questionnaire across its supported life domains and summarizes the pattern into an overall balance view. It does not feed those answers into the physiological Burnout Risk formula.
How Your Readiness Score Works
Body Insights combines supported autonomic, sleep, training, circadian, and metabolic components, then normalizes across the components actually available. Today's Capacity uses this same result; safety and freshness change the guidance around it.
How Your Resilience Score Works
Body Insights combines supported Mind and Body recovery signals, including HRV direction and recovery behavior after detected stress events. The result summarizes adaptability across recent history.
Fitness and cardiovascular
How Cardio Adaptability Is Read
Body Insights derives adaptability context from supported heart-rate response, movement or pace, recovery, and personal trend signals. It compares like activities and conditions where the available data permits.
How Post-Workout Recovery Is Read
Body Insights aligns supported post-workout heart-rate recovery, HRV response, glucose context, and workout load, then compares those signals with your recent history. Each row remains visible because the signals are not interchangeable.
How Steps Become a Long-Term Signal
Body Insights aggregates valid Apple Health step totals across the selected window, shows direction and consistency, and translates the pattern into longevity context and an age-like comparison where supported.
How Your Fitness Age Is Calculated
Body Insights uses your profile and available Apple Health cardio-fitness estimate with an established fitness-age relationship to produce an age-like comparison. The estimate is only as reliable as the underlying profile and VO2 max data.
How Your Fitness Summary Works
The headline fitness gauge reflects your available cardio-fitness or VO2 tier rather than a hidden weighted average of every card. Steps, workouts, load, zones, and recovery keep their own calculations.
How Your Heart Rate Metrics Work
Body Insights reads supported heart-rate samples from Apple Health, groups them into the relevant time window, and derives personal baselines, zones, and context-specific ratios where required. Manual maximum heart rate can update dependent zone calculations.
How Your Training Load Is Calculated
Body Insights estimates session load from workout intensity and duration, then rolls valid sessions into short- and longer-term load views. Derived balance and recovery-risk signals compare those windows without treating them as injury predictions.
Glucose, metabolism, and fasting
How Fasting Readiness Is Calculated
Body Insights combines supported recent recovery, sleep, glucose, fasting history, and safety context to estimate whether a planned fast looks more or less supported. Session progress and metabolic flexibility are calculated separately from actual completed sessions.
How Metabolic Readiness Is Read
Body Insights reads overnight glucose stability, variability, and usable coverage during the sleep window. When that component is supported, it can add metabolic context to readiness; when it is absent, readiness is normalized without it.
How Workout Glucose Response Is Read
Body Insights aligns usable CGM readings with the workout start, duration, and recovery window, then shows direction, change, and delayed patterns where coverage supports them.
How Your Glucose Overview Is Calculated
Body Insights groups valid glucose readings into the selected local day, then calculates supported summaries such as average, minimum, maximum, range, and visible trend. It reads compatible CGM data from Apple Health; it does not measure glucose itself.
Risk, reports, and personal context
How Genetic Insight Scores Work
Body Insights maps supported imported variants to trait rules and aggregates only covered evidence into category views. Categories with no covered variants are excluded from the headline rather than treated as reassuring. These pages describe predisposition, not destiny.
How Health Anomalies Are Detected
Body Insights evaluates supported current signals against personal history and flags observations or combinations that are sufficiently unusual for that context. The detector identifies difference, not diagnosis.
How Illness Risk Is Estimated
Body Insights looks for supported deviations in HRV, resting heart rate, respiratory rate, temperature, sleep, and symptom context relative to your personal baseline. Several aligned changes can raise the illness-risk estimate.
How Your Monthly Health Audit Works
Body Insights groups each supported metric into the calendar month, calculates its own valid-day or valid-night summary, compares the result with prior context, and selects the clearest changes for the report.
How Your Morning Report Is Built
Body Insights gathers supported sleep, recovery, readiness, stress, energy, and anomaly results, then selects the clearest current explanations for the morning. Each metric keeps its own calculation and methodology page.
Start with the card in front of you
Tap the information button on a supported card in Body Insights to open its exact calculation page. If a page is still under source or product review, the in-app link stays disabled through Remote Config until that explanation is approved and deployed.