Updated 1 week ago Science

What is active energy burned and how it's calculated

Active energy burned measures how many calories a user burns from physical activity (above resting). Learn how to interpret Sahha’s active_energy_burned biomarker and use it in your product.

Active energy burned is the estimated energy a user expends from movement and exercise, above their baseline resting needs. It’s commonly expressed in kilocalories (kcal). Higher values usually indicate more total physical effort for the day (longer duration, higher intensity, or both).

Key Takeaways

  • What it measures: calories burned from activity (above resting metabolism).
  • Why it matters: it’s a practical “effort proxy” that complements steps and active minutes.
  • How to use it: power effort-based goals, explain activity score changes, and personalize pacing/recovery.
  • Best practice: treat it as an estimate, use trends and baselines, and avoid precise claims.

Metric Spec

ItemValue
Sahha field nameactive_energy_burned
What it representsEnergy expended from physical activity above resting baseline
UnitKilocalories (kcal)
Typical cadenceDaily (daily)
AggregationTotal (total)
Data requirementsSource-dependent; estimates are more reliable with wearable heart rate + motion
Best used forEffort-based goals, intensity context, pacing/recovery personalization, driver explanations

What Is Active Energy Burned?

Active energy burned refers to energy used for physical activity — walking, workouts, climbing stairs, sport, etc. It excludes the energy your body uses just to stay alive at rest (often called resting energy or basal metabolic needs).

A useful mental model:

  • Active energy = “extra energy from movement”
  • Resting energy = “background energy to run the body”
  • Total energy = “active + resting”

Why Active Energy Burned Matters

Active energy is valuable because it captures something steps can miss:

  • two users can have similar steps but very different effort (pace, hills, carrying loads)
  • cycling, rowing, or gym training can have low steps but high activity energy
  • it aligns naturally with how users think about “how hard did I go today?”

Product takeaway: active energy burned is a strong effort signal — great for coaching that adapts to how demanding the day was.

How Sahha Represents Active Energy Burned

Sahha provides active energy burned as an Activity biomarker:

  • Biomarker: active_energy_burned
  • Unit: kcal
  • Periodicity: daily
  • Aggregation: total
  • Description: estimated energy burned from activity

Example biomarker object:

{
  "name": "active_energy_burned",
  "value": 420,
  "unit": "kcal",
  "periodicity": "daily",
  "aggregation": "total"
}

Active energy burned can also contribute to higher-level outputs like Activity Score and Wellbeing Score alongside steps, active duration, and intensity durations.

How to Interpret Active Energy Burned

  • Higher than baseline: more total effort (longer activity, higher intensity, more elevation, or all three).
  • Lower than baseline: less total effort that day.
  • High active duration + low active energy: likely lighter movement (walking, light chores).
  • Low active duration + high active energy: concentrated intense session (hard workout).

Use baselines, not rigid targets

Energy expenditure estimates vary by:

  • device and algorithm
  • whether heart rate is available
  • body size assumptions and calibration
  • whether the device was worn consistently

Treat the value as an estimate and focus on trends and relative changes.

How to Use Active Energy Burned in Your Product

1) Effort-based goals (more inclusive than steps)

Examples:

  • “Hit your usual effort range today”
  • “Add +50 kcal above your baseline”
  • “Effort streak (3 days this week)”

These work well for users whose movement isn’t step-heavy (cycling, gym, sport).

2) “Push vs recover” personalization

If active energy is high, consider:

  • softer tone
  • recovery suggestions
  • reduced intensity nudges the next day (especially if sleep debt is high)

3) Better explanations for activity scores

Driver card pattern:

  • “Your steps were similar, but your activity effort (active energy) was lower — that’s why your activity score dipped.”

4) Pair with intensity durations

Active energy becomes more interpretable when paired with:

  • activity_medium_intensity_duration
  • activity_high_intensity_duration

This allows guidance like:

  • “You had less vigorous time today, so your effort was lower.”

Implementation Suggestions for your Products

  1. Prefer trends over single days

    • Daily energy can swing a lot; weekly averages are more stable.

  2. Explain uncertainty

    • Use language like “estimated” and “about” to avoid false precision.

  3. Design for coverage

    • If the user doesn’t wear their device consistently, energy can undercount. Handle missing/low-confidence days gracefully.

  4. Use simple decision rules Examples:

    • If active energy is high + sleep debt is high → recommend recovery
    • If active energy is trending down → suggest a low-friction movement plan
    • If active energy rises week-over-week → celebrate effort consistency

FAQ

Is active energy the same as total calories burned?

No. Active energy is only the calories burned from activity above resting needs. Total energy includes resting energy as well.

Why does my active energy look high when my steps are low?

Non-step activities (cycling, gym training, sport) can burn substantial energy without producing many steps. Wearables also capture effort via heart rate when available.

Why is my value missing (null)?

Some sources don’t provide active energy, permissions may not be granted, or device wear time may be insufficient. Build your UI to degrade gracefully.

Can active energy burned be inaccurate?

Yes. It’s an estimate and can vary by device, algorithm, heart rate availability, and wear consistency. Use it as a trend and effort proxy, not a precise calorie counter.

  • Total energy burned: total_energy_burned
  • Active duration: active_duration
  • Active hours: active_hours
  • Steps: steps
  • Floors climbed: floors_climbed
  • Intensity durations: activity_low_intensity_duration, activity_medium_intensity_duration, activity_high_intensity_duration

Notes

This content is educational and designed for product personalization and engagement. It is not medical advice.

References

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