How does Calibrated Energy work?

Calibrated Energy estimates your total daily energy expenditure, sometimes called TDEE: the energy you burn each day, exercise included, estimated from your food logs and weigh-ins. It's included with Foodnoms+.

Rather than a black box, calibration is a calculation you can inspect. This article explains what data is used, how the estimate is checked, and how changes reach your goals.

This article uses calories throughout. If your energy unit is kilojoules, everything works the same way and is shown in kilojoules.

How It Works

Weight change comes down to energy balance, often called calories in, calories out (CICO): burn more than you eat and your weight trends down; burn less and it trends up. Flip that around, and your weight trend becomes an answer key. Suppose you log an average of 2,400 calories per day for a month:

• If your weight held steady, you burn about 2,400 calories a day.

• If you lost weight, you burn more than 2,400. The loss reveals how much more: each kilogram of body weight represents roughly 7,700 calories (about 3,500 per pound).

• If you gained weight, you burn less than 2,400, by the same math.

Calibration runs this calculation on your real data: your estimated daily burn is your average daily intake, minus the daily energy value of your weight trend. Formulas describe the average person with your stats; this estimate describes you.

This energy-balance approach builds on peer-reviewed research showing that math over repeated weigh-ins can track long-term energy balance about as accurately as gold-standard laboratory methods (Sanghvi et al., 2015, American Journal of Clinical Nutrition).

What Data Is Used

Each calibration looks at your most recent 28 days of data (sometimes longer; see the next section).

Your Food Log. Your daily calories are averaged across fully logged days. Days that look only partially logged, well below your typical day, would drag the average down and make your burn look smaller than it is, so they're set aside automatically. During a calibration you can review those days and include or exclude them yourself.

Your weigh-ins. Scale weight bounces around daily with water, sodium, and timing, so no single weigh-in is taken at face value. Obvious outliers that don't fit the surrounding readings, like a typo, are excluded from the trend (they appear dimmed on the chart). The remaining weigh-ins are smoothed over a 7-day span, and a trend line is fitted through the smoothed values to find your true rate of change. You don't need to weigh in daily; a few times a week works well.

How the Estimate Is Checked

A trend line can be misleading: a water-weight dip that rebounds, a long weigh-in gap, or readings clustered at one end of the window can all distort your apparent rate of change. So before trusting the recent trend, calibration puts it in context:

• The same estimate is computed over longer spans (35 and 42 days). When all three agree, the recent trend is corroborated: your last four weeks tell the same story as your last six, and the 28-day estimate stands.

• When they disagree, something changed recently. That's often good news, like progress that just started, but it can also be a temporary swing, like water weight, that a longer view would average away.

• To tell those apart, calibration checks where your weight sat just before the window. If your weight genuinely moved away from where it started, the recent trend is real and is kept, even when it's fast. If you ended the period about where you started, it was a round trip, and the longer view is used instead.

• Patterns like a dip-and-rebound, or a swing too fast to be lasting change, are called out in plain language during the calibration, so you know what was seen and what the calculation did about it.

• Estimates below 800 or above 6,000 calories per day are considered implausible and are never offered.

When the data is genuinely ambiguous, for example after a long weigh-in gap, the calibration says so plainly, shows the evidence on the chart, and suggests improving the data first. You can still apply the estimate; the recommendation just errs on the side of caution.

How Changes Are Applied

When a new estimate is ready, review it and the data behind it, then apply it in one tap. Nothing changes on its own, and the recommendation is deliberately conservative:

• Big changes ease in. If the estimate is far from your current value (more than about 10%), or the data is on the sparse side, the recommendation moves about halfway there. The next calibration closes more of the gap as the data firms up.

• One calibration never moves your value by more than 400 calories. Larger jumps are almost always a data artifact rather than a real metabolic shift, and the weekly cadence means any error is short-lived.

• Tiny differences are ignored. Within about 75 calories of your current value is within the noise, so the calibration confirms your current number rather than chasing the wiggle.

You always see the full estimate and can choose it directly if you prefer.

Applying a calibration updates your energy expenditure from that day forward, keeping your automatic calorie goal in sync; past days keep the values that were in effect at the time. Calorie goals never drop below a safe minimum, regardless of the estimate.

Between calibrations, your number stays steady. It doesn't move with daily Apple Health activity readings: your 28 days of data already include all of your activity, averaged over real weeks of living.

Unlocking Your First Calibration

A reliable estimate needs enough data: log your meals on at least 14 of the last 28 days, and weigh in across at least a week, with a recent weigh-in. The Calibrated Energy screen shows how close you are. After your first calibration, a new one opens every 7 days.

If your weight is below the healthy range for your height, a lower calorie target isn't suggested; consider talking with a healthcare professional.

Getting the Best Results

Consistency matters more than perfection. Calibration estimates the relationship between what you log and what your weight does, so if you always log the same way, even imperfectly, the estimate stays right in your terms. What throws it off is a change in logging habits, like stopping use of a food scale or a vacation of unlogged meals; expect a calibration or two before the number settles again.

Log most days, weigh in a few times a week, and don't worry about single odd readings. The smoothing and outlier handling exist so you don't have to curate your data.

When the Estimate Can Be Off

Calibration has two inputs: what you log and what the scale says. Anything that changes one of them without your metabolism changing can push the estimate off. These are the cases worth knowing:

Your logging changed, not your metabolism. This is the most common one. From the inside, a shift in how accurately you log looks exactly like a shift in how much you burn, because both change the relationship between your logs and your weight. If a calibration moves and nothing about your body did, think back to whether your logging changed: a food scale set aside, a stretch of estimated restaurant meals, a week of untracked snacks.

Your most recent weigh-in was a typo. Odd readings are normally caught by comparing them with the readings around them, but the newest one has nothing after it to compare against yet. If your latest weigh-in is wrong, correct it before calibrating.

Something disrupted the whole period. Illness, travel, or a long break from logging can affect several weeks at once, which is more than the cross-checks can look past. After a disruption like that, expect a calibration or two before the number settles.

In all of these, the guardrails still apply: no single calibration moves your value by more than 400 calories, calibrations are weekly, and each new one corrects the last. An estimate that drifts wrong gets pulled back as soon as your data returns to normal.

Getting Started

In Foodnoms settings, select Body Profile, then turn on Calibrated Energy. It's available on iPhone, iPad, and Mac.

Calibrated Energy provides estimates for general wellness, not medical advice. Check with your doctor before making significant changes to your diet.