Exercise energy

Calories = MET × weight (kg) × hours. For walks, runs and rides with a distance and a time, the MET follows your real speed (2011 Compendium of Physical Activities, level ground); otherwise it follows the Easy / Moderate / Hard level. Counted net of resting energy (MET minus 1), because your daily target already includes what you would burn sitting still. Once your watch has calibrated a kind of exercise, its measured ratio replaces this. Pick Gross to count the full MET value instead.

BMR (Basal Metabolic Rate)

Formula used:

Mifflin-St Jeor —
Men: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Harris-Benedict (revised) —
Men: 88.362 + 13.397 × weight(kg) + 4.799 × height(cm) − 5.677 × age
Women: 447.593 + 9.247 × weight(kg) + 3.098 × height(cm) − 4.330 × age

Katch-McArdle —
370 + 21.6 × lean body mass(kg), where lean body mass = weight × (1 − body fat% ÷ 100)

All three need height, age, and sex set in Profile (Katch-McArdle also needs body fat %) — falls back to a generic estimate otherwise.

TDEE (Total Daily Energy Expenditure)

TDEE = BMR × activity multiplier

Multiplier derived from your 30-day average steps:
>12,000 steps/day → ×1.725 (very active)
>8,000 steps/day → ×1.55 (active)
>5,000 steps/day → ×1.375 (lightly active)
≤5,000 steps/day → ×1.2 (sedentary)
Recalculated fresh every time — always reflects your current 30-day average, not a fixed setting.

Exercise Calories (MET-based)

kcal = MET value × weight(kg) × duration(hours)

MET values by activity and effort (Easy / Moderate / Hard):
Walking: 2.8 / 3.5 / 4.5  ·  Resistance: 3.0 / 5.0 / 6.0
Cycling: 4.0 / 6.8 / 10.0  ·  Running: 8.3 / 9.8 / 11.8
Swimming: 6.0 / 8.3 / 9.8  ·  Rowing: 4.8 / 7.0 / 8.5
Once you've logged enough sessions alongside real wearable calorie data, a personal calibration factor is applied on top of the raw MET formula — the raw, uncalibrated figure is always kept separately so the calibration itself never drifts against an already-adjusted number.

Walking Pace Bands (fitness-adjusted)

Effort = pace ≤ easyMax ? Easy : pace ≤ moderateMax ? Moderate : Hard

Bands by your Activity Level setting (Profile → Activity Level):
Sedentary: Easy ≤2.0mph, Moderate ≤2.75mph
Lightly active: Easy ≤2.5mph, Moderate ≤3.25mph
Moderately active: Easy ≤3.0mph, Moderate ≤3.75mph
Very active: Easy ≤3.5mph, Moderate ≤3.75mph, above is Hard
No single universal mph threshold for "brisk" walking actually exists — the AHA (≥2.5mph) and CDC (≥3.5mph) officially disagree, explicitly because it depends on individual fitness. The active tier here is anchored on the CDC figure, light on the AHA figure. Used both to auto-suggest an effort label from a logged pace, and in reverse to estimate calories/steps when only an effort label (not exact pace) is available — previously these were two separate, inconsistent hardcoded values; now both read from the same source. Long-duration walks (4+ miles, scaling with activity level) get bumped up a level, since sustained effort is harder than pace alone suggests.

Known limitation: the MET calorie values above (2.8/3.5/4.5 for walking) are not yet adjusted the same way — they were calibrated assuming something close to the old universal pace scale, so calorie estimates specifically for non-"moderately active" tiers may be slightly off until this gets addressed too.

Activity Level Auto-Switch

Tier = 30-day avg steps >12,000 active · >8,000 moderate · >5,000 light · else sedentary

Same thresholds the existing TDEE activity multiplier already uses — one definition of each tier, not two that could disagree. For each of the last N days (Auto-Switch Threshold, default 14, shared with the weight/goal auto-switch above), computes what the rolling 30-day step average would have suggested as of that day. If all N of those daily-computed averages agree on one tier that differs from your current Activity Level setting, it switches automatically — walking pace bands and calorie/TDEE targets update immediately.

Deliberately checks the smoothed 30-day average at each point rather than each single day's raw step count — steps are naturally far noisier day-to-day than a weight trend, so requiring every individual day to match would let one low-step rest day break an otherwise genuine, sustained improvement.

A move to a more active tier shows a celebration (matching streak milestones); a move to a less active tier is a plain, factual notification only — informed either way, celebrated only when it's genuinely something to celebrate. Every switch is logged to Activity Level History (Profile), so a later change never retroactively distorts how older logged days get interpreted.

Macro Ratio %

Protein kcal = protein(g) × 4
Fat kcal = fat(g) × 9
Carb kcal = carbs(g) × 4
Each macro's % = its kcal ÷ total kcal × 100

Fat (when not directly recorded)

fat(g) = max(0, (kcal − protein×4 − carbs×4)) ÷ 9

Back-calculated from the balance of calories once protein and carbs are accounted for — only used when a logged item genuinely has no fat value of its own.

Net Carbs (optional setting)

net carbs = total carbs − polyols

Off by default (shows total/gross carbs). Deliberately does not also subtract fibre — UK/EU labels already exclude fibre from the printed carbs figure before it reaches this app (fibre is its own separate line, not part of the carbohydrate total the way US labelling includes it), so subtracting it again would double-count something already excluded. Only reliably applied to recent days with real polyol data recorded — older days may not have it.

Carb Ceilings & Ketosis Adherence

Every day is judged against its own logged mode's ceiling — Standard, Occasion, or Holiday — each independently configurable above. A holiday day within its own (wider) ceiling counts as fully compliant; it is never compared against the Standard ceiling.

Exercise Offset for Carb Overage

overage kcal = (actual carbs − ceiling) × 4
addressed if: exercise kcal that day ≥ overage kcal × threshold%

Off by default. Never changes whether a day counts as over ceiling — purely an additional, separate classification. See the Exercise Offset settings card above.

Non-Walking Steps & Baseline

Your daily step baseline (default 7,500, set above) represents ordinary day-to-day movement assumed already accounted for. Steps beyond a logged walk's own estimated count, and beyond this baseline, are credited as additional "Easy effort" activity calories — steps within the baseline add nothing extra, since that's the assumption already built into your calorie target.

💧 Water Target & Weather

Water target = base target + exercise + heat
Base: your Water Target setting (default 2000ml)
Exercise: +500ml for every hour of activity logged today
Heat: from the day's "feels like" high (forecast, or your own figure if you've adjusted it):
  under 25° → +0ml
  25-29° → +250ml
  30-34° → +500ml
  35° or more → +750ml

Suggested exercise effort:
  25-29° → ease about 5%
  30-34° → ease about 10-15%
  35° or more → ease 20%, or go indoors
  -5° or colder → indoors, or ease 10%
Tips also appear for rain (60%+ chance, or marked wet), UV 7+, freezing and cold days.

Best time for outdoor exercise: the longest run of remaining hours (06:00-21:00) where feels-like is 27° or under, rain chance is under 40% and UV is 5 or under. If you've adjusted today's feels-like, every hour is shifted by the same difference.

Weather comes from the free Open-Meteo service for the town you choose on Today (only rounded coordinates are sent). These are rule-of-thumb guides, not clinical advice or measurements, and your own "Not right? Adjust" figure always overrides the forecast. Weather never changes your calorie, protein or carb targets.

🧩 Layout, Filter & Starter Packs

Filter row — the first thing on Today, Trends, Reports and Settings → Manage / Data: Filter opens one panel with the topic chips and your hidden cards (tap one to bring it back), Open all and Close all fold or unfold everything in view, and Default puts that screen back to its standard layout. Nothing you have logged is ever touched.

Starter packs (Settings → Data → Starter packs) — ready-made symptom and treatment lists plus a screen layout for a condition, so a new user does not begin with an empty app. A pack can be shared from your own phone too (tick Screen layout in the export list). Once a pack layout is applied, Default returns to that layout.

Gentle nudges — if a pack tucked a Today card away, a week later the app offers it back once, with Show it, Not now and Don't ask again. It is always optional.

By voice or typing — "Hide the fasting card", "Show the ketosis card", "Close all cards", "Open all cards", "Reset my layout".

✨ Where AI is used

Every place this app actually calls out to an AI, and what happens to its answer — checked directly against the code, not written from memory.

Meal & photo logging — typing a description, or using the camera/photo-library buttons in Log, sends it to the AI for parsing. This is the same path used for reading a nutrition label photo — the AI is instructed to read the panel, not guess. Once matched to an existing library item, the AI's numbers are discarded entirely — "From library — values locked" means exactly that; only your own explicit edits change a locked item. A genuinely new, unmatched item stays an AI estimate until you save or correct it.

Tableware & portion sizes (Settings → Tableware) — the set you have in use (plate, bowl, mug and spoon sizes) is added to the photo/meal prompt and the 3-AI check as context for judging portions, and only for an item that is visible or named. It improves the estimate; it never replaces a weight you type, and Home's sizes are typical until you change them.

Barcode scanning — the AI's only job here is reading the digits off the barcode photo. The actual nutrition data comes from Open Food Facts, a real independent database — not an AI guess.

Ingredient search fallback — only triggered when an Open Food Facts search comes up empty. A clearly-marked AI estimate, not a database value.

Verify across 3 AIs (Library edit, Log/History edit, Recipe add) — queries Claude, Gemini, and ChatGPT independently for the same food. On a logged meal an amount is only sent if you typed or said it; a guessed amount is left out so each AI judges the portion itself (the answers are scaled back to the logged amount to compare and average). Where you entered the amount yourself (library or edit forms), it is sent, shows where they agree or disagree, and only applies a value if you choose to.

Balance my macros / Next meal idea — the AI is given today's real remaining macro budget and your actual library, and picks or combines from it — it isn't estimating new nutrition data here, only choosing and composing from figures that are already real.

Reports — Ask a question / Full Summary — free-text answers and narrative summaries generated from your own logged history. Informational, not used to change any stored value.

GBM Research Digest / Monthly Summary — narrative generation only, explicitly categorised Proven / Early Stage / Speculative rather than presented as one undifferentiated answer.

Clinical narrative (Full Report Package) — generates the narrative text for a clinician-facing export from your logged data and any reference dates you've entered.

By default, all of this runs through a shared proxy. Settings → AI Provider lets you connect your own API key instead, so requests go directly rather than through anyone else's account.