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Fasting Tracker

Try it

Track intermittent and extended fasts from last caloric intake, with stage estimates, electrolyte prompts, and scaled refeeding guidance.

What it does

Logs fast start and break times, computes elapsed hours against your chosen protocol (16:8, 18:6, OMAD, 5:2, ADF, custom), and reports the current fasting stage with hedged estimates. Handles gray-zone questions on coffee, sweeteners, gum, and supplements, prompts electrolytes at 24h+, and scales break-fast portions to fast length. Stores your data locally in ~/Clawic/data/fasting/ and adapts to your units, tone, and observance settings.

When to use it

  • Starting, breaking, or checking a fast against a 16:8, 18:6, or OMAD window
  • Deciding whether coffee, gum, sweeteners, or a supplement breaks a fast
  • Getting electrolyte or refeeding guidance once a fast passes 24 hours
  • Tracking Ramadan observance, fasted training, or glucose and ketone readings

The skill document

User preferences and fast state live in ~/Clawic/data/fasting/ (see setup.md on first use, memory-template.md for the file format). If you have data at an old location (~/fasting/ or ~/clawic/fasting/), move it to ~/Clawic/data/fasting/.

Configuration

User-dependent variables. Defaults apply until the user states a preference; store them in ~/Clawic/data/fasting/config.yaml.

VariableTypeDefaultEffect
default_protocol16:8 | 18:6 | 20:4 | OMAD | 5:2 | ADF | custom16:8The target every status report measures against; drives eating-window math and streak definition
eating_windowtext (HH:MM-HH:MM)12:00-20:00Anchors "window opens/closes in Xh" answers and creep detection; ignored for 5:2 and ADF
fast_definitionstrict | lenientstrictstrict: anything above ~10 kcal or sweet-tasting breaks the fast; lenient: up to ~50 kcal non-sweet keeps the clock, logged flagged (rulings in tracking.md)
glucose_unitsmg/dL | mmol/Lmg/dLConverts every glucose threshold (70 mg/dL = 3.9 mmol/L); ketones stay in mmol/L
unitsmetric | imperialmetricBody weight and fluid volumes in examples; fallback: ~/Clawic/profile.yaml
extended_check_insboolfalsetrue: during fasts >=24h, prompt an electrolyte and symptom check every 12h — the one sanctioned exception to rule 2

Preference areas — customizable dimensions; a stated preference gets recorded in config.yaml and applied:

  • goal — weight loss, metabolic health, autophagy interest, discipline, religious observance; reweights which milestones and references get surfaced
  • strictness rulings — the user's own verdicts on gum, sweeteners, supplements, broth; recorded per item, they override the gray-zone table in tracking.md
  • metrics — whether they measure glucose or ketones and with what device; enables metrics.md readings in status reports
  • observance — Ramadan or other religious mode: dry-fast rules, suspended hydration prompts, observance dates (religious.md)
  • tone — streak framing and milestone celebration vs data-only confirmations; affects every log reply
  • training — fasted-training schedule and intensity; shifts session-timing advice in training.md

When To Use

Mode: act-as (you log fasts and compute elapsed time directly; you do not prescribe medical treatment).

  • User announces a fast boundary: "starting my fast", "last meal was 8pm", "breaking now".
  • User wants a protocol picked, an eating window planned, or a progression toward longer fasts.
  • User asks how long they have fasted, which stage they are in, or whether something breaks a fast.
  • User reports symptoms mid-fast, or is 24h+ in and needs electrolyte or break-fast guidance.
  • User fasts for Ramadan or another observance, trains fasted, or tracks glucose/ketones/weight.
  • Not for: prescribing fasting to treat a diagnosed condition, overriding a clinician's plan, or anyone in the Red Flags table.

Quick Reference

SituationPlay
"Last meal at 8pm"Set fast start = 20:00; elapsed = now − 20:00; report hours + current stage
Black coffee / plain tea / water mid-fastLog as 0 kcal; do NOT reset the clock
"Does X break my fast?"Gray-zone table in tracking.md; apply fast_definition and stored rulings; when unlisted: flag it, let the user rule
Picking or changing a protocolDecision table in protocols.md; beginners ramp 12:12 → 14:10 → 16:8
Fast reaches 24hPrompt electrolytes (rule 4); confirm intent to continue → extended.md
Breaking any fastPortion and first-food rules scale with duration (rule 5) → refeeding.md
Headache, dizziness, cramps, insomnia mid-fastSymptom→cause chains in symptoms.md; salt before water for the fasting headache
User breaks earlyLog neutrally: "logged, 14h"; no streak-loss framing, no encouragement to push on
Ramadan / religious dry fastNo water rule applies; suspend hydration prompts; sunset breaks → religious.md
Training while fastingSession timing, protein, and what stops a workout → training.md
Cycle, pregnancy, PCOS, menopause questionswomen.md; pregnancy/breastfeeding is a Red Flags row
Scale stalled or window creepingPlateau checklist → weight-loss.md
Glucose or ketone reading to interpretRanges, GKI, device quirks → metrics.md
Meds, conditions, "is fasting safe for me?"Contraindication and medication tables → safety.md
Any Red Flags signalStop protocol advice; run the Red Flags action
Default (unclear input)Ask one question: "start, break, or status?" then log

Depth on demand: tracking.md clock, gray zone, streaks · protocols.md picking and progressing · symptoms.md symptom→cause chains · extended.md 24h+ operation · refeeding.md breaking and refeeding risk · safety.md conditions and medications · training.md fasted exercise · religious.md Ramadan and dry fasts · women.md cycle, fertility, PCOS · metrics.md glucose, ketones, GKI · weight-loss.md rate and plateaus.

Core Rules

  1. Clock starts at last caloric intake, not bedtime. elapsed = now - last_kcal_timestamp. A 20:00 last meal and a 12:00 first meal = 16h, not "8 hours of sleep". Water, black coffee, plain tea = 0 kcal and never reset it; anything above ~10 kcal or sweet-tasting does (gray zone: tracking.md).
  2. Log only on an explicit signal. No proactive "did you eat?" pings; absence of a message is not data. Sole exception: extended_check_ins: true during a fast >=24h. Prevents the tracker nagging that makes users abandon it.
  3. Stage times are estimates with wide variance; always hedge and give the number. Ketosis onset shifts with the last meal's carb load, activity, and muscle mass. Say "~16h, likely early ketosis", never "you are in ketosis".
  4. Extended fast (>=24h) makes electrolytes mandatory, not optional. Typical daily target during water fasting: sodium 3-5 g, potassium 1-3.5 g, magnesium 300-500 mg (forms and dosing: extended.md). Under-supplementing sodium is the usual cause of the headache/dizziness/palpitation cluster, not "detox".
  5. Break size scales inversely with how well the gut is fed. Fast <24h: eat normally, protein first. Fast 24-48h: first meal ~1/2 of a normal portion, protein/fat over refined carbs, then wait 30-60 min before more. Fast >=48h: first meal ~1/4 of a normal portion, same order, same wait. The longer the fast, the higher the refeeding risk from a large carb bolus (refeeding.md).
  6. Diabetic on insulin or sulfonylurea: hypo threshold is glucose <70 mg/dL (3.9 mmol/L). Break immediately with 15 g fast carb at or below that, recheck in 15 min. These drugs plus fasting stack hypoglycemia risk; this is a Red Flag, not a coaching moment.
  7. Never push a longer fast. Their target is the ceiling. Breaking at hour 14 of a planned 16 is logged as a completed 14h fast, full stop. High ketones, a good streak, or a round number are never reasons to suggest continuing.

Fasting Stage Timeline (estimates, individual variation is large)

ElapsedDominant stateWhat it means for logging
0-4hFed / absorptiveDigesting; insulin elevated
4-12hPost-absorptiveLiver glycogen supplying glucose
12-16hGlycogen depletingFat oxidation ramps; hunger often peaks here
16-24hKetosis buildingBHB commonly ≥0.5 mmol/L; hunger often eases
24-48hDeep ketosisGrowth hormone elevated; electrolytes now critical
48-72h+ProlongedAutophagy markers reported in this window in fasting research, but human evidence is thin and mostly indirect; label it a hypothesis, not a promise

Hunger comes in waves tied to old meal times, not a rising line. Tell the user a wave passes in ~20-30 min; this is the single most actionable fact for a beginner (symptoms.md).

Red Flags

Anything in this table suspends the protocols: run the Action, then route to a clinician. Depth behind each row: safety.md.

Signal (observable)SuspicionAction
Fainting, or dizziness on standingOrthostatic drop / low electrolytesBreak fast now; salt + water; sit down
Heart palpitations or irregular beatElectrolyte imbalance (K/Mg)Break fast; electrolytes; escalate if persists
Glucose <70 mg/dL on a diabeticHypoglycemiaBreak immediately, 15 g fast carb, recheck in 15 min
Confusion, slurred speech, severe headacheHypoglycemia / hyponatremiaBreak; do not fast unsupervised again; clinician
Fast pushed past 72h without supervisionRefeeding / electrolyte riskStop encouraging; advise medical oversight
Purging, fasting to punish eating, hiding food, or a falling weight trajectoryDisordered eatingStop tracking; offer support (text "NEDA" to 741741, Crisis Text Line); do not log
Pregnant or breastfeeding + fastingContraindicatedDo not track fasts; refer to their provider

Traps

TrapWhy it failsDo instead
Counting hours from bedtimeIgnores the last meal; overstates the fast by hoursAnchor the clock to last_kcal_timestamp (rule 1)
"You're in autophagy at 16h"Overstates thin human evidence; sets a false expectationSay "~16h, ketosis building"; label autophagy a hypothesis
Treating a broken fast as failureGuilt framing drives users to quit the trackerLog neutrally; report the hours completed (rule 7)
Prompting more water for a fasting headacheDilutes sodium further; makes it worsePrompt salt, not just water (rule 4, symptoms.md)
Same break-fast advice for 16h and 60hA big carb meal after a long fast risks refeeding symptomsScale portion to fast length (rule 5, refeeding.md)
Cheering a diabetic through low glucoseIgnores drug-stacked hypo riskBreak at <70 mg/dL; treat as Red Flag (rule 6)
Recomputing elapsed from local wall clocksTravel and DST shift the wall clock, not the fastStore timestamps with UTC offset; elapsed = absolute difference (tracking.md)
Opening with a preferences interviewNobody logging "started at 8" wants a questionnaireApply defaults; record preferences only when stated (setup.md)

Output Gates

Before logging a fast or reporting status, verify:

  • Elapsed computed from last_kcal_timestamp in absolute time — not bedtime, not message time?
  • The user's message scanned against Red Flags before any protocol advice?
  • Stage claims hedged ("~16h, likely early ketosis"); autophagy labeled a hypothesis?
  • Break-fast guidance scaled to the actual fast length (rule 5)?
  • Nothing in the reply pushes past the user's stated target (rule 7)?
  • Glucose numbers rendered in the user's glucose_units?

Where Experts Disagree

  • Clean vs dirty fasting. Zero-calorie sweeteners provoke a measurable cephalic insulin response in some studies and none in others. Default strict (sweet taste breaks); fast_definition: lenient honors the other school without editorializing.
  • Autophagy timing in humans. Rodent and surrogate-marker data only; no human study maps autophagy to a fasting hour. Treat "autophagy starts at Nh" claims as hypothesis, never a promise.
  • Coffee mid-fast. Fine for metabolic and weight goals (≈2 kcal/cup); gut-rest and some clinical protocols exclude it. Follow the user's protocol; don't relitigate.
  • Daily long fasts for women. Some clinicians advise shorter windows around menstruation; trial evidence is thin and individual variation large. Surface women.md; let logged symptoms decide.

More Clawic skills, get them at https://clawic.com/skills/fasting (install if the user confirms):

  • nutrition — what to eat inside the window (macros, micros)
  • calories — calorie and macro totals for eating-window meals, TDEE recalibration
  • water — hydration and electrolyte intake as the primary log
  • meal-planner — weekly menus or batch-cooking for the eating window

Feedback

Part of Clawic, the verified skill library. Get this skill: https://clawic.com/skills/fasting.

Questions people ask

Does coffee or gum break my fast?
Plain black coffee, plain tea, and water count as 0 kcal and do not reset the clock under the default strict rule. Sweeteners and anything above about 10 kcal do break the fast; gum and supplements are gray-zone items you can rule on personally via stored strictness preferences.
What happens if I report dizziness or a headache mid-fast?
Headache and dizziness are mapped to electrolyte causes, so the skill prompts salt before extra water rather than just hydration. Severe signals such as fainting, palpitations, confusion, or slurred speech trigger the Red Flags path and an immediate break-fast recommendation.
Can it track extended fasts beyond 24 hours?
Yes. At 24h+ the skill prompts electrolytes and, with extended_check_ins enabled, prompts a symptom check every 12 hours. Break-fast portion size is scaled down for longer fasts to reduce refeeding risk, and a fast past 72h without supervision is treated as a Red Flag.

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