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NewiOS 26 · watchOS 11 · works with any LLM

The First App
Built for Your Liver.

Track fasting, log your labs, and copy a one-tap prompt for any LLM — built for NAFLD/MASLD, 100% private.

Get the App — $39.99Read Mark's Story →
Works with Apple Health
No subscriptionsNo adsApple Private CloudKitNo data collection
Personalized review
One tap to copy your full health context.

Bundles labs, fasting, HealthKit, and body metrics into a prompt for any LLM.

Private by design
Your data stays in CloudKit Private DB.

Not on our servers. We literally can't see it.

LivaFast app fasting screen
Bring your own LLM
Paste into Claude, ChatGPT, Gemini, Grok.

The app never calls a model itself. You choose where the prompt goes — and what it sees.

Clinical metrics
FIB-4, ALT, AST, GGT. The numbers your hepatologist uses.

Track lab trends between appointments.

Why it matters

Fatty liver disease is silent, common, and poorly served by existing fasting apps.

38%of adults globally have NAFLD/MASLD — now the most common liver condition on earth.Source · Lancet 2024
1 in 3people with fatty liver have no idea they have it. Most discover it by accident.Source · AASLD guidelines
<5 minis how much time most top-ten fasting apps devote to liver health — combined.Source · our audit, Mar 2026
What's inside

Thirteen tools. One liver. No fluff.

LivaFast is a focused workbench for people managing MASLD — not a general wellness app. Every feature earns its place by answering a clinical question.

Personalized review
01

Personalized review prompt

One tap copies a structured prompt with every lab value, fasting session, HealthKit signal, and body metric the app has logged — ready to paste into any LLM you trust.

  • Full health context, not a single computed number
  • Paste into Claude, ChatGPT, Gemini, Grok, or any LLM
  • Tap any included section to see what made it in
Personalized review prompt screen
01 / 13
Personalized review

Get a personalized review from any LLM.

The app already records every lab value, fasting session, exercise minute, sleep window, and body-composition reading you’ve logged. With one tap, LivaFast bundles all of it into a single, structured prompt — formatted for any LLM — and copies it to your clipboard. Paste into Claude, ChatGPT, Gemini, Grok, or whichever model you trust, and get a review grounded in your complete history.

No more pasting lab results one row at a time, no more re-typing your fasting schedule. And because a frontier LLM gets your full context — not just a single number — the review is sharper, more specific, and more useful than anything a small on-device model could write from the same data.

  • Includes every lab value on file — FIB-4, ALT, AST, GGT, lipids, glucose, more
  • Adds fasting compliance, HealthKit exercise, energy, sleep, and body metrics
  • One tap to copy — paste into Claude, ChatGPT, Gemini, Grok, or any LLM
  • Works for any question — lab interpretation, weekly review, or a lifestyle plan
See what’s in the prompt →
Personalized review promptReady to copy
12,847 chars
Includes
Lab values24 results · last 12 mo
Fasting sessions142 · last 90 d
Exercise & energyHealthKit · 90 d
SleepHealthKit · 90 d
Body composition8 metrics
Copied · ready to paste
Paste intoClaude · ChatGPT · Gemini · Grok · Perplexity
Smart fasting timer

Fasting, with the science.

Most fasting apps count down to a number. LivaFast tracks the five metabolic stages actually happening inside you — glycogen depletion, fat burn, ketosis, autophagy, and sustained liver repair — with live transitions based on your individual baseline.

Start a fast on your phone, end it on your Apple Watch, and get a gentle local notification if you haven’t broken your fast by hour 20.

  • Five stages tuned to MASLD-relevant metabolism
  • Apple Watch complication and live activity
  • Never suggests fasts longer than your clinician has cleared
How metabolic stages are modeled →
Autophagy18:24of 20:00 target
Glyco
Fat
Keto
Auto
Liver
0h12h16h18h24h+
Lab interpretation

Skip the math. Let any LLM read your labs.

The app doesn’t calculate FIB-4 or any other risk score on-device anymore. Instead, every lab value you’ve logged — with the date it was drawn — goes into a structured prompt you copy with one tap. The LLM does the math, reads the trend across visits, and writes a review tied to your real numbers.

No more pasting lab results one line at a time. No more screenshots of old PDFs. Paste the prompt into Claude, ChatGPT, Gemini, or any model you trust, and get a plain-English explanation of what’s improving, what’s worsening, and what to bring up at your next appointment.

  • Raw lab values, not precomputed scores — the LLM does the FIB-4 math itself
  • Includes every reading on file, so the LLM sees the full trend, not just today
  • Combines labs with fasting, HealthKit, and body metrics for grounded context
  • Suggests what to discuss with your hepatologist or PCP at the next visit
  • Tap once to copy — works with Claude, ChatGPT, Gemini, Grok, or any LLM
See a sample lab prompt →
Lab interpretation promptRaw values + trend
14,204 chars
Trend included in prompt
FIB-4
2024-081.84
2024-111.51
2025-021.34
2025-051.12
ALT (U/L)
2024-0862
2024-1148
2025-0239
2025-0531
Copied · ready to paste

The LLM calculates FIB-4 itself, reads the trend, and flags topics for your next appointment.

Privacy promise

Your health data never leaves your device.

LivaFast stores everything in CloudKit Private DB — Apple’s end-to-end encrypted store. The developer has zero access. No third-party analytics. No ad SDK. No data broker relationships. Ever.

Upload your labs to our servers—We don’t
Train AI on your data—We don’t
Serve ads, anywhere, ever—We don’t
Sell anything to anyone—We don’t
Use third-party analytics—We don’t
How it works

Three steps. Fifteen minutes. Yours for life.

01

Import your labs.

Scan a lab PDF or type in the values yourself. LivaFast recognizes ALT, AST, GGT, ALP, ferritin, triglycerides, HDL — all the usual suspects.

02

Set your protocol.

Pick a fasting window your clinician has cleared — 14:10, 16:8, or 18:6. LivaFast never suggests protocols outside clinically-reviewed ranges.

03

Copy the prompt, get your review.

When you want a deeper read, tap once to copy a comprehensive prompt — labs, trends, fasting, HealthKit — and paste it into Claude, ChatGPT, Gemini, or any LLM. Export a one-page PDF for your next hepatologist visit.

The Liver Diaries

Mark Chen’s 12-week journey from diagnosis to remission.

A weekly long-form journal — written the way LivaFast is written. Evidence-informed, calm, and honest about the hard parts.

The Liver Diaries
Wk01
Wk02
Wk03
Wk04
Wk05
Wk06
Wk07
Wk08
Wk09
Wk10
Wk11
Wk12
12 Weeks · 12 Chapters
02Act I
Act I — The Wake-Up Call

The Four Floors

It was 2:13 AM, and Mark hadn't slept. He sat at the kitchen table with his laptop glowing in the dark, four levels deep in medical abstracts about liver failure.

Read chapter →
Read Chapter 2: The Four Floors
Read the full 12 chapters →
One app · one price

One app. One price. Own your liver.

No subscriptions. No upsells. No “premium tier.” You buy it once, and every future update is included — for as long as iOS exists.

Download on the App Store
$3999
Once
0
Subs
∞
Updates
Pricing

Pay once. Keep it forever.

LivaFast is a one-time $39.99 purchase on the App Store. Family Sharing works. No renewals. No dark patterns.

LivaFast · iOS 26+
$39.99
One-time purchase.That’s the whole price.
  • Full app, every feature unlocked
  • Apple Watch companion included
  • Personalized review prompt for any LLM
  • All future updates, forever
  • Apple Family Sharing (up to 6)
Download on the App Store
Questions

Before you buy.

No. LivaFast is a wellness tracker for people already under a clinician’s care. It never diagnoses, never prescribes, and always nudges you toward your hepatologist. The app does not compute risk scores itself — the personalized review prompt is informational, not a substitute for a FibroScan or a liver panel.