Description

FatMax % by afasteryou ======================= Train exactly in your personal FatMax zone. FatMax % shows in real time how close you are to your individual maximum fat oxidation rate (FatMax). * 100% = exactly at FatMax * 1%–99% = below or above optimum – fat burn drops as you move away * 0% = at or above Critical Power or Speed – fat metabolism nearly stops ------------------------------------------------------------ HOW IT WORKS 1. Take the afasteryou Powertest (paid, online) or automatically use our Powertest AI via Garmin Sync. Both provide your VO₂max and VLamax – essential for accurate substrate usage calculation. 2. Enter the code shown on your Garmin at: https://afasteryou.com/connect/ 3. It may take up to 10 minutes after activation before the data field updates. Until then, a pairing code will be shown. 4. Add the data field to a Running profile (uses speed) or a Cycling profile (requires power). 5. Start training and aim to stay close to 100% – that’s your personal fat-burning sweet spot. ------------------------------------------------------------ REQUIREMENTS * Cycling – requires a paired power meter * Running – works from speed and altitude; no power sensor needed * The field shows a pairing code until VO2max and VLamax are set * Works indoors as long as power (bike) or speed (run) is recorded ------------------------------------------------------------ DATA SYNC * Your metabolic data (VO2max, VLamax) is synced automatically every 12 hours * If you complete a new Powertest, updates are applied at the next sync ------------------------------------------------------------ ACCURACY Calculations are based on the metabolic model by Alois Mader (2003) and have been validated against laboratory gas exchange data in collaboration with MSH Medical School Hamburg (University of Applied Sciences) ------------------------------------------------------------ WHY USE IT * Train at the exact intensity that maximizes fat metabolism – ideal for endurance, recovery, or weight-loss phases * One clear number, smoothed with a 5-second moving average – easy to read even under effort * Complements your pace, heart rate, or power data for deeper training insight ------------------------------------------------------------ UPCOMING FEATURES * AI-based Powertest support for daily updated metabolic values ------------------------------------------------------------ OTHER PRODUCTS * **Carbs Burned** – tracks cumulative carbohydrate usage based on your personal physiology * **Training AI** – adaptive running and cycling training plans, synced via Garmin Training * **Activity AI** – post-session analytics for Fat, Carbs, VO2max, VLamax, Training Score, CdA, and even muscle and blood lactate simulation ------------------------------------------------------------ SUPPORT Setup guide and FAQ: https://afasteryou.com/fatmax Email: [email protected]

What is new

1.2.0 — Fresh Profile Data • Cached profile data now carries a version stamp. After an app update the field detects the mismatch and fetches your current profile right away instead of waiting for its next scheduled refresh. • It keeps displaying values while that refresh runs, so there is no gap in tracking. The new profile is picked up at your next activity start — numbers never jump mid-ride. • The field also re-checks for updated data during an activity. Until now it stopped asking as soon as it had a profile to work with. 1.1.0 — Refined Running Power Model • Running power on gradients has been re-derived from our own platform data: 219 outdoor runs from 184 athletes, cross-validated against two independent running power meter families and against heart rate. • The resulting gradient response matches the published reference curve of Minetti et al. (2002) — our data and the literature independently arrive at the same model, which is now what the data field uses. • Uphill and downhill sections are now weighted by the measured energy cost of running on a slope, rather than by lifting work alone. Carb burn on rolling and mountainous routes is noticeably more realistic. • Gradient is now averaged over the last 10 s of distance, making it far more robust against barometer noise on the watch. • Flat running is unchanged — identical values to the previous version. • On hilly routes your numbers will differ from 1.0.0. They now match the afasteryou web platform, which runs the same refined model. 1.0.0 — Major Update: Spline Calculation & Smarter Pairing • Fats are now computed via a server-fitted spline curve, so the values match the afasteryou web platform exactly — no more rounding drift. • Smarter pairing flow: 5 min → 10 → 20 → 40 → … re-checks after install. • View switches from "Requesting…" to live fatmax tracking automatically. • Added: D2 Mach 2/Pro, Edge Explore 2, Edge MTB, Forerunner 570, Instinct Crossover AMOLED, Venu 4 (41/45mm), Venu X1. 0.0.8 - Added support for Garmin Edge 550, Edge 850, Forerunner 970, and Fenix 8 devices. 0.0.7 – Activity AI Integration • Added Powertest AI via Garmin Sync – enables real-time carb tracking without a paid Powertest. • VO₂max and VLamax are now estimated automatically from Garmin data. (HF and Power required) • Updated pairing messages and improved background sync performance. • Syncs every 2 min or 10 min (device-dependent); checks for new Powertest (AI) data every 24 h. 0.0.6 – Bugfix for Background Data Visibility • Fixed an issue where the registered flag in background data was not correctly set, which could prevent the pairing code from being hidden as intended. • This bug only affected devices capable of background data handling. All other devices were unaffected. 0.0.5 – Improved messaging and error handling • Data field now displays “Requesting…” until a successful server connection has been made. The pairing code is shown only after the first verified platform request. • Fixed a bug where missing speed values in running activities could cause calculation issues. 0.0.4 – Added internal version tracking 0.0.3 – Improved compatibility with Garmin Edge devices by extracting workout data directly from the info object within compute() 0.0.2 – Fixed bug where readiness check used an incorrect reference 0.0.1 – First release – shows real-time FatMax percentage based on personal metabolic profile. Requires afasteryou Powertest and pairing via afasteryou.com/connect

Screenshots

FatMax by Afasteryou · Screenshot 0 FatMax by Afasteryou · Screenshot 1

Supported language (1)

English

Compatible devices (242)

Approach® S50 Approach® S62 Approach® S62 Approach® S70 (42mm) Approach® S70 (47mm) Captain Marvel Captain Marvel D2™ Air D2™ Air X10 D2™ Air X15 D2™ Delta D2™ Delta PX D2™ Delta PX D2™ Delta S D2™ Mach 1 D2™ Mach 1 Pro D2™ Mach 2 D2™ Mach 2 Pro Darth Vader™ Darth Vader™ Descent™ G1 Descent™ G1 Descent™ G2 Descent™ Mk1 Descent™ Mk1 Descent™ MK2 Descent™ MK2 Descent™ Mk2S Descent™ Mk2S Descent™ MK3 - 43mm Descent™ MK3i - 51mm Edge® 1030 Edge® 1030 Edge® 1030 Plus Edge® 1030 Plus Edge® 1030, Bontrager Edge® 1040 Edge® 1040 Edge® 1050 Edge® 130 Plus Edge® 130 Plus Edge® 530 Edge® 530 Edge® 540 Edge® 550 Edge® 830 Edge® 830 Edge® 840 Edge® 850 Edge® Explore 2 Edge® MTB Enduro™ Enduro™ Enduro™ 2 Enduro™ 3 epix™ (Gen 2) epix™ (Gen 2) epix™ Pro (42mm) epix™ Pro (47mm) epix™ Pro (51mm) fēnix® 5 fēnix® 5 fēnix® 5 Plus fēnix® 5 Plus fēnix® 5S fēnix® 5S fēnix® 5S Plus fēnix® 5S Plus fēnix® 5X fēnix® 5X fēnix® 5X Plus fēnix® 5X Plus fēnix® 6 fēnix® 6 fēnix® 6 Dual Power fēnix® 6 Pro fēnix® 6 Pro fēnix® 6 Pro Dual Power fēnix® 6 Pro Solar fēnix® 6 Solar fēnix® 6S fēnix® 6S fēnix® 6S Dual Power fēnix® 6S Pro fēnix® 6S Pro fēnix® 6S Pro Dual Power fēnix® 6S Pro Solar fēnix® 6S Solar fēnix® 6X Pro fēnix® 6X Pro fēnix® 7 fēnix® 7 fēnix® 7 Pro fēnix® 7 Pro – Solar Edition (No Wi-Fi®) fēnix® 7S fēnix® 7S fēnix® 7S Pro fēnix® 7X fēnix® 7X fēnix® 7X Pro fēnix® 7X Pro No Wi-Fi fēnix® 8 AMOLED (43mm) fēnix® 8 AMOLED (47mm/51mm) fēnix® 8 Pro fēnix® 8 Solar (47mm) fēnix® 8 Solar (51mm) fenix® 9 - 43 mm fenix® 9 – 47 mm fēnix® Chronos fēnix® Chronos fēnix® E First Avenger First Avenger ForeAthlete 245 ForeAthlete 245 Music ForeAthlete 55 ForeAthlete 645 ForeAthlete 645 Music ForeAthlete 745 ForeAthlete 935 Forerunner® 165 Forerunner® 165 Music Forerunner® 245 Forerunner® 245 Forerunner® 245 Music Forerunner® 245 Music Forerunner® 255 Forerunner® 255 Music Forerunner® 255S Forerunner® 255S Music Forerunner® 265 Forerunner® 265S Forerunner® 55 Forerunner® 55 Forerunner® 570 - 42mm Forerunner® 570 - 47mm Forerunner® 645 Forerunner® 645 Music Forerunner® 745 Forerunner® 935 Forerunner® 945 Forerunner® 945 Forerunner® 945 LTE Forerunner® 955 Dual Power Forerunner® 965 Forerunner® 970 GPSMAP® 66i GPSMAP® 66i GPSMAP® 66s / 66st GPSMAP® 66s / 66st GPSMAP® 66sr GPSMAP® 67 GPSMAP® 86i GPSMAP® 86s GPSMAP® 86sc GPSMAP® 86sci Instinct® 2 Instinct® 2 Instinct® 2S Instinct® 2S Instinct® 2X Instinct® 3 – 45 mm, AMOLED Instinct® 3 – 45 mm, Solar Instinct® 3 – 50 mm, AMOLED Instinct® 3 – 50 mm, Solar Instinct® Crossover Instinct® Crossover AMOLED Instinct® E – 40 mm Instinct® E – 45 mm MARQ® (Gen 2) MARQ® Commander (Gen 2) – Carbon Edition MARQ™ Adventurer MARQ™ Adventurer MARQ™ Athlete MARQ™ Athlete MARQ™ Aviator MARQ™ Aviator MARQ™ Aviator (Gen 2) MARQ™ Captain MARQ™ Captain MARQ™ Commander MARQ™ Commander MARQ™ Driver MARQ™ Driver MARQ™ Expedition MARQ™ Expedition MARQ™ Golfer MARQ™ Golfer Mercedes-Benz Venu® Mercedes-Benz Venu® Mercedes-Benz Venu® 2 Mercedes-Benz Venu® 2 Mercedes-Benz Venu® 2S Mercedes-Benz Venu® 2S Montana 700 Montana® 700 Montana® 710 quatix® 6 quatix® 6X Rey™ Rey™ tactix® 7 tactix® 7 – AMOLED Edition tactix® 8 – 47 mm, AMOLED tactix® 8 – 51 mm, Solar Venu® Venu® Venu® 2 Venu® 2 Venu® 2 Plus Venu® 2 Plus Venu® 2S Venu® 2S Venu® 3 Venu® 3S Venu® 4 – 41 mm Venu® 4 – 45 mm Venu® Sq. Venu® Sq. Venu® Sq. Venu® Sq. Venu® Sq. 2 Venu® Sq. 2 Music Venu® Sq. Music Venu® Sq. Music Venu® Sq. Music Venu® Sq. Music Venu® X1 vívoactive® 3 vívoactive® 3 vívoactive® 3 vívoactive® 3 Mercedes-Benz® Collection vívoactive® 3 Mercedes-Benz® Collection vívoactive® 3 Music vívoactive® 3 Music vívoactive® 3 Music vívoactive® 4 vívoactive® 4 vívoactive® 4S vívoactive® 4S vívoactive® 5 vívoactive® 6

Recent metric trend

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Snapshot dates
2026-10-27 → 2026-10-28