Popis
Fuel smarter, not by guesswork.
CHO/FAT Metabolic is a Data Field that estimates, second by second, how many grams of carbohydrate and fat your body is burning during exercise — using only your heart rate. No extra sensors, no manual logging.
What you see on screen
- CHO (g) — total carbohydrate burned so far this session.
- CHO avg (g/h) — a smoothed, real-time carbohydrate burn rate, color-coded as a fueling guide: green, orange, or red depending on how your current burn rate compares to standard sports-nutrition intake guidelines for that point in your workout.
- FAT (g) — total fat burned so far this session.
- A small zone indicator (Z1-Z5), colored the same way Garmin Connect colors your heart rate zones, so you can see effort and fueling status at a glance.
Built on established exercise science
The underlying model is not a gimmick — it combines well-known methods from exercise physiology:
- Heart-rate-based VO2 estimation (heart rate reserve method).
- The classic Frayn equations for calculating carbohydrate and fat oxidation from gas-exchange variables.
- Duration-aware carbohydrate fueling bands based on published sports-nutrition guidelines for endurance exercise.
Works out of the box
The app automatically reads your weight, resting heart rate, and heart rate zones from your Garmin profile to personalize the calculation. If you know your own physiological numbers (max heart rate, lactate thresholds, VO2max), you can enter them manually in the app settings for even more accurate results.
A note on accuracy
This app provides an estimate based on established exercise science models, calibrated for endurance athletes. It is a training aid, not a medical or diagnostic device, and should not replace professional medical or nutritional advice.
Tip: for best accuracy, set up your Garmin heart rate zones using the Lactate Threshold method instead of %HRmax — modern Garmin watches estimate your lactate threshold automatically during running/cycling activities (or you can enter it manually). This app estimates your anaerobic threshold from your zone 4 ceiling, so zones based on lactate threshold line up much more closely with the real value.
Tip: fat burning naturally takes a few minutes to ramp up at the start of exercise, so readings in the first 10-20 minutes will lean more toward carbs than later in the session — a short warm-up beforehand can reduce this delay.
Why your anaerobic threshold (LT2) matters most — especially for cyclists
Of all the numbers the app uses, your anaerobic/lactate threshold (LT2) has by far the biggest impact on accuracy. The app's whole carb/fat curve is anchored to it: your aerobic threshold and the point where carb burning starts ramping up are both calculated as a percentage of LT2, not set independently.
This matters even more if you ride with an Edge: Garmin auto-detects lactate threshold for running, but not for cycling — the automatic cycling equivalent is FTP, a power number, not a heart rate. So if you're a cyclist, it's worth setting LT2 manually: use the heart rate from your FTP test (the steady effort, not the wattage itself), or your cycling Lactate Threshold Heart Rate from Garmin Connect's Physiological Metrics if you've set one.
Want the details? Full documentation — User guide plus the underlying science and references — is available at https://irazuzta.github.io/ChoFatMetabolic/
Co je nového
0.3.1: Renamed to CHO/FAT Metabolic Pro — same app, same functionality, no changes to
the calculation. The name change makes this official release easier to tell
apart from earlier test versions.
0.3.0: Added compatibility with Garmin Edge bike computers — a small adaptation of the
original running-focused model to also work for cycling, using your cycling HR
zones and VO2max automatically. No changes to the underlying calculation.
Also added guidance for cyclists on setting your anaerobic threshold (LT2) manually,
since Garmin doesn't auto-detect lactate threshold for cycling the
way it does for running — see the description above and the user guide.
0.2.1: Added support for the new Fenix 9 and Fenix 9 Pro (all sizes).
0.2.0: Added optional manual entry for your LT1 (aerobic threshold) — if you know it from testing, it now improves accuracy the same way max heart rate or LT2 do. Also added a tip on configuring Garmin heart rate zones for best results.
0.1.0: Initial release: real-time CHO/FAT oxidation estimate from heart rate, with color-coded fueling guidance and HR zone indicator.
Snímky obrazovky
Podporovaný jazyk (1)
Kompatibilních zařízení (199)
Approach® S50
Approach® S70 (42mm)
Approach® S70 (47mm)
D2™ Air X15
D2™ Mach 1 Pro
Descent™ G1
Descent™ G1
Descent™ G2
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® Explore 2
Edge® MTB
Enduro™
Enduro™
Enduro™ 2
Enduro™ 3
Enduro™ 4
epix™ (Gen 2)
epix™ (Gen 2)
epix™ Pro (42mm)
epix™ Pro (47mm)
epix™ Pro (51mm)
fēnix® 5 Plus
fēnix® 5 Plus
fēnix® 5S Plus
fēnix® 5S Plus
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
fenix® 9 Pro - 43 mm
fenix® 9 Pro - 47 mm
fenix® 9 Pro - 51 mm
fenix® 9 Pro - Solar 47 mm
fenix® 9 Pro - Solar 51 mm
fēnix® E
ForeAthlete 245
ForeAthlete 245 Music
ForeAthlete 55
ForeAthlete 645 Music
ForeAthlete 745
Forerunner® 165
Forerunner® 165 Music
Forerunner® 170
Forerunner® 170 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 Music
Forerunner® 70
Forerunner® 70
Forerunner® 745
Forerunner® 945
Forerunner® 945
Forerunner® 945 LTE
Forerunner® 955 Dual Power
Forerunner® 965
Forerunner® 970
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
quatix® 6
quatix® 6X
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 Music
vívoactive® 3 Music
vívoactive® 4
vívoactive® 4
vívoactive® 4S
vívoactive® 4S
vívoactive® 5
vívoactive® 6