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User guide

This document explains, in plain language and without formulas, what the data field shows on screen, what each profile parameter means, and how to configure it. If you want to know how everything is calculated under the hood, see Theoretical basis (the scientific model) or How the app works (how it's implemented).

1. What you see on screen

[ CHO (g)        | 123    ]
[ CHO avg (g/h)  | 45  Z3 ]
[ FAT (g)        | 67     ]
  • CHO (g) — total carbohydrate you've burned since you started the activity.
  • CHO avg (g/h) — the rate at which you're burning carbohydrate right now (a smoothed average, not the raw instantaneous value). It's colored depending on whether this rate is low, medium, or high (see §4).
  • FAT (g) — total fat you've burned since you started the activity.
  • Z1..Z5 (on the right of the middle row) — your current heart rate zone, colored the same way Garmin Connect colors heart rate zones.

2. How to add the field to an activity

  1. On the watch, enter the activity you want (Run, Bike...) without starting it yet.
  2. Press and hold the "Menu" button / swipe to access the activity's options.
  3. Look for "Edit Data Screens" or similar, and pick a screen.
  4. Select the field you want to replace and, under the Connect IQ field category, pick "CHO/FAT Metabolic Pro".

3. Your profile parameters

The app uses 6 values to personalize the calculation. By default they are all in automatic mode (the watch estimates them on its own); you only need to touch them if you know the real value and want more accuracy.

Parameter What it is, in plain terms How it's estimated in automatic mode
Weight Your body weight Read from your Garmin profile
Resting HR Your heart rate at complete rest Read from your Garmin profile
Max HR Your maximum heart rate Taken from the ceiling of zone 5 configured for your current sport (running, cycling...)
LT2 Threshold Your anaerobic threshold (the intensity above which you start accumulating fatigue quickly) Taken from the ceiling of zone 4 configured for your current sport
LT1 Threshold Your aerobic threshold (a bit below the previous one) Calculated as 85% of LT2
VO2max Your maximum aerobic capacity Read from your Garmin profile — the running or cycling estimate, matching your current activity

On a Garmin watch, "current sport" is usually Running; on an Edge bike computer, it's Cycling — the field automatically uses your cycling zones and cycling VO2max estimate in that case, no extra setup needed.

4. How to edit them manually

  1. Open the Connect IQ Store app directly — or, just as well, open the Garmin Connect app and go to your watch → Connect IQ Store (or My Apps).
  2. Find "CHO/FAT Metabolic Pro" and open it.
  3. Tap Settings/Configure and enter any values you know.
  4. Leave any parameter at 0 if you want it to keep being estimated automatically.

Why LT2 matters most — especially for cyclists: of the 6 values, LT2 Threshold has by far the biggest impact on accuracy — LT1 and the point where carb burning starts ramping up are both calculated as a percentage of it, not set independently. If you only enter one value manually, make it this one. 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 Threshold by hand: 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.

5. What the colors mean

CHO avg color (fueling guidance)

Elapsed time Green Orange Red
Under 45 min (always green, glycogen stores are still full) — —
45 min to 2h under 30 g/h 30-60 g/h over 60 g/h
Over 2h under 60 g/h 60-90 g/h over 90 g/h

Red doesn't mean "alarm" — it just means that, according to common sports-nutrition guidelines, you might be falling short on carbohydrate intake for the duration of your effort.

Zone color (Z1..Z5)

Same scheme as Garmin Connect: grey (Z1), blue (Z2), green (Z3), orange (Z4), red (Z5). It's independent of the CHO color — one indicates effort intensity, the other carbohydrate consumption.