Fat & Carb consumption

I am not so sure about the fat & carb consumption to be honest. I did a total of 8hrs on Zwift today. All LSD riding. According to Xert i only burned 5grams of carbs over the 8hr period. I am not so sure this can be true even though it was in the fat burning zone. So what happened then to the 30g/hr carbs i consumed during the ride?

They were transformed into and stored as fat :joy:

Honestly, I have no clue how this calculation works and I’ve stopped looking at it…

First off, basal metabolism. Secondly, how dialed in is your signature in regard to LTP?
Thirdly, it’s just another algorithm. :slight_smile: Doesn’t mean it works the same for everyone in all situations.
I use it to more as a warning to slow down on long rides. May as well burn some belly fat while you’re out there.

The bigger question is who the heck rides 8 hrs on Zwift? That would be pure hell to me. :scream:
I’d rather binge on Netflix series. :smiley:

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I did a 7hr ride today, pretty much on my limit for that length (which of course is way below TP). Xert reckons I burned 500g of fat, and 70g of carbs. I wish that were true, but I doubt it. I guess the algorithm works better for high intensity short rides, much like many of the metrics in Xert

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Did an 11 hr ride yesterday and used the fat carb app to guide my effort to avoid running out of energy. It worked, normally I feel the wall at about 3200 calories burned, able reach 6100 calories before I felt the same. Tried to maintain just under LTP and maintain a 1 gm fat to 1 gm carb….usually degraded to 1 gm fat to 2 gm carbs in the hills

Fueled along the way as needed, you only have 500 gm of carbs as glycogen when you start the day. Managing this carb reserve is essential for long rides

Interesting, I suspect your HIE is slightly underestimated, given your Peak Power.

I’d be happy to make a few adjustments on your account - those changes would likely bring your LTP down a bit and shift the breakdown of Carb/Fat for that activity a little more heavily towards carbs. Let me know :slight_smile:

Sure, let’s try a little fine tuning

Not sure it adds value. but additional information to add a little color…

  • Garmin/Strava calories burned = 6566 Vs Xert =5907 for the entire ride
  • Did two breakthrough efforts on hills at 3hr and 8 hrs - it dropped my HIE by -0.2kj, Gain TP +4W. (With out these two efforts I might have avoided feeling “the wall” at 6100 cal)
  • Describe “the wall” as starting to feel exhausted (out of breath), breath rate increases and goes shallow but can still maintain LTP with moderate to significant effort, Symptoms decline with reduced effort.

Hi @ManofSteele, thanks for your help (assuming that was to me?). Why would my HIE be underestimated - does that mean I need to do some more 1min max efforts to calibrate? I reckon my TP is overestimated by about 15W in case that’s also related.

Ha ha guess that was for you. Sorry for stepping on your thread

:grinning: all good. I stepped on someone else’s thread!