I have been watching the CHO Used data field. I really like the idea of this field, but it seems to greatly overstate the grams used. I am in the bottom 30% percentile of men over 70 on I’ICU. I rode 3 hrs Friday 8/22, Zone 2, load 169. CHO Used 266g of 1421 calories. I ran the same ride through EatMyRide App and it computed 1426 calories 62% fat and 38% CHO (136g). This calculation matches my expectations for a Z2 ride much more than Intervals.ICU’s calculation. It’s not just this ride, but when riding Z2, I see some interesting results like 8/21, 3h Zone 2, load 182 and CHO Used 312g (x4=1248) and 1244 calories? Maybe revisit the algorithm? I don’t care about the math: would just like to have a good enough estimate of the extra CHO I need to replenish. EatMyRide doesn’t meet my needs, and Intervals.ICU’s approach does if accurate.
Hi OZisKTB,
I do have same experience. There is something strange in ICU algorithm I think.
EatMyRide gives much more credible results, because it uses variables like VO2Max, FTP, HR Zones and FatMax for calculating energy distribution.
I did made very easy 2h36min ride with my wife and my avg. power was 66W. Energy distribution result by EatMyRide was 25% carbs / 75% fat and CHO used was 65g.
Same ride but from ICU calculation gave me CHO used 241g 
- How is this even possible with that easy ride?
Another strange thing was that ICU gave me exactly same CHO used (241g) from exercise which was 1h4min with avg. power 194W / NP 250W.
EatMyRide calculated 76% carbs / 24% fat and CHO used was 147g (138g/h).
I have tried to make a JavaScript with ChatGPT, but with bad results because I am not a code wizard 
I ran basic ride data including GHO consumed during the ride through GROK and it listed all of the assumptions and calculations. Results were very close to EatMyRide.
I agree.
I recently did a 5 hour very easy social ride Intervals put me at 382g CHO.That is 76g/hour!!!
My energy output was only 1454kJ’s which, taking into account my sub-optimal mechanical efficiency gives approx 1745 KCals. Subtracting the “1528 Kcals” from the 382g of CHO. Leaves just 24g of FAT used.
I’m afraid the calculation is so innacurate as to be completely useless . In fact if anyone fuels their rides going off this figure and are doing high volumes it’s not going to be great for their health.
I have a similar issue. Did a 3 hour zone 3 ride, and CHO is 354g, which works out to 1400 calories of carbs. Total ride burned 2000 calories, so basically 3/4ths of calories on a Z2 were carbs? Doesn’t add up.
CHO calc is based on VO2Max from what I read. The issue is likely that value. Not sure where it’s coming from. If intervals is getting VO2Max from Garmin, that’s the issue, Garmin’s VO2Max is hilariously wrong only applicable to a narrow band of the pro athletes they used to train their algorithm. It’s not valid, relevant, or helpful to civilians.
I’ve been computing my carb calories using % of FTP instead. Garmin thinks my FTP is north of 300 (“based on vo2max”, so again a totally invalid number), when actual testing shows it much closer to 210.
You can find the details and the discussion on this topic in the above linked thread.