Estimating carbohydate needs based on Xert's carb utilization

General
1

I would like to use the carb utilization estimate that Xert gives to plan how many grams of carbohydrate per hour I would need for a similar intensity ride.

I understand this value does not include basal metabolic rate. For example, on a long ride I did recently, I divided up the grams of carbs Xert gave by the number of hours and got 36g. That’s way lower than the standard recommended carb intake of 60-90g’s.

Has anyone else tried this or know how to estimate grams of carbs per hour your BMR requires? Google did not help me :slight_smile:

2

Never mind. I found some calculations, however they are almost always body builder or low-carb/keto diet focused. Plugged in protein/fat numbers which are realistic for me and got 34g/hr over 24 hrs. So, that’s 70g carb per hour on a long bike ride, which hey, fits neatly into the recommendation.

I have a swift playground code to calculate it all if anyone’s interested. (Too lazy to use calculator).

3

This company was trying to do what you describe but it appears their launch may have been a bust.


Not sure how they planned to monetize it.

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4

34g of carb per hour for your BMR seems very high as at 4cals per gram of carb that equals 3264 cals over 24 hours.

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5

You’re right! Thanks. It’s more like 8g per hour. So, wow if this is correct, I only needed 44g/hr.

No wonder I can never eat 60-90g’s/hr. Or maybe I should work harder? :joy:

6

Probably! The amount of Carbs and the ratio of Fat to Carbs varies with intensity. The absolute values are completely unique to an individual and Xert attempts to bespoke them using your particular signature. How accurate is it - I have no idea buts it’s a million times better than “Eat between 60 and 90g grms of carbs an hour” which is the general advice. I’ve attached below 3 images of 5 minute intervals to show you the difference between intensities obviously based on my signature. YMMV though

Screenshot 2020-05-20 at 13.58.23
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Screenshot 2020-05-20 at 13.57.32
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Screenshot 2020-05-20 at 13.55.48
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7

Yes, thank you for illustrating it with your own examples! I have noticed this effect in my own rides/workouts. The ride where I had 36g/hour was a 10 hr, 45 min ride, so it definitely was not high intensity.

My reason for digging into all this is that my favorite events are bikepacking time trials which due to the long bouts of riding (12-15 hrs/day) will be more of a slow-burn. It’s a relief to know how much food I actually need, since the bike is already laden with sleeping and other gear. So, yay data! (Especially data backed by real life experience).

Certainly the profile of whomever the 60-90g recommendations were based on does not match every type of rider or effort.