Adult web chating
This appears to have been the case in my anecdotal exercise.
The energy necessary to perform the mechanical work did not appear to change much between tests, though the amount of oxygen utilization and fat oxidation did go down measurably.
A very close friend of mine is contemplating a run at the 24 hour world record (cycling).
I think it’s likely we’ll be able to get him to 2 g/min of fat oxidation on the correct diet.
The graph, below, shows the continuous data for VO (measured), and RQ (calculated).
The table below shows the same measurements and calculations as the above table, but under the test conditions.
The latter finding is not surprising since the body was not sitting on an abundant and available source of BHB—there was less need to make BHB “the old fashioned way.” As seen in this exercise, glucose tends to fall quite precipitously following exogenous ketone ingestions.
The upper (blue) line represents oxygen consumption under control conditions, while the lower line (red) represents oxygen consumption following the BHB ingestion.So, for this second effort (the test set) my body did about 5% less mechanical work, while oxidizing about 25% less of my own fat.The majority of this difference, I assume, is from the utilization of the exogenous BHB, and not glucose (again, I will address below what I think is happening with glucose levels).So I decided to find out for myself if ketones could, indeed, offer up the same amount of usable energy with less oxygen consumption. The table below shows the data collected over the first 20 minute effort.The 20 minute effort was continuous, but for the purpose of presenting the data, I’ve shown the segmental values—end of segment for glucose and BHB; segment average for HR, minute ventilation (in m L per min), and RQ; and segment total for minute ventilation (in liters).
I’ve done several tests on myself to see how high I could push fat oxidation rate. This suggests to me that very elite athletes (which I am not) who are highly fat adapted could approach 2 g/min of fat oxidation.