Going on long bike rides (or otherwise doing any form of endurance workout) can result in "hitting the wall" or "bonking".
The well-known solution is to be mindful of one's carb intake.
But very many folks go on long bike rides (or other endurance workouts) precisely for this reason: to force their bodies to break down fat.
Can someone who is not trying to lose fat (and who really doesn't want to lose weight) take some inspiration from those folks and avoid hitting the wall? Surely they do not practice carb loading (before), gel supplements (during), and glycogen replenishment (after) a ride.
Why is it interesting (and important) to know—even for those who are not trying to lose weight, or who actively do not wish to lose weight? Because it is easy to overdo the starch intake, and so knowing what one should do at a minimum to avoid bonking will also stand as a useful limit. In other words, the cyclist can then "do this" and also take some extra carbs, rather than simply indulge in carbs "to be on the safe side".
It is clear that by erring on this minimum one will be taking the risk of losing fat, but then it appears that even the most athletic still have fat.
Two options are possible:
- Conceivably, the answer may be "it cannot be done," or: taking inspiration from those who succeed in losing fat means that one must also take a risk, and routinely suffer from bonking.
- Earlier this summer, with gyms closed, I bonked on two occasions right after picking up road biking, but this was a fluke. My "glycogen stores" were pathetically low. They may have now improved enough that I need not worry about bonking.
To appreciate just how difficult it is to get this right, read the comments under this answer.
In retrospect, the question I wanted to ask (too late now!) is: What is the minimum carb intake that will be certain to neither: 1- make me bonk, nor 2- "cannibalize" my muscles. When initially asking the question, I expected a simple continuum. Imagine a line with zones A, followed by B, followed by C. The diet in zone A ensures no bonking (that's easy: eat lots of carbs. Drawback: it'll also be too easy to put on weight). The diet in zone C makes the rider lose fat (as many questions here show, that's hard). The surprise is that even identifying just zone B—the objective of this question (no bonk, no targetting of fat) is hard. Oh well!
And if all this is not tough enough to understand, I don't actually mind losing fat, but since my BMI is quite healthy, I suspect my body will end up rebuilding these fat reserves again. The next question in this sequel is then: does one's liver get exhausted from so much work (metabolize fat cells, rebuild fat cells, repeat) ? If you understand enough about all this, feel free to formulate that question as a proper question.