If you go hard enough for long enough, you'll run out of glycogen. If you're not maintaining your blood glucose levels by ingesting carbohydrate, you'll go hypoglycaemic and turn into a wobbly mess of useless limbs.
Finishing a 70.3 on plain water is just about feasible if you're not particularly fast, but a reasonably quick amateur is going to end up bonking in spectacular fashion, let alone an elite athlete.
You can’t really bonk if you’re adapted to and in ketosis. Using only carbs for athletic performance is like having a hybrid car but disconnecting your gas tank.
While training for that, bonk was my second name. Nothing morbid, nothing human can't cope with.
I was not saying anyone can stand up from the bed and go long.
https://www.youtube.com/watch?v=liCRrheKIOI
Finishing a 70.3 on plain water is just about feasible if you're not particularly fast, but a reasonably quick amateur is going to end up bonking in spectacular fashion, let alone an elite athlete.