In my experience the no-carb bonk feels slightly different than the fatigue from pushing myself to the limit. When I bonk, it hits suddenly, there's no warning at all and suddenly my muscle strength drops to ZERO. That's why I was a bit scared of it happening on the bench press--didn't want to drop the thing on my neck! But when I'm pushing the limit, the drop in strength is less steep and I can make a better assessment of how much I can lift.

Not sure if that helps....

Emily