Complex sentence: The next priority of the body is to shift the use of fuel from glucose to fatty acids and ketone bodies-from then on, ketones become more and more important as a source of fuel, while fatty acids and glucose become less important.
Split into simpler sentences: The next priority of the body is to shift the use of fuel from glucose to fatty acids and ketone bodies. From then on, ketones become more and more important as a source of fuel while fatty acids and glucose become less important.