There are three types of ketones. They are:
THE PROCESS OF CREATING KETONES
Acetoacetate is the first ketone created from breaking down fat. This then leads to the formation of Beta-hydroxybutyrate. Acetone is created spontaneously as a side product of acetoacetate via decarboxylation.
WHY OUR BODIES USE KETONES
Humans have always relied on ketones for energy when glucose sources were scarce (i.e. no fruits available during winter). It is a normal state of metabolism. In fact, most babies are born in a state of ketosis.
However, with abundant sources of carbohydrate, people rarely access ketosis and it becomes a dormant metabolic pathway. Our ancestors likely had frequent periods of time when high carbohydrate food wasn’t immediately available.
For this reason, our bodies are amazing at adapting to burning of ketones for fuel.