How Ketogenesis is Regulated - Human Metabolism
In most biochem textbooks, the topic of ketogenesis (creation of ketone bodies) is accentuated in the context of pathology, such as in uncontrolled Type 1 Diabetes.
In Type 1 Diabetes, ketogenesis occurs in the background of nonexistent endogenous insulin secretion (that is, from within the body). Since insulin is not secreted, glucose cannot enter cells to serve energy metabolism. The body needs fuel and it resorts to breaking down triglycerides from adipocytes into fatty acids and glycerol; fatty acids are degraded to acetyl-CoA.
Acetyl-CoA would undergo into the TCA cycle but it cannot, since TCA cycle intermediates are diverted to gluconeogenesis. Thus, acetyl-CoAs undergo ketogenesis. Ketones can serve as fuel for the brain, muscles, heart and other tissues in the body. However, unregulated ketogenesis increases the pH in the circulation, making it acidic. And this is a condition not to be desired.
What is often left out or just summarily mentioned in textbooks is that people undergoing fasting, those following restricted carbohydrate diets, or in conditions of very low calorie intake or starvation, ketogenesis also takes place. But healthy individuals secrete insulin and acidosis (keto-acidosis) is least likely to take place. However, I would say that blood ketone and urine ketone levels should be monitored - to be on the safe side. For a more technical view, see my video explanation below.