Constitutive Genes- Genes that are always on regardless of environmental conditions Essential for things like repair, proteins synthesis, and metabolism Regulated Genes- Genes expressed only under certain conditions, For example fed vs. starvation state Are we burning Glucose or Fat (Ketones).If we know the difference between Well-Fed and Starvation states, then we can understand what regulated genes are. Starvation state or even ketogenic diets can upregulate Thiophorase (mitochondrial enzyme) to produce ketones Beta-Hydroxybutyrate is an example of a ketone body Ketone Bodies are made in the liver