Why do ketones drop so fast when you eat carbs?
This is something most people wonder but I’ve never seen an answer. I now know.
I was under the assumption, as most people are, that insulin clears ketones somehow and the use of them stops but that is not the case I guess.
Insulin merely inhibits ketogenesis, the creation of new ketones, but it actually increases Ketolysis, the metabolism of ketone bodies, in non-hepatic tissue.
So insulin does stop you from making new ketones but it increases the use of them by tissue like muscle that use them well. Because the supply stops but the demand increases they clear very quickly.
This is why athletes are seeing performance increases from exogenous ketones.
They can’t use fat as efficiently when consuming glucose for sport so they are relying mostly on glucose which of course has limited availability. When ketones are introduced they can be quickly used in muscle during periods of aerobic activity and glucose can be spared for anaerobic activity.