Ketone bodies are produced due to an excess of fatty acids being burned (accumulation of acetyl-CoA) so my question is: Why doesn't the body simply regulate how many fats it burns so it doesn't have to produce ketone bodies?

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    $\begingroup$ Under which conditions does the body burn preferrably fats? What makes you think that this process is not optimized (in fact, most biochemical processes are)? $\endgroup$ – Chris Apr 7 '15 at 18:06
  • $\begingroup$ At about 65% VO2 in a trained individual or during fasting. I still don't understand your point, but I assume that it is optimized it just doesn't seem so to me. $\endgroup$ – Paze Apr 7 '15 at 18:51
  • $\begingroup$ When there is not enough fast disposable energy like carbohydrates around. He does this to maintain the support of certain critical tissues, while producing more energy by breaking down fatty acids. If he had glucose (or other sugars) available, this wouldn't happen. Fatty acids cannot be used directly but need to go through beta-oxidation to make the energy available. $\endgroup$ – Chris Apr 7 '15 at 19:01
  • $\begingroup$ I understand that. But I've read that Ketone bodies are supposedly the end-product of beta oxidation, which is not true if I look at the exact process of beta oxidation. Ketone bodies seem to synthesize because an excess of Acetyl-CoA accumulates when fats are burned, so ketone bodies seem to be an unwanted side-effect of too much fat being burned. I'm asking why the body burns so much fat that it gets an excess of acetyl-coa instead of regulating it. $\endgroup$ – Paze Apr 7 '15 at 20:05
  • $\begingroup$ Can you provide a reference for you statement that ketone bodies results from "excess" fatty oxidiation? In my view, ketone bodies are not an unwanted side product, they are deliberately synthesized (mainly by the liver) to support other tissues like the brain when glucose is scarce, as Chris mentioned. Also, I don't think it likely that acetyl-Coa accumulates to high concentrations, since this is limited by the amount of CoA available. $\endgroup$ – Roland May 16 '15 at 8:00

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