i am trying to get into ketosis for therapeutic reasons. i am eating about 75% fat, 15% protein, 10% veggie carbs and just started taking some high MCT coconut oil each day. i do not believe i am in ketosis but i must be burning free fatty acids for most of my energy at this point, since i have been VLC for about 3 weeks and recently am keeping my protein intake limited.
what is the difference between FFAs and ketones and how each is metabolized? to be a fat burning beast, are you burning FFAs or ketones or both?
asked bynursling (1178)
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on September 11, 2012
at 08:37 PM
To be "a fat burning beast," yes, you are running on fatty acids and ketones. Ketones are produced as a byproduct of fatty acid metabolism. I'll get a little geeky with the biochem here for a sec: when you burn fatty acids, you produce so much acetyl CoA that it overwhelms the system and gets made into ketones, which are a different form of fuel than fatty acids. Whether or not you can measure your ketone levels via the urine test strips depends on how effective you are at using them, and even how hydrated you are. (If you see very dark purple on the strips, you're probably a little dehydrated.) As time goes on and your body gets very fat/keto-adapted, you'll "spill" fewer ketones out via your urine, sweat, and breath, and will actually burn them more effectively as fuel instead.
Mark Sisson did a fantastic job of explaining all things ketone/fatty acid burning on an episode of Jimmy Moore's Ask the Low Carb Experts podcast. I think the ep was called Ketosis: Devil or Angel. (OR something like that. Very well worth a listen!)
Certain tissues can use fatty acids, and some can't. The brain doesn't do well with fatty acids but loves ketones. (Someone correct me if I'm wrong...I might be. The brain needs fats for structure...loaded with fats...but as a fuel, I think it runs mainly on ketones and glucose.)