You’ll notice around here that I sometimes post papers on the usefulness of ketones yet I rarely talk about ketosis. The reason is that I think ketosis is secondary to the main point. The main point being: run your metabolism off of saturated fatty acids. I do not think that the benefits of a high fat diet stem from being ketotic I think the benefit comes from running your metabolism on fat, even high fat PUFA rats do better than low fat rats when we are speaking of longevity. And I think that I’ve been consistent about that, the saturated fat bit, to the point of ignoring a lot of other things people seem to care about, which I do on purpose because I think it really doesn’t matter.

It’s useful to think of the word “metabolism” and what it really means. I think we can compare this to Cogito ergo sum, “I think, therefore I am” or “I am thinking, therefore I exist”. Do you really think that if you are eating a high carbohydrate diet that “you” exist? What exists in that state is your hyperglycemic self and your hypoglycemic self. Somewhere in the middle you exist, that is where you exist in pure form, that is where your metabolism lies, an efficient one at that. The balancing act between hyper- and hypo- glycemia is amazing. It’s what helps to maintain “form” i.e. you. The things your physiology does to try to maintain OXPHOS and suppress the Crabtree effect thus preventing you from degenerating into giant mass of primitive cells is not appropriately appreciated.

When free fatty acids rise during stress or during sickness or when anything bad happens that is a signal, a good one, that your physiology is trying to maintain form, trying to maintain you, if that doesn’t happen or you block it, degeneration follows, much like when you take statins to try to lower cholesterol. This way of thinking, that because this or that rises during stress or bad times therefore this is bad is completely ignoring the mechanisms that caused the flux in the first place.

It’s like saying the ball dropped because I opened my hand and let it go, without considering gravity and the impact it has if you opened your hand in zero gravity or on another planet. It goes right back to the cause and correlation thinking that a lot of people spend their time pointing out and arguing against.

Judging by comments and walking around the web I think that some people have this idea that if your cells are not running off of glucose then your cells are running off of ketones. The misunderstanding being that if you aren’t feeding your cells glucose that you are eating a lot of fat or glucose deprived and then, that fat (dietary or stored), is being converted into ketones and then being oxidized by your mitochondria. That is a misguided black and white understanding of metabolism.

Your cells prefer to burn saturated fat. End of story. They are happy that way. Every cell in the body that has mitochondria can and does prefer to burn saturated fat. End of story.

If you think “high fat diet” and then automatically think “ketones” you’re missing the point.

Ketones are not a dose dependent fuel source i.e. the more you have floating around the better. I detect a level of lipid hypothesis trains of thoughts when people talk about ketones. For example, some people still believe that low cholestorol is good and that more is bad, without considering what is actually causing the flux. The same is true I think when people are thinking about ketones, the context is not considered.


24 Comments Ketosis

  1. Erik

    Great post edward!
    Do you have any thoughts on why many people including my self didn’t do well on a lower carbohydrate diet in the past.

    Do you think transitioning from a glucose fueled metabolism to a saturated fat fueled one should be done any certain way?

  2. James

    Erik, I’ve been thinking about this a lot. I think something important to consider is that the initial low carb diet could have been high pufa or low nutrients like calcium or low calorie, i.e. stressful. A lot of mainstream recommendations lead to that. Then when one transits from that to something more rich and low-pufa (Peat…), one feels better. But I don’t know many who tried to compare a low-pufa, rich carb diet to a low-pufa, low carb, rich saturated fat diet. I tried and I find that the lactose in milk seems efficient to prevent hypoglycaemia, at least I have it less than on the high carb diet.

  3. Erik

    Thanks for the reply james.
    I think you may be right.
    My initial attempt at low carb was very low calorie and included alot of chicken, duck, and pork fat. Even once I raised the calories, I still had low energy and felt unwell. I think eating tons of sugar like Peat recommends is what helped me regain my matabolisim and energy. However, now I feel that the excess fructose is stressing my liver and I’m having more episodes of low blood sugar than I have ever had. Low carb gave me food sensitivitys that Peat eating seems to have made worse.

    Its been a year since my attempt at low carb and I often wonder how things would have went if I wasn’t restricting calories and eating pufa.

  4. Vince

    Oh, you don’t have to tell me, Edward! Just thought you would get a kick out of that guy.

  5. Montmorency


    I did my own version (from first principles) of low-carb for at least 2-3 years (very low or no explicit PUFA – the only oils I used were coconut and very rarely olive. Ruminant-only meat and organs. No grains. No processed food at home – probably hard to avoid when eating out or a guest, so I probably did have some “hidden” PUFAs, but it was certainly not a high-PUFA diet. (Mystifies me why people, esp. on the RP forum equate “low-carb” with high PUFA)).

    Anyway, I did well on it. This was BP, before discovering Peat. Lost weight. Felt great. Good lipids. I discovered Peat because I was always curious to see if I was missing something. Found him fascinating, although some things were hard to accept (like his views on burning fat for fuel). I modified my diet somewhat in the light of Peat’s views, mainly by adding gelatin, increasing fruit, occasional honey, and more milk. I put on weight … however, Peat says you have to watch your calories, something which had become alien to me on a LC diet, because you just eat to satiety, and that had worked for me. Going back to calorie counting seems to me a retrograde step.

    So, while I was not really convinced about his views on fat-burning, I was prepared to give his glucose-burning ideas a try. On the face of it, it doesn’t seem to have worked out all that well for me (although I still basically feel well, but I don’t like being overweight). I’d like to think I have a genuinely open-mind, and I’m currently undecided about this whole issue, and I will keep reading and keep learning, and carefully keep experimenting on myself. That’s just by way of background to show I’m not anti-sat-fat and not anti-LC at all. But I have a question:

    You state that cells prefer to burn fat, but you don’t cite any evidence. What is the evidence that cells prefer to burn fat?
    (Now, I probably read a lot of evidence on my journey to low-carbs, e.g. reading Gary Taubes’ magnum opus, but also many other places. However, I no longer have that information to hand, and you may be able to provide some fresh evidence).

  6. Matt

    People who talk about ketones don’t usually talk about ketones. They scream about ketones, angrily, at other people whom they differ with semantically in comments sections.

  7. Marco

    Hi Edward,

    do you think there should be a sufficient amount of glucose in the diet to prevent cortisol from rising? Is milk alone sufficient to prevent that, since I can’t see how SFAs would do that.


  8. W.E.

    As someone who has done the Paleo diet well, I can safely say that nothing beats the steady energy of a fat-feuled metabolism. I never understood why so many Peat advocates described Paleo as something completely different (marathon running, eating lean meats, using things like grapeseed oil in their smoothies and olive oil for cooking?!). Maybe I was lucky to stumble on the Primal Blueprint and not some other blog. The LC most people had issues with, when you dig deeper, almost always contains fish and lean muscle meats, not a 60%+ SaFa to carb/ protein ratio.

    When I tried Peat’s (earnestly, for 6 months) I did it becuase it made so much sense and I guess I didn’t trust myself and my cravings for fat. I also wanted to put my beliefs to the test, since Paleo was unravelling for me (becoming commercial).

    It was probably the worst thing that ever happened to me. Chronic insomnia, joint pain, fatigue, depression, acne, weight gain. Feeling like a decrepit old person in my mid twenties! And all my foods come from organic whole foods (juices, fruits, grass-fed gelatin, fresh lean seafood). I hope these symptoms are reversible. I guess maybe I had to lose my health to appreciate what I had. It’s too bad I kept ignoring my ravneous appetite for saturated fats the entire time I was Peating. Now that I’m trying to regain my health I can’t keep a stick of butter last more than a day… ;)

  9. Ben


    I have a story quite similar to yours, with the great success on Paleo followed by a steady decline on a diet of what I gleaned from Peat’s dietary recommendations.

    I’ve been lucky, as have you, to realize that good health gets taken for granted until you experience poor health first hand.

    I’m starting to get my health back, thanks in part to this blog (Edward, I’d be grateful if you could make a list of sites you tend to frequent for information on high fat eating). I can vouch for butter not lasting much more than a day! I’ve been drinking a good bit of kefir, which seems to digest like a charm. Also seems to lower muscle soreness and joint pain. I feel like I’m getting my vigor for life back, which is extremely inspiring!

    Hopefully we can settle into a way of eating that yields as much excitement, flavor as the energy and healing it provides! I sure don’t miss salted sugared oj and milk, but man did I ever enjoy starring to eat warm, hearty, meat/fat centric meals again!

    Best of luck to you,


  10. W.E.

    Thanks Ben.

    Yeah, I’m grateful to Peat because it was a side-step from the Paleo dogma, and I needed it. I also needed to get over my fear of dairy.

    I second Eddie (✌) on Peter’s blog. It’s the most comprehensive blog I’ve ever seen and without much ‘ego’. Once I’m done with Woo’s archive I think I’m gonna have to cut myself off from the never-ending supply of nutritionally oriented science blog. I think I’ve been expecting all this knowledge to eventually trickle into my blood stream and make miracle will happen (), but I think it’s time to n=1 and leave all the other voices behind.

    Good luck to you, Ben!

  11. Edward


    You are correct. Expecting miracles to trickle down is foolish. But n=1 miracles happen all the time. And they happen at the point when you decide to trust yourself instead of trusting what works for others. Trusting what works for others in yourself deny’s the idea that you are individual. At some point I’ll write about mucosa associated lymphoid tissue (MALT) and just how true this idea of individuality is and why n=1 is so important and why n=all is vein and neglects the idea of the adaptive organism.

  12. Matt

    Do you think the same rules apply to mammals other than humans? In other words, do you think carnivores like dogs need a higher ratio of protein to sfa, or would do just as well as humans on high sfa? Do you think humans do need dietary glucose? Following the composition of breast milk relative to cow’s milk, as well as the composition of most diets (some grain as a staple), glucose does seem to be a common feature of the human diet.

  13. robee

    This has been an ongoing question of mine with this whole ketosis thing. Will the body burn fat if it’s not in ketosis, or will it burn carbohydrates and dietary protein/muscle tissue. Also since fats are twice as high in calories people might could overeat if not counting carbs/calories. I feel rather than it being a fatty acid thing it’s a low carbohydrate thing because excessive proteins are turned into fatty acid and transported in the blood in VLDL; along the way it picks up cholesterol in the blood and is now called a LDL.

  14. Edward

    You will burn fat in most states and with different diets although the proportion varies somewhat depending on what you’re eating and depending on the type of fats you are eating. But even on a high carbohydrate diet you are still burning fat. Similarly you’ll produce ketones even while eating a high carbohydrate diet though the proportion varies with how much carbohydrate and depending on circadian rhythm.

  15. robee

    Okay I may have that a little backwards. I meant excess Carbohydrates are turned into fatty acids/triglycerides. So the focus is low carbs. I would not want to have excess carbs in a day if I care about not getting coronary related diseases. So I kind of favor Ketosis, but carbing-up is probably harmless because the glycogen storages in the liver and muscle tissues should be empty in ketosis.

  16. Edward

    I can agree with that. The lines are not so cut and dry as most people would like and I’m o.k. with that. I’m sure we’ll figure it out eventually. I personally think there are more important factors that I’ll write about eventually. Some people do very well with a low carbohydrate diets some do not, for a diet that is supposed to be a sure thing it doesn’t always pan out that way, and then folks say well your doing it wrong, I consider that akin to idiopathic or a paradox, in other words, people can do well but those who don’t we classify as outliers we put them on the fringe and draw lines in the sand, marginalize instinct and intellect, etc. For example, some people eat junk food all the time, are healthy, have hair, smoke and drink, and somehow they have energy and health. Instead the mainstream just says well that is just genetics. Bollucks. There is something else going on, at least that is my personal opinion.

  17. Matt

    Do you think we need carbs, or do you think that healthy people who eat starch are healthy in spite of it?

  18. Craig

    When you say “Your cells prefer to burn saturated fat” do you really mean that metabolism is most efficient when cells burn saturated fat?

    “Your cells don’t prefer anything. Cellular metabolism is a function of chemistry, set in a biological setting (thus the whole notion biochemistry). Chemistry doesn’t prefer anything, it proceeds ‘forward’ based on specific conditions and certain properties…”

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