August 26, 2013


Ketones and Carbohydrates: Can they co-exist?

Can you "carb-load" and stay in ketosis?

Read Time 8 minutes

For reasons I’m still struggling to understand, the idea of “nutritional ketosis” (NK, to be distinguished from starvation ketosis, SK or diabetic ketoacidosis, DKA) is often discussed and debated in much the same way as religion or politics. Perhaps this can be said of all nutrition, which is a shame.  Nevertheless, in my continued defiance of such sensitive topics, I’d like to add another layer of complexity and nuance to this discussion.

The “rule of thumb” for NK is that caloric intake is determined as follows (this excludes a subset of ketogenic diets known as calorie-restricted KD which, as the name suggests, is specifically restricted in calories):

  1. Carbohydrate (total, not “net”): less than 50 gm/day, but ideally closer to 30 gm/day
  2. Protein: up to 1 to 1.5 gm/kg, but ideally below about 120 gm/day
  3. Fat: to satiety

Let me illustrate what this looks like for Joe (left), Jane (middle), and Jeff (right — an example of a calorie restricted KD), three hypothetical people in NK — but each with different caloric requirements.


As a general rule, as caloric requirement increases the proportion of calories derived from carbohydrate and protein decreases (and the contribution of dietary fat increases), even while absolute intake of carbohydrate and protein increases.

Anyone who has bought a blood ketone meter knows how tough it can be to get “into” ketosis by carbohydrate restriction (since everyone asks, I use the Abbott Precision Xtra meter which uses two different strips: one for glucose and one for beta-hydroxybutyrate, or BHB).  Most practitioners consider the minimum threshold of NK to be a fasting serum level of BHB above 0.5 mM.  I’m a bit more stringent in my practice and like to see fasting BHB levels above 1 mM.   To give you a sense of one person’s numbers (mine), over a 6-month stretch in 2013, when I was in NK, my mean (i.e., arithmetic average) morning fasting level was 1.7 mM with a median value of 1.4 mM.  The highest morning level during that period was 5.2 mM.  (The highest morning level I have ever measured in myself is 5.7 mM.)

But, it took me a long time to get it right, especially since at the outset of my foray into NK I was consuming between 4,000 and 4,400 kcal per day.  (My average daily caloric intake for weight stability was about 3,800 kcal per day, which was validated by doubly-labeled water.)  I could still easily “fall out” of NK.  For example, on my daughter’s 5th birthday she insisted I have some of her tikka masala (contains lots of sugar), naan bread, and mango ice cream.  How could I say no to a birthday girl who insisted on going to the nicest Indian restaurant in San Diego?  As to be expected, the next day my BHB was 0.2 mM, and it took me 2 days to get back above 1 mM.

Here’s a little secret I’m about to let everyone in on… I like carbohydrates. I love sushi (though I now mostly eat sashimi).  I love Indian and Thai food, though I prefer to make curry myself to keep sugar out.  I make (and eat) the best hummus this side of the Nile River. I’ve figured out how and when I can eat them to meet the following conditions:

  1. Stay in NK (except on a few occasions like my daughter’s birthday);
  2. Increase my anaerobic performance;
  3. Preserve most (but not all*) of the benefits I enjoyed when I was much more strict about my ketogenic diet.

How, you ask? By learning to calculate my glycogen deficit.

(*) For me, the leanest body composition I achieved as an adult was in strict NK with no attempts to do what I’m about to describe below.  Since I’m not a model and nobody cares if my body fat is 7% or 10%, I’m happy to be a little less lean if it gives me the flexibility to increase performance and live a slightly more sane life.  At least for now.

PLEASE NOTE: I have never suggested, and can’t imagine I ever will suggest, that a KD is “best” or “right” for everyone.  What I describe below may seem extreme, both in the amount of work required and the actual application.  I fully acknowledge that (1) this is a highly analytical approach to eating, and (2) that I’m a “freak” (my wife’s words, not mine). I certainly don’t do this often, unless a lot is on the line (e.g., a big ride), but I like having this technique in my armamentarium.

If you’ve watched my presentation from 2013 at the IHMC, then you’re familiar with RQ.  Through years of metabolic testing I have a pretty good sense of my RQ at any moment in time – when I’m sleeping, when I’m sitting around (most of the time), when I’m riding my bike at 200 watts, when I’m riding my bike at 400 watts, when I’m lifting weights, etc.  This allows me to calculate what proportion of my energy I derive from glycogen and what proportion I derive from fatty acid.  Consider the following example:

If I ride my bike at an average of 185 watts (you’ll need a power meter to infer this) for, say, 2 hours, I know my average RQ is between 0.76 and 0.80.

The approximate formula is %CHO = 3.333*RQ – 2.333, which can easily be derived from the observation that %CHO utilized increases linearly from 0% at RQ 0.7 to 100% at RQ 1.0.

Furthermore, I know my VO2 at 185 watts is 2.9 liters per min, which means (using the Weir formula which I presented previously) my energy requirement was about 14 kcal per minute, or 1,680 kcal over 2 hours.  Hence, of these 1,680 kcal needed to pedal 185 watts for 120 minutes, 336 to 554 kcal came from glycogen.  In other words, I utilized between 84 and 138 gm of glycogen.

(By comparison, several years prior to being in NK, this effort in me would have taken place at a slightly higher VO2 – closer to 3.2 liters per min – and at a much higher RQ – between 0.90 and 0.95 – meaning the exact same work output would have required somewhere between 300 and 400 gm of glycogen!  That’s a real state of metabolic inflexibility.  Basically, I was entirely dependent on carbohydrates for energy.)

Since the first metabolic priority for ingested carbohydrate is glycogen replenishment, I can, in this setting, consume probably somewhere between 60 and 120 gm of carbohydrate following this ride and stay in ketosis.  Why? Because those carbohydrates are prioritized to replenish my glycogen stores AND I am highly insulin sensitive.  Note the *AND* in this last sentence. (The especially astute reader will realize some of this glycogen debt will be replenished by protein and glycerol, the latter of which is liberated by lipolysis – see post on fat flux for a primer).

Clearly I didn’t consume this amount of carbohydrate on my daughter’s birthday, so why was I out of ketosis the next day? Because my glycogen debt was not high.  Of course, I knew this and didn’t really care.  But, if I know my wife wants to go out for sushi one night, and I know she’s going to make me eat a California roll, I can “rig it” such that I show up to dinner with a glycogen debt appropriate enough to enjoy them without significantly interfering with my liver’s BHB production.

Extreme example

At one point, I did two tough bike rides on consecutive days.  Each day we rode 110 miles under challenging conditions.  Over 6,000 feet of climbing each day and very strong winds, which were either headwinds or cross-winds.  On top of this, we rode pretty fast. For the purpose of illustration I recorded everything I did and ate on the second day, which I rode a bit easier than the first day.

The second ride took 6 hours and 5 minutes.  My average normalized power output was 225 watts, and arithmetic average power output was 184 watts.  Based on mechanical work output, this required about 5,000 kcal.  Factoring in the other 18 hours of that day, my total energy expenditure was about 6,800 kcal for the day, obviously not an average day. (A detailed explanation of where the extra 1,800 kcal were expended is beyond what I want to get into now, but it’s basically the energy required to keep me alive – transport ions, contract voluntary and involuntary muscles, etc. — plus move me around, and digest food).

So what did I eat that day?

  1. Breakfast (pre-ride): 5 scrambled eggs, 2 sausage links, 3 pieces of bacon, coffee with cream.
  2. In ride nutrition (I spread this out over 6 hours): 14 oz (not a typo) of salted cashews, 2 Quest bars, 1 peach, 1 apple, 6 bottles of Biosteel High Performance Sports Drink, water. (Since I know someone will ask, I did not consume super starch this day since I was craving cashews as my carbohydrate source and was craving more sodium, given the 90+ degree temperature.)
  3. Late lunch/early dinner (post-ride): 2 oz ham, 3 oz pulled pork, large salad with oil and vinegar dressing, 2 slices of cheddar cheese, 6 mini hamburger patties, 2 tomatoes.

What did this amount to?

  • Fat – 351 gm, or 3,160 kcal of fat
  • Protein – 245 gm, or 980 kcal of protein
  • Carbohydrate – 321 gm, or 1,284 kcal of carbohydrate

(I used package information and Nutritionist Pro software to calculate this.)

Hence, on this day I consumed about 5,400 kcal in total at the following ratio:

  • Fat – 58%
  • Protein – 18%
  • Carbohydrate – 24%

By all conventional wisdom I should not have been in ketosis the next morning, right?

The following morning, my BHB level was 2.2 mM and blood glucose was 5.1 mM.

Teaching point I can’t resist: Following 2 days of significant caloric deficit, about 3,000 kcal in total, I should have in theory lost about a pound (mostly fat, possibly some muscle) which would have been noticed on a scale.  Instead, I gained 8 pounds over those 2 days! Sure it was mostly water retention, both from the glycogen (small) and the fluid accumulating in the interstitial space (“thirds space” fluid losses, large) due to a systemic inflammatory response.  This happens under extreme conditions of exercise.  In fact, the harder I exercise, the more weight I gain, transiently.  I am at my absolute lightest following 2 days of travel (i.e., rest).  So before freaking out at the sight of the scale, keep in mind that most day-to-day weight movement in our bodies is indeed water movement into and out of the plasma and interstitial space, respectively.

What’s my point?

Context matters!  If I ate even one-quarter of that amount of carbohydrate and two-thirds of that protein on a normal day – say, 2.5 hours of riding or 1.5 hour of riding followed by 1 hour of swimming, or a day of travel with no exercise – I would have been out of ketosis for two days or more. (Of course, my appetite on those days would not have allowed me to eat 5,400 kcal without feeling sick, but I won’t get into that until a later post.) But on this day, with these glycogen demands, I was able to maintain the perks of ketosis AND glycolysis simultaneously.

There are days, though, when I overshot my glycogen need and end up with a low BHB and high fasting glucose the following morning. Conversely, there are days I underestimate my glycogen depletion and wake up with very high BHB levels and very low glucose levels (i.e., BHB levels higher than glucose levels, when both measured in mM).

Final thoughts

I felt a bit like I was in unchartered territory because the literature on nutritional ketosis hadn’t really (to my reading) explored this level of extreme activity.  In future posts, I may write about other experiences and self-experiments, including my experience with exogenous (i.e., synthetic) ketones (which I did not use on this ride, but have experimented with on other rides – no, this is not “raspberry ketones” or other such gimmicks).

2017: You can read about one of my earliest experiences with exogenous ketones in this post.

Are carbohydrates necessary to produce 225 watts or more for hours on end? Yes. But, the key is knowing how much you need and when to take them.  A lower RQ at a given level of intensity means less demand on glycogen. In my experience, working with athletes and non-athletes, most tend to make two errors (for lack of a better word):

  1. They over-estimate their carbohydrate requirement, and/or
  2. They forget that no factor influences RQ – and therefore substrate requirement – more than dietary composition during lead up to event (or “life”, which is sort of the ultimate event).

Know your engine, first.  Then fuel it appropriately.

Photo by CloudVisual on Unsplash

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  1. Great Post!

    3 questions.

    1. Does it matter when you consume carbs after some glycogen depletion. I know you did after the workout because of the window of depletion and insulin sensitivity. But if I am glycogen depleted, would I still be able to slowly refill it over 24 hours?

    2. Volek and Phinney advise not taking in carbs after working out. But it seems it primarily has to do with fat loss. If the goal is fat loss, would you also advise not consuming carbs after exercise?

    3. What is your favorite Quest bar? (mine is White Chocolate Raspberry and Apple Pie)

    • 1. Not as much as people think… When glycogen is depleted, assuming you’re reasonably IS, priority #1 for ingested CHO is replenishing glycogen.
      2. I’m not sure I see why. Highly dependent on type of activity. It’s true that ingesting CHO right after workout may increase RQ, thereby reducing fat oxidation, but not by a great amount, especially if glycogen levels are low.
      3. Cookie dough, but I think it’s evil, it tastes so good.

  2. Peter,
    Can I ask your opinion on a question that has been floating around my mind.

    In regards to the race scenarios I have posted above. I keep on thinking, in the first race particularly I started to feel a bit low shortly after I had started to drink a bit of the carb drink I had on the bike, it was a very very weak waxy maise starch solution. I barely had any of it, just sips.
    Obviously then I went on to bonk.

    Could the bonk have been CAUSED by the small amount of carb I ingested? It was on an empty stomach, so could the small amount of carbs caused an insulin response leading to shutting off of endogenous (fat) fuel usage?
    I can’t help thinking that I would have been better if I just stuck with water.

    This has led me to believe that it is better for me to either have no carbs at all, or have lots and lots of them and keep fueling with them regularly.

  3. Hi!

    First let me say how much I appreciate all the self-experiments in pursuit of knowledge and for the passion with which you follow science, wherever it might take you.

    This might depend on bodytype, technique, figtingstyle etc but
    my question to you is, do you think keto-adaption would be beneficial for MMA athletes in general?

    • Great question. I am not sure if keto-adaptation would help, but I do suspect a more measured (vs. unrestricted) approach to CHO would be beneficial. I do work with some MMA trainers and they definitely do best on diet low in “cheap” carbs.

  4. I’m actually typing with a distinct feeling of pleased discomfort, as i tap keys with recently lanced finger tips for the purpose of glucose/ketone testing. 🙂 I have 2 days until the Collingwood Centurion near Toronto, and apparently i was already in a mild NK state (.5) without even knowing what that meant a scant 3 days ago. This is all really good stuff. If i could drink this blog i would be drunk on facts and wondering if that alone would lower my insulin levels (psychosomatic testing has proven to be inconclusive). I do have a question amongst the wordsmithing however. Where the heck do you do RQ testing? Google doesn’t seem to have an answer for this. Hopefully it isn’t strictly reserved for the revered acolytes of medicine amongst us.

    An inquisitive mind that humbly acknowledges how little i understand about my own body.

  5. Hey Peter,

    I’m a professional baseball player and big fan of the blog. Although I’m not sure ketosis is for me, it seems like a no brainer to eliminate sugar and other processed carbs.

    My training (and pitching itself) is pretty much all anaerobic, so I’m wondering if you see a problem with having either carb intake or protein intake, or both, slightly above the threshold of achieving ketosis? Is there a gray area just above ketosis where you don’t reap the rewards of either full ketosis or having adequate glycogen repletion over time?

    I know you said you felt terrible 8 weeks in when your protein intake was too high to reach ketosis, so I’m wondering if limited carbs but higher protein would present a problem.


    • Jack, you’re a fellow Stanford alum, right? Agree that ketosis might not offer a huge advantage to a pitcher (though some, like Volek, would argue ketosis spares amino acids greatly, and therefore offers an advantage to anaerobic and strength athletes, also). A diet low in added sugar and high GI carbs, with compensatory increase in protein and fat (MUFA, SFA over n-6 PUFA, probably?) would probably work well. You may like the Gen UCAN product, super starch.

    • Ha, yes, I am. Lots of good memories there. Okay, thanks for the advice. I’ve got about a 5 month off-season coming up, so plenty of time to experiment with it.

    • Jack,

      A couple of thoughts for your situation.

      One, on a low carb site, one guy commented that any degradation in performance for anaerobic activity went away when he kept his serum ketone level above 2.0.

      Second, I’ve been keto-adapted for 5 years or so. My interpretation of what happens in keto adaptation when you carb up is that your ketone production drops dramatically till you deplete those carbs and then you start making ketones, as needed. This does not require readaptation, in my experience. I view it as keeping the big tanks (fat/ketones) hooked up but with the valve not turned on until needed. I can stay just above the NK level for a few days or a week, and then drop back in by a) being really strict with the diet, b) intense exercise, c) fasting for a day or day and a half or d) some combination of these. The ketones seem to come back when needed. I do try to make sure I’m nice and well into the NK zone periodically so I don’t un-adapt. I really don’t know what the unadaptation time frame is and haven’t experimented to find out. I’m not optimizing ketone output, but still experience many benefits. My RQ must be better as I don’t breath hard at high altitude (I live around 5,600′ but play a lot at 12-13,000′ in the nearby mountains with highly fit friends). I never “have” to eat. I can do hard activity all day without needing to eat (I usually only eat breakfast and dinner anyway). I almost always exercise fasted. My water intake requirement, especially at altitude dropped dramatically. One of my avocations is downhill skiing. I’m 58 and one of my friends is a very fit, 27 year old ski patroller. He tells me I’m the only one of his friends that can keep up with him, even those his age. I attribute this to the keto-adaptation.


  6. Okay so I’m crunching away on all this metabolic biochemistry trying to make sense of keto adaptation at the cellular level and I’m really curious to know if I am even close here. Basically, through macronutrient manipulation one is causing their carbohydrate mediated version of overall energy production through the Kreb’s cycle to stall by exhausting glycolytic based substrates and then re-priming the Kreb’s cycle to flow using substrate that is derived soley from ketone bodies which in turn are derived from FFA either consumed, or released from adipose tissue and then processed by the liver. I’m guessing this is a gradual process moving through some type of progression from whichever organ system, and its associated tissues, would be the quickest to shut down glycolysis to those that would be more resistant and shut it down the slowest. I can’t seem to find any other processes by which ketone bodies can be oxidized for ATP production except aerobically back in the Kreb’s cycle. Some of what I’m reading actually is suggesting that overall ketone bodies MAY be an even better substrate for Acetyl CoA than Pyruvate and generate even fewer ROS byproducts from the ETC.

  7. > … In ride nutrition … 2 Quest bars …

    Prior to your posting that, Amazon could ship an order of these bars immediately. Now they’re back-ordered by nearly a month.

    On the conjecture that this is no coincidence, perhaps you could use your apparently considerable influence to get Quest Nutrition to formulate a line of proper keto bars (the current bars are way too low in fat, and possibly too high in protein).

  8. ……….

    Potential Energy ——— Actual Energy (the end result)

    This is a simple equation that permeates life as we know it – it applies to more or less everything – including diet –

    Forr the sake of simplicity – everything in the diet and diet modalities (such as fasting) -can be given a 100% Potential – the quality of the substrate being the main limiting factor and genetic varibles –

    For this potential to be realized (Actual Energy) – (our product – the end result) -:is shown by the following example’s –

    For those eating high fat daily – the (actual energy)/benifit is somewhere near 0% –

    To fix this – one only needs to limit fat to near zero one day per week and the other six days high fat –

    This one simple change means the difference between no benefit (movement towards death) and maximun benefit(the proloning and quality of life)

    The reverse is also true – those eating a low fat diet should include one day per week that is very high fat – this would fix many of the problems with this sort of diet –

    This same sort of thinking applies to proteins – carbs – fats – and fasting modalities – to sum up – eating the same way seven days per week – month by month – year in year out – causes a movement towards malfunction in some way or another and is not correct –

    The curious thing here is – this is exactly what people do in general

    A simple one day per week adjustment is enough to fix this – as the Lion – he eat’s one day per week and fasts the other six – (I don’t mean this specific modality for people – simply that one day per week needs to be the opposite of the other six –

    Imagine an Earth (this planet) – where it was sunny 365 days per year – no rain – life would quickly disappear and if it rained 365 days per year the result would be similar –

    Regardless of what diet a person follows – there is something wrong with it – substrates and genetic variables and the daily moldality it-self are never perfect – one day per week should be used in a correct manner to fix this –

  9. Hi Peter,
    I just watched the “Advanced Metabolic State” video that you linked at the top of this page. It’s remarkable how much your experience is similar to what I have been doing. I am not nearly as rigorous and data driven as you are. One question that I didn’t see you address, is what adaptations happen when one is chronically low on glycogen, while at the same time forcing extreme bouts of exertion from 15 to 40 minutes long up to 5 times a week, as in a CrossFit WOD. SNS, mostly through adrenalin, seems to do the trick for me, because this is what (from what I have been reading) kick-starts release of free fatty acids from the fat cells. I do get this sensation that my heart is about to jump out of my chest before I even start the WOD. This is how I have been training for years. There are some papers in PubMed about the benefits of low-glycogen training, but they only talk about “train low, compete high”, not “train low, compete low” protocols.

    I would appreciate your thoughts,
    Alexander Dreyzen

  10. Dr. Peter, I found out about you from a recommendation of Tim Ferriss. Honestly, in the past two to three weeks I’ve been researching NK and I have to say that your experiences and videos are the most appropriate from all resources. One thing that I know it’s great and I know you recommend it as well is the research of doctors Volek and Phinney.

    I’m currently reading their Art and Science of Low Carbohydrate Performance as I do a lot of exercising (both cardio and strength training). One question:

    Do 3 fully body workouts in the gym (Tuesday, Thursday, and Saturday – 20 min strength with 8-10 repetitions with 80% of the weight that I can do 1 rep + 20 min of cardio) + 3 kickboxing sessions of 1 and half hours each (on Monday, Wednesday, and Friday) are too much for muscle gain on a low carb diet (with high fat high protein).

    I know you are very busy, but give me the easiest and least time consuming answer that you have on this.
    Thanks Doc, really appreciate everything you do!

  11. Two quick questions, but first I want to say that I LOVE your detailed, evidence based blog. You write truly life-changing posts. I’ve been “paleo” for years, but your and Gary Taubes information takes my understanding to a whole new level.

    1) I searched your site, but I couldn’t find whether you ever posted the FAQ slides from the end of this talk you did for JumpstartMD in Summer 2011 (the end of the video gets cut off).

    JumpstartMD Video –

    2) In The Interplay Between Exercise and Ketosis Parts I and II, you touch on the phenomenon of blood glucose increasing during and post-workout (even when no food is consumed before or during workouts). I believe you mentioned that this increased BG seems to have no effect on your being in / out of ketosis. My question is, if increased BG –> increased insulin secretion –> fat accumlation, does that mean working out promotes fat accumulation? I’m not trying to oversimplify, I’m sure the answer is not straight forward (like most things). What if you’re NOT in ketosis to begin with and working out?


    • 1. No, never posted
      2. Catechol surge, plus increased demand for glycolysis increase HGO and blood glucose rises. This is almost always met with a fall in BHB (and AcAC, I suspect, if we measured it). But there are reasons for this — the rise in glucose (and insulin that follows), and the reason this is happening in the first place, the body is demanding energy at a very fast rate. The latter is driving down BHB and “asking” the liver to breakdown glycogen quickly to release glucose.

  12. Hi Peter,

    I am pretty new to this whole LFHC thing but have become interested in it after reading that Joe Friel has adopted this lifestyle and is functioning well on it.

    I am a category 3 cyclist that trains between 6-12 hours a week on average. I started the new approach to eating about 3 weeks ago cutting my carbs down to about 50g a day and increasing my fat consumption. The first few days were pretty tough as I have lived my whole 43 years on a high carb American diet, but after about a week I was feeling good and the cravings for sugar went away. BUT, I noticed that my cycling went downhill fast. On a ride that normally I would consider an easy or moderate ride/pace I found I fatigued really quickly, had heavy lactate filled legs and took a long time to recover. It was enough that after a few more rides like this, I dropped off the diet all together.

    After a couple of days back on carbs I went for a ride and felt fine. I even included 3 8 minute intervals at 270 watts and never got any lactate and felt fine the next day. But I still wanted to stick with the LCHF diet because I think in the long term it will provide better health and energy day to day, so I have gotten back on it. So I have now been back on it for 4 days. Not really having any cravings for sugar but back out on the bike I am right back where I started. I went for a pretty mellow 2 hour ride 2 days ago staying mostly in the endurance power/HR zone and felt really tired at the end and now 2 days later the legs still feel tired.

    I have searched high and low but can’t really seem to find to much on the web with people experiencing similar problems.

    Wanted to see if you had any thoughts on this and if you experienced anything like this when you switched over to a low carb diet.


    • I understand. I will continue to search. In the meantime should I expect it to pass or do you think I should include more carbs on workout days pre/post ride?

  13. I wish I had found your blog sooner! I have been experimenting with my diet for the last 9 months all with the basic premise that I’m IR and that my weight is a product of not understanding/treating that. I have no medical background or knowledge but have been reading incessantly and had pieced together much of what you explain here. What has brought me serious progress in my weight loss was understanding the IR and focusing on that-as oppososed to weight loss (a distinction that you have repeatedly noted). This simple shift in mindset has had profound consequences for me and my family.

    What made me focus in on the IR was the experiences of my pregnancies (I have 4 children). I read about how IR is normal in pregnancy because it helps facilitate the transfer of nutrients to the fetus. Supposedly, shortly after birth the woman would revert to normal insulin sensitivity. I started wondering if a woman was unaware of this temporary IR state and resumed (or maintained) a “normal American diet” would this set off a snowball effect that essentially prevented her from resuming her pre-pregnancy insulin sensitivity? Anyways, the idea was enough to eventually lead me here 🙂

    Also, I think it would be helpful if some research was devoted to the transition into LC. As you mentioned in another post, even if you know WHAT to do, it doesn’t mean you can make it happen as easily or quickly as you’d like. I think science could have much to contribute here ;-). I have figured out some of my triggers that will set me off course, and I have found some supplements or key foods that support or help me stay on course, but I sure wish there was more solid data in this area.

    Thank you for publishing your experiments and taking the time to explain the science behind all this…so glad someone with the credentials is able to think outside the box!

    • Coco, it warms my heart to know that focusing on IR (vs. weight) has helped you and your family, as I really believe this is the jugular issue. I’m not sure I know the answer to your question, but there are several physiologic states where being IR can help, and some degree of this in pregnancy is likely an example with profound evolutionary pressure. Of course, the post-pregnancy phase, may be another story, as you suggest. To your second point, a lot of us do speculate on exactly what this transition means. For example, is something occurring in the mitochondria? I suspect it is, but we need more science to know for sure.

  14. Dr. Attia, I have a question about Acetone. I have watched many lectures on Biochemistry from online courses trying to get a better understanding of how cell metabolism works to break down substrates into energy and have a loose grasp on Glucose/Fructose/Galactose metabolism and on Fatty Acid metabolism. For the Ketone bodies I understand how acetoacetate and ?-hydroxybutyrate are metabolized through the Acetyl-CoA pathway as well. I had heard multiple times however that when acetoacetate spontaneously degrades to Acetone it becomes strictly a waste product and the body expels it via urine and respiration.

    This morning I stumbled across which states that clinical investigators in 1979 established that Acetone is not just a waste product, approximately 70% of Acetone formed from acetoacetate in the blood is processed by the Liver into Glucose and Protein structures.

    If this study result is accurate then all three of the ketone bodies are very useful for human metabolism, with the Acetone supplying a second source of Glucose along side the Glycerol from the Triglyceride molecules. I would like to believe that this is the case as it would explain how people on strict carb restriction are able to regenerate Glycogen in their muscles much more efficiently than if only the Glycerol and Glucogenic Protein bodies are involved.

    Is Acetone a useful substrate, or just a waste product? If it was proven a useful substrate way back in 1979 why do biochemists still teach that is is a useless waste product?

    • I’m not sure if this is saying acetone is used, per se, for fuel, or just that it rises when other fuels are being produced and used. I’d have to look further. In most folks who are keto-adapted, breath acetone starts to go down, as AcAc use goes up. But I will dig further.

  15. Hi Peter,

    After your body is adjusted to Ketosis (I assume it takes about one full month) and then you binge on carbs for one day, does your body need to readjust to ketosis all over again after that binge day?


    • Depends how long you’ve been adapted. Today, I can slip out with carb- or protein-rich meal, and be right back in the next day. Used to take 2-3 days to rebound. 4 hours of 60-70% VO2 max is a great boost, too!

  16. One of the most exciting new ideas in metabolism that I have seen in a long time, is the idea of adipose tissue plasticity. If in essence, WAT cells can become BAT cells, when they lose much of the triglycerides in them, then, as we lose fat, our basal metabolic rate may actually go up, not down, as the cells switch from storing to burning energy. In the past I was lead to believe that as we lose fat, our metabolism slows down to preserve the stores we have left.

  17. Peter, now that you mention inflammation/SIRT, I was reminded of some stuff I read re LDL/colesterols involvement in immune function, as I am apoe e4 my colesterol is extra high and I read that high LDL is supposed to improve immune function and also that ketogenic diets improve recovery after workout.

    I am mostly in ketosis since dec/2012, with (unfortunately) only 2x long distance a week, but my total colesterol is way higher, than before. In addition to all the common benefits that I experience, I have noticed, even though I still travel weekly by plane, that I havent had a cold pretty much since then, which is strange, since before the ketogenic diet I cought colds frequently.
    In addition, since the beginning of the year, I seem to be more sensitive to mold, especially when contained in sesame products (as they frequently are).
    Might be coincedence, but as all of this has to do with immune function…

    Any idea or possible future blog post about that (colesterols spike on keto diet impact on immune function)?

    • Not sure I know enough about this specific reaction to write about it, but I do have one more post in the long overdue series of cholesterol somewhere in me.

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