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

Disclaimer: This blog is for general informational purposes only and does not constitute the practice of medicine, nursing or other professional health care services, including the giving of medical advice, and no doctor/patient relationship is formed. The use of information on this blog or materials linked from this blog is at the user's own risk. The content of this blog is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard, or delay in obtaining, medical advice for any medical condition they may have, and should seek the assistance of their health care professionals for any such conditions.


  1. Hello Peter-

    I have been incredibly successful in achieving some goals through reliance on your information from your blogs. Last week I took 2-3 days and gorged for Christmas. You name it, I ate it. In the past I would occasionally allow myself a sushi roll or something along those lines as a rare treat and be back in mitosis in a matter of hours to half day at most. After my Christmas splurge I was out for almost two days. Even now that I’m back in, it seems very intermittent. The only change has been glutamine, creatine and BCAA supplementation. The brand is prosource so I’m probably imbibing bird feathers from what I have read here, but I’m wondering if you have seen these supplements cause problems with staying in mitosis before. I do about five grams of BCAA during exercise and again after. Glutamine is five grams after, creatine is five grams during and five after.

    My results are probably all the answer I need but I’d like to understand why one or more of these may be causing me problems.

    Thanks in advance,


  2. Hello Peter,

    Is it worth testing blood sugar?

    I have never used a sugar testing strip for the meter I have – just the ketone ones.

    I’m currently using your standard of shooting for > 1 mmol ketones after overnight fast but am wondering if and how you use sugar measurement to help dial in your ketogenic diet.


    • It ads some insights, but I’m not sure it’s necessary. It’s much cheaper than testing BHB, so I always do both together. I like seeing the relationship.

  3. Dr Attia,

    Watched many of your videos and read many a book on Ketosis for athletes. I am 50 years old and still play competitive ice hockey. I I weight train 3x/week. Stats” 69″ and 230lbs (LBM=176). I cannot sustain my favorite sport on 50G CHO /day. I opted to carb backload and it seems to work for hockey, but I cannot drop the 30lbs of bodyfat I would like. Hearing you lost 40lbs is inspiring. I believe I can replicate that feat.
    Just tested Cholesterol’s and Doctor is worried: Total = 251 HDL = 56 Trig = 69 LDL = 189 Non HDL = 195…
    I am trying to figure out if I am in danger here. Trig are low…but the other numbers are worrisome. Your thoughts on the NKD lifestyle and cholesterol would be appreciated.
    Would be nice if we could find Doctors in our area that are similar in conviction to you! Let’s get that going and we can impact millions.

  4. Peter,

    I am a runner in ketosis and I would like to know more about this 50gm ceiling for carbs. I have seen it mentioned in many articles and books, but would like your personal view on whether there is reason to lift this theoretical max after heavy exercise. You have mentioned in another article how you can ‘afford’ an extra does of carbs for your daughters wish of eating Indian by incorporating some high intensity exercise. Can this idea be reversed, such that the body will recover better after the high intensity(or endurance) event by ingesting more carbs? If so, is there are hard and fast rule I can apply to my training, or is everyone different.

    I am only new to ketosis, but my own observation levels is that my ketosis level seems to be influenced heavily by exercise. I am have a higher level of ketones the day after heavy exercise. A day of rest produces a lower result.

    Are their any benefits that you know of to lift the amount of carbs you consume after a heavy dose of exercise. Ideally low glycemic carbs at that. I am not suffering in any way from the reduced carb intake (after my initial 2 weeks), only interested in maximizing my performance.


    • > It is frightening to know how easily rigorously applied
      > science can be overshadowed by headlines/studies like these.

      Here’s a proposed trial that is either designed to produce no
      meaningful results, or had its protocols sabotaged along the way.

      They plan to equalize caloric intake and glycemic load
      between the non-grain/non-dairy subjects and the controls,
      and will only know for sure what they ate at lunch.

      Real trials by NUSI are clearly needed.

    • > It is frightening to know how easily rigorously applied
      > science can be overshadowed by headlines/studies like these.

      And even when what passes for most nutritional science trips over a significant truth, they pick themselves up, shrug it off, and re-focus on the dogma.

      “The Role of Persistent Organic Pollutants in the Worldwide Epidemic of Type 2 Diabetes Mellitus and the Possible Connection to Farmed Atlantic Salmon (Salmo salar)”

      This study accidentally managed to avoid glycemic confounding, by including 692 Greenland Inuit, who are likely on a very low carb, possibly ketogenic diet.

      Quote from paper:
      “More work is required to better understand why such high levels of POPs were not associated with increased risk of T2DM in this population.”

      The Summary makes no mention of the possibility of diet having a potentially substantial effect on health risks, and of course, shows no awareness that T2DM isn’t really a ‘disease’ at all, but just a predictable metabolic response to a full-time glycemic diet.

    • > Very nice insight. Wish more thought of it this way.

      Well, thanks, but it’s shocking to think that I’m so leading edge on that. I’m just an ordinary (non-medical) citizen who has been casually connecting dots since reading Wheat Belly in 2011. What it all leads to seems evident to me.

      For what it’s worth, those two links I posted above were not the result of broad deep digging. They were just two things that popped up lately whilst I was looking for something else.

      This suggests to me, that the issues I raised (1. flawed designs and 2. general obliviousness to blaring klaxons in the data) are depressingly common in current nutrition science. This has to be discouraging to the few enlightened physicians, such as yourself, who actually read nutrition papers.

      Thanks for a very valuable web site.

  5. Dear Dr. Attia,
    Thank you so much for all of the fantastic information you have launched into the ether. You are a gem!
    Right now I am training for an Ironman in July. (I am out of shape and working my butt off). I would really appreciate your advice to a beginner regarding workout vs. race-day fueling. I superstitiously feel that I should simply live my LCHF life during training, but wonder if I should add something on my Ironman day?
    I guess I would like to hear your view about how various carb-based supplements/foods will affect the ability to burn fat during an endurance event. Thank you!!!

    • Please forgive my laziness, Dr. Attia. If I could choose a full-time job of researching and encapsulating your fantastic work I would. I have gathered your advice from a video of perhaps using a slow-release glucose source for activities lasting over about 3 hours, with some salty nuts and BCAA’s. The farther my workouts progress, the greater the confidence I have in what I am doing. I know nuts work great for me and I will look into incorporating the other two items and see how it goes. I know I feel amazing in ketosis and I thank you and other info-maniacs for pioneering this field.

      I test and log my bhob’s twice a day unless I am running an even keel, so I am learning a lot as I go along. I love your approach and admire you personally for all that you are achieving. Thank you!

  6. Hi Peter,
    In case I do a high fat, low carb diet but I just can’t get to ketosis for I don’t know which reason is it a dangerous think? I mean could cholesterol level raise dangerously because my body is not adapted to ketosis? Is it worse then a normal diet, high carb low fat?
    I know HFLC in ketosis is very good but I am nut sure how is it in this area.
    Thank you.

  7. Hi Peter,
    Amazing info available on this site. Thank you
    I have a question or would like your opinion on my eating/nutrition for an eight day mtb stage race I will be taking part in. (The cape epic). I have been on the high fat low carb diet for 9 months now. I have been training for t)his event since November and have done all my training on no carbs only water on the bike. Many training rides over 6 hours, two to three days in a row. We now getting to the high intensity training phase. The question I have is do you think we can ride for 8 days with only a small amount of carbs after the day on the bike as per our normal high fat low carb diet. Or do we need to eat carbs on the bike? Have been fine up to now but not sure how the body will cope after 8 days.

    Your opinion would be really appreciated

  8. Hello Peter
    I am a highly competitive female athlete, considering the low carb and high fat lifestyle for performance and health reasons. I am gluten and dairy free, and also recently grain free. I do not eat red meat however, but do eat all fish, eggs, chicken and turkey. I am very lean and have practically not body fat. I am 5’1 and weight 95lbs and have less than 10% body fat. My naturapath, who works with high level athletes, is a little unsure if this is right for me, I think more because he doesn’t have any experience with the diet and lifestyle. I think he has concerns about a female following this and also I am prone to adrenal fatigue. However, the adrenal fatigue has been due to not just the physical stress I put on my body, but I have a lot of emotional stress at these times in my life when I fell to adrenal fatigue.
    Please let me know what you think

  9. It is absolutely awesome to find such a rigorous report on sport performance on a ketogenic state. I haven’t been doing a lot of aerobics lately and have been trying a not very strict (very much “follow your instincts” when eating) sort of warrior diet. I adored the eating flexibility it gives me and definitively want to stick to any pattern of eating that allows me to have the same freedom. I had been wondering, though, i’ld have to drop this idea when getting back to aerobicks. It’s a joy not only to now it is possible and has serious advantages, but also to have serious literature to instruct me. Keep on!

    Btw, any recommendations on warrior diet style reads? People who are for it seem to get something right, but the litterature on it is a disaster.

  10. Fascinating.

    Here in Japan, perhaps partly due to the Japanese love of rice, we are still encouraged to eat 60% of calories in carbohydrates, and everything is low fat and low carbohydrate. The low carbohydrate diet is partly due to the fact that the Japanese did not traditionally eat much dairy, and many do not have the enzyme to processes lactose. Nutrional advice (e.g. from the Japanese body weight scales manufacturer, Tanita) seems to suggest boiling meats, never using butter, no deep fried, and cutting fats out of the diet completely. While the Japanese are really into healthy living, I can find not one single book in Japanese on low carbohydrate diet. Taubes books do not seem to be translated and there are only two books on the Paleo diet.

    All the same though if you look at “maps of globesity” (Google) it seems that everywhere is fat except East Asia, despite these being “the rice economies,” and that the Chinese eat quite a lot of calories often in the form of rice. The Japanese are fearsomely thin. Is this something to do with rice vs wheat & corn carbohydrates, I wonder.

    When are you going to write a book? What are you book recommendations? I’d like to translate it/them into Japanese.

    • Another thing about the Japanese is that they have a very popular “theory of Japaneseness” (nihonjinron) which has it that Japanese culture is agriculturalists whereas Westerner culture is influenced by that of hunter-gatherers. Absolute duff in my opinion, but the Japanese word for “hunter (gatherer)” is closely associated with Westerner, Western food, and ill-health (since after all, as the Japanese know, Westerners are so much fatter).

      So it is no wonder that the paleo diet book did not sell well since it seems, from Japanese eyes, to be selling Western (hunter-gatherer) (ill-) health advice. It says on the front cover “In hunter-gatherer societies no one was fat.” I can imagine Japanese reading that and rolling their eyes.

      The truth may be the reverse, that in fact that Japanese used to eat little rice till recently (it was used to pay taxes, but the common people rarely ate it) and did in fact enjoy a lot of fish and meats. They are the hunter (fisher) gatherers and we are the corn-starch stuffed agriculturalists.

  11. Peter,

    Been following your blog for a few months now and 10 days ago finally took the leap into Keto. Two days back I just received my glucose/ketone meter and have done some readings (a lot less painful than I was expecting, btw!)

    Anyway, what’s interesting me is both days (yesterday and today: testing both morning and night) all Ketone readings thus far are between 1.2 mmol/L & 1.6 mmol/L.

    From reading your blog, these numbers seem abnormally high for someone doing Keto for such a short period of time (10 days) — with that kind of reading, am I technically in NK already, so soon? You seem to suggest it typically takes 4-6 weeks to achieve NK, yet my blood results after 10 days say otherwise. Just curious on your take on that!

    Thanks for the killer content,

  12. Hit this yesterday after a 6 hour tramp with zero carbohydrates and large amounts of MCT.

    What are your views on using MCT as a ‘catalyst’ into NK, I have noticed some days in the morning I will be around 1.5 but I can bump it up to high 2’s just from having two lots of 30grams of MCT oil.

    How accurate are the ketone strips on the precision? I notice that the glucose can have quite a large margin of error, and I usually double test. I’ve double tested beta hydroxy once, but would obviously prefer not due to the cost of the strips.


    • MCT is, as you say, a catalyst for some. Most folks can only tolerate so much of it, typically between 15 and 45 mL per day. Yes, glucose variability is about 10% on those strips. Seems a bit better on ketones.

  13. I have a couple of questions. I have been utilizing LCHF for about 4 weeks now. My carb intake is about 20g a day. My protein is around 130g (lean body weight is 150). And my fats represent between 75-80% of my intake. I’m shredding weight like I never had before. And it’s been very easy, because I’m satiated all the time.

    However, as a triathlete, I’m struggling. My long easy runs are brutal. Prior to switching to this diet, I would hold my long easy runs at a 9 minute pace with a HR of 150. I could do this pace all day and usually run my 20 milers feeling good afterwards. Now I’m struggling to keep a 10 minute pace and my HR is about 153. And when I say struggle, I feel like I’m running on legs filled with lead. Additionally, my swims (I’m not a very good swimmer) have also been affected and after a 100m warm up, I can already feel my arms and legs burning.

    I read about your fueling over the course of your 6 hour ride. It occurred to me that I’m pretty depleted. Unfortunately I have no idea how to replenish my glucose deficiency without knocking my self out of ketosis. I have a 15k trail run tomorrow and have a feeling I’m going to be struggling with it. I thought about experimenting and increasing my carb intake tonight and in the morning, but with what? How do I eat enough carbs for it to be useful tomorrow? And when do I do it? And will that effect ketosis? Will my body quit using fat as fuel on the race if fuel up with too many carbs?

    Thanks for all you do and insight you could give,

    • No quick answer to this, but there are 5 or 6 posts throughout the blog that address this, including the one you’re commenting. Did you see how much CHO I ingested while remaining in ketosis, given my expenditure?

  14. Hey Doc,

    For those of us who use the low-tech way to monitor ketosis (urine strips), what do you think about the idea that seeing red-purple on the strips after several weeks in ketosis isn’t really a good thing. I always thought it was,
    but then I read an article by Steve Fowkes where he talks about being in fat burning mode vs being ‘efficient’ in fat burning mode. He says that acetone breath and dark colored urine strips indicate not being efficient in fat burning mode and that excess ketones in the blood results in excessive cross linking. My strips are consistently dark red-purple when I test.

  15. Peter,

    I have greatly benefitted from all the information you have shared through your posts, videos, and podcast interviews. Love the content, love the delivery even more.

    Like a lot of others, I too find myself eagerly awaiting the next Eating Academy article. Especially the Insulin/Leptin one, which according to the Coming Soon page is 9 articles away.

    NK (confirmed through blood ketone measurement) took me (31 yr. old resistance-training male) from 25% body fat to 15%, after which the fat loss stalled. Signs pointed to what the internet said was a case of low(ered) leptin levels. The internet also said I needed a weekly “carb refeed”. I quickly dismissed that theory as bro-science until I found Mark Sisson’s articles where he too suggested refeeds as a tool for non-metabolically deranged, stalled individuals seeking to get to ab-territory (10% bf).

    From reading your other posts, I know that the short answer to whether carb-refeeds are necessary is that they aren’t, and that they pose more downside than upside by not allowing the body to fully adapt metabolically. The long answer… I suspect I’ll find in your Insulin/Leptin post.

    In 10 years of pursuing strength, fitness, and health, I have never been this excited. Thank you, Peter!

    • Ahh… the sad internet misunderstandings of leptin. Leptin levels are proportional to fat mass. Less fat mass = less leptin. Low leptin may well drive appetite, but there is no evidence that high leptin suppresses it in people without genetic defect (very rare). That’s the post!

    • Thanks for clarifying the appetite part, Peter.

      How about metabolism and energy expenditure, do those go down as leptin levels drop? In which case if one were consuming not more but the same amount of food but now spending less energy, fat loss would then probably slow down or stall?

      These are the Mark’s Daily Apple posts which got me wondering,

      • Well, this is a much more complicated question with conflicting data. Certainly some of the finest experimentalists have shown, in some settings, that EE does go down at weight goes down. And while losing weight often implies reducing circulating leptin (see previous response), I don’t think anyone thinks the reduction in leptin is the cause of reduced EE. Other hormones, most likely thyroid, play a greater role if and when this occurs.

    • If it is indeed thyroid playing a role in reducing energy expenditure as weight goes down, would you be of the opinion that increasing carb. intake would still not be the way to remedy the situation?

      Curious what your experience and the data you’ve seen suggest.

      Thanks again, very much!

  16. Firstly – thank you for the work you’re doing and for making your findings accessible.

    I am a type 1 diabetic in the process of converting to the ketogenic diet. I’m watching salt etc and having no problems other than a sudden and consistent rise in blood pressure during the day. (Fine overnight.)

    Is this to be expected during the change over and will therefore subside?

    My blood sugars are already improving dramatically, (normal most of the time) but I have retinopathy so high BP is not good. GP blames the diet – but then he’s very anti it.

    I really don’t want to have to give up!


    • Giselle, you find value in reading the book by Dr. Richard Bernstein, who is himself a T1D. Might be worth sharing with your doctor, too.

  17. We really need a post from Peter on leptin! I have personally come to the understanding so far that in lot of cases it is calorie restrction that triggers thyroid like symptoms/issues and weight stalls but mostly it is carb restriction that takes the blame. In carb refeeds is it more calories or carbs that apparently kick start the metabolism? Similarly CarbNite solution recommends under 30 grams of carbs with one night of carb binging, here, is it going under 30 grams of carbs causing the fat loss or carb night.? I would argue it is low carb. John Kiefer as he describes in CarbNite Solution, was on ultra low carb diet for 5 weeks and then he binged on donuts one night. Couple of days after that he noticed fat loss, this according to him was the birth of CarbNite Solution. We have to ask here: is it the continuation of ultra low carb that caused fat loss or donuts? In the case of leptin and satiety issue we have to ask why does it not work in obese as they have plenty of food available, they still have to eat a lot and high leptin does not trigger/cause fat loss there. As explained by Gary Leptin is a down stream effect of insulin. We also have to ask how metabolically safe carb refeed is long term as this way one is really beating the insulin with the hammer.

    • Thanks for sharing your thoughts, Norm.

      As much as I’d like to think I was eating adequate fat while being in Nutritional Ketosis, I think I might have succumbed a bit to the fear of fat. In addition, the inherent satiety of a keto diet probably put me into a calorie restricted state leading to low thyroid-like symptoms and slow/stalled fat loss.

      The hedonistic pleasures dangled by the refeed camp only make the bro-science distractions worse.

      Moral of the story: EAT MORE FAT.

  18. I think the answer to this question is on your website but I just have not been able to find it yet. In the absence of insulin because all you ate for a meal is fat, what happens to the fat that you digest?

  19. Thank you – yes I am very familiar with Bernstein – but no mention of BP.

    Might have cracked it though – could be the cut in caffeine. Reduced my tea intake because of restricting milk. A cup of black tea seems to bring it down. Odd but seems to work – thought I’d let you know in case others find something similar.

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