March 7, 2012

Ketosis

The interplay of exercise and ketosis – Part I

Read Time 7 minutes

I embarked on a self-experiment last weekend to see if I could better understand the interplay between the different types of exercise I do and ketone production (beta-hydroxybutyrate, or B-OHB, to be specific).  To be clear, nothing I do with a sample size of one “proves” anything, but sometimes self-experiments can help you formulate hypotheses and, if nothing else, understand how your body works.  Consider the parable of the black sheep.  If you see even a single black sheep in the field, depending on your field of training, you can draw conclusions:

Three scientists were on a train and had just crossed the border into Scotland. A black sheep was grazing on a hillside. The biologist peered out of the window and said, “Look! Scottish sheep are black!” The chemist said, “No, no. Some Scottish sheep are black.” The physicist, with an irritated tone in his voice, said, “My friends, there is at least one field, containing at least one sheep, of which at least one side is black some of the time.”

My point is, even a self-experiment of one can be good for something.

To test the relationship between exercise and ketosis I decided to examine my blood levels of glucose, B-OHB, and lactate immediately before and after three different types of workouts on three successive days.  This interplay is complex and no one knows “everything” about it, including the world’s experts (which I am not pretending to be).  I’m going to try to balance a fine line in this post – I want to be rigorous enough to explore the ideas with substance but not too detailed to put you to sleep.  I hope I am able to balance these forces adequately.

If any of you are not familiar with the work of Jeff Volek and Steve Phinney, but you are interested in the biochemistry of nutritional ketosis, I recommend getting familiar with their work.  The list of people who know more about nutritional ketosis is short.

Let’s take a look at the three parameters I measured in a bit more detail.  To give you a sense of what is “normal” here are some guidelines:

 

Glucose

A normal fasting glucose is generally considered to be between 75 and 100 mg/dL.  My mean over the past year has been about 90, but I need to mention two very important caveats:

  1. On the four occasions I have calibrated my hand-held device with an actual laboratory test, my device seems to run high by about 11 mg/dL, so a measurement of 95 mg/dL on my device is probably closer to 84 mg/dL in reality.
  2. I carry a genetic trait for a disease called beta-thalassemia.  The clinical manifestation of this is that I have much smaller red blood cells than normal (about 65% of normal size).  There is some evidence in the literature that this condition prevents some accurate testing of any assay that can interfere with hemoglobin.  For example, a test measuring glycosylated hemoglobin suggests I have much more glucose in my blood than is actually measured. In fact, the Glycomark test for mean post-meal glucose level suggested I have an average post-meal glucose level of 190 mg/dL which is obviously not true.  In other words, something about my beta-thalassemia seems to interfere with, at the very least, measuring glucose linked to hemoglobin, and possibly measuring glucose in general.

I mention these 2 features to say my glucose levels (unlike B-OHB and lactate which I’ve documented to be very accurate) may be artificially elevated. Here’s the important part, though: the discrepancy seems to be constant, so the increases or decreases seem to be good measurements.

Beta-Hydroxybutyrate (B-OHB)

A normal fasting B-OHB level for a “normal” (i.e., non-ketotic) person is zero.  Within a day of fasting, you might expect this number to reach 0.2 to 0.4 mM, and about 1.0 mM within 48 to 72 hours of complete fasting, though this is highly variable among subjects.

If you’ll recall from my discussion of keto-adaptation, the threshold for nutritional ketosis is about 0.5 mM.  My normal morning fasting level of B-OHB is usually between 1.0 and 2.0 mM with an arithmetic mean of about 1.4 mM.

Both insulin and glucose (probably by causing the secretion of insulin) suppress ketones. This is why, for example, consuming more than about 50 gm of carbohydrates per day and/or more than about 120-150 gm of protein per day makes it difficult to be in nutritional ketosis – too much insulin secretion.

 

Lactate

Lactate (or lactic acid) is a byproduct of anaerobic exercise.  A normal level is considered to be below 2.2 mM.  Basically (I’m oversimplifying a bit), when you exercise in a predominately aerobic capacity, while you do generate lactate your liver is able to match muscle production with clearance via a process called the Cori Cycle (a process in which the liver turns lactate back into glucose).

If you’ve ever done a very intense exercise – like run an all-out mile – and felt like your body is completely seizing up and you are unable to move, you’ve experienced a high lactate.  Technically, the lactate is not causing this.  Lactate gets a pretty bad rap, and it’s actually a good thing as it allows us to generate energy even when we demand it in an environment where sufficient cellular oxygen is absent.  The real “bad guy” is the hydrogen ion that accompanies lactate and interferes with the ability of our muscles to contract and relax properly.  However, we use lactate as a proxy for the hydrogen that is actually causing the pain and difficulty in muscle contraction.

For me (personally, though this is probably true for most people) the highest lactate I generate tends to be in all-out activities lasting about 2 minutes which use all muscles in my body (the more muscles you use, the more lactate you generate).  Hence, the 200 individual medley (IM) race generates the most lactate in my body: It’s 2-plus minutes of maximum exertion sending pain into every muscle in my body (this event requires a swim, in order, of 50 yards each of all-out butterfly, then backstroke, then breaststroke, then freestyle). A runner would probably concur that the 800 meter (half-mile) run is one of the most painful races in that sport.

The highest lactate I have ever measured in myself, following a 200 IM race, was about 16 mM.  I have measured higher levels in several Olympic swimmers, including 20.2 mM in one (as he was vomiting all over the pool deck – for reasons I’ll try to remember to explain in a subsequent post). On my bike, where I’m mostly using my legs, obviously, I think my highest recorded lactate measurement was about 12 or 13 mM following a set of ten 2-minute all-out hill repeats.

I measure my lactate levels using a different hand-held device from the one that measures glucose and B-OHB.

[Another parable, this time about marriage: 2 years ago my father asked me what my wife and I wanted for Christmas.  I said “we” wanted a lactate meter with about 200 test strips (I think it was about $900 for everything).  He looked at me funny, but figured I knew what I was talking about.  When Christmas rolled around and “we” got “our” lactate meter I had to spend a few minutes explaining to my wife why this was a perfect gift for “us” as it allowed “us” to spend lots of time together while she pricked my finger for blood during my workouts.  She didn’t really agree with me.  I clearly don’t understand women very well – I really thought she would find this device “cool.” Which is why this is a blog about health, not marriage.]

 

Results from my experiment

 

Day 1: Saturday (hard swim workout, race pace)

This was a one hour, 45 minute swim with warm-up and cool down.  The “main set” was mostly freestyle and butterfly at all-out race pace for distances of 25, 50, 75, and 100 yard intervals with long rest (1:2 – 2 times more rest than swim time) for the all-out 100 yard swims, and modest rest (2:1 – half the rest time of each swim).  The single most demanding aspect of this workout took place with about 25 minutes remaining and, though I didn’t measure peak lactate, I suspect it was around 12-14 mM, based on the discomfort I experienced. I was surprised that my lactate level was still as high as it was (see below) 25 minutes later, though I suspect I didn’t cool down as gingerly as I should have, to optimize for maximum lactate clearance.

During this workout I consumed nothing and prior to the workout I consumed my usual 40 mL of medium chain triglyceride (MCT) oil.

At 7:29 am, just before beginning the workout, my glucose was 86 mg/dL, B-OHB was 0.7 mM (which is low for my fasting level), and lactate was 1.9 mM.

Immediately post-workout, at 9:14 am, my glucose was 118 mg/dL, B-OHB was 1.0 mM, and lactate was 7.2 mM.

 

Day 2: Sunday (long ride, 80% of race pace)

This was a tempo ride covering 104 miles (167 km) with 5,600 feet of climbing.  Average pace was 17 mph (about 28 km/hr) with lots of headwind.  My average HR over this 6 hour ride was 141 and average power output was between 190 and 200 watts.   There were many sections of the ride, particularly on the climbs, where my HR was sustained in the 160’s for 30 minute stretches and power output was above 275 watts (which, for me, means my muscles generate lactate faster than my liver can clear it).

During this workout I consumed the following:

  1. Two single-serving packets (1 oz) of cream cheese (14 gm fat; 2 gm carb; 2 gm protein)
  2. 50 gm of super starch, by Generation UCAN mixed in my water bottles (50 gm super starch which, technically, is a carb but does not behave like one with respect to insulin secretion and ketone suppression – I will write a dedicated post on super starch in the future, but if you must try it now, use this code to get a discount: “UCANPA”)
  3. 2.5 oz of mixed nuts (25% of each almonds, cashews, walnuts, peanuts – 36 gm fat; 14 gm protein; 15 gm carb)

Total intake during 6 hour ride, therefore, was: 50 gm fat; 16 gm protein; 67 gm carb (of which 50 gm was super-starch), for a total of about 750 calories.

About 90 minutes prior to the ride I consumed 4 eggs fluffed with heavy cream, cream cheese, coffee with heavy cream, and my usual 40 mL of MCT oil.

At 7:56 am, my glucose was 88 mg/dL, B-OHB was 1.3 mM, and lactate was 1.7 mM.

Immediately post-ride, at 2:39 pm, my glucose was 74 mg/dL, B-OHB was 4.4 mM, and lactate was 2.2 mM.

 

Day 3: Monday (dry-land, high intensity training)

On this particular day, it was raining (one of 3 days a year this happens in San Diego), so I did not do the outdoor stuff (including tire flips).

Prior to the workout I consumed nothing other than my usual 40 mL of MCT oil and during the workout I consumed about 4 gm of branched chain amino acids (BCAA) and 10 gm of super starch mixed in my water bottle – so essentially just water.

Immediately prior to the workout, at 6:43 am, my glucose was 77 mg/dL, B-OHB was 3.5 mM*, and lactate was 1.6 mM.

At 7:52 am glucose was 132 mg/dL, B-OHB was 2.2 mM, and lactate was 5.4 mM.

*If you’re wondering why my fasting B-OHB level was so high (recall, I’m usually between 1.0 and 2.0), I suspect it’s at least a partial result of 2 things:

  1. Residual fat breakdown from the previous day’s long ride and caloric deficit, and
  2. On Sunday night I ate (no exaggeration) about half a gallon of my wife’s famous zero sugar, high fat coffee ice cream, which must be the closest thing I’ve ever experienced to heroin in terms of addiction potential.

 

Summary

The figure below summarizes the data from the mini-self-experiment I just described.

 

Exercise summary data

What can we learn about the interaction between glucose, B-OHB, and lactate?

How does super starch impact my ketosis?

Is ketosis helping me or hurting me?

Stay tuned for next week, when I will try to interpret these results…

Photo by James Thomas on Unsplash

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327 Comments

  1. Thank you for your replies. Boy is there ever a lot of bad info on the Internet. One of the Wiki articles talks about the bodies ability to produce glucose. There is so much home spun advice from people who call themselves experts that it is pretty much a toss up as to whether or not people can sort it all out.

    Could you tell me if there is a process within out human system that REQUIRES carbohydrate to function? Would it be POSSIBLE in a clinical setting with adequate monitoring to maintain all bodily functions including brain function with a glucose level of zero?

    I recall reading years ago that a pure protein diet will cause one to lose weight no matter how much protein is consumed but that adding just a bit of carb will allow that protein to be utilized efficiently enough to gain weight. I am not certain why I believed this at the time I read it but I did. I assumed the cause for this was some pathway that absolutely required carb that could not be gotten around in any way at all.

    • Dr. Attia…. I want to thank you for putting me onto the ketogenic diet idea. I have continued to do research on it via the Internet but find that I must do quite a bit of filtering to separate the junk from the good info.

      It simply amazes me that in 53 years of being T1D no one (including medical personnel) has ever mentioned it to me. It has always been about balancing insulin injections and quantities against carb intake and never about eliminating most of the carbs. This diet has already reduced my insulin need substantially and tightened up my BG readings tremendously.

      I’d still like to know the answers to those last couple of questions I posed but completely understand if you feel it inappropriate to answer.

      Your blog has REALLY great info for any T1D and I sure wish that I could somehow get it to the other 100s of T1Ds I have known throughout my life.

      THANK YOU VERY MUCH!

    • Dear Michael,
      I’m a nurse-midwife and although this isn’t my area, I do remember that there are some types of cells (not many), including some types of brain cells, that do require glucose to function. Those particular cells are unable to use any other fuel and must have glucose. It’s not possible for humans to survive with a blood glucose level of zero, BUT we don’t require exogenous carbohydrate from food because we can make our own glucose, enough to supply those cells with what they need.

  2. You left out the social scientist in your anecdote:

    “look, all of the sheep in the world have turned black!!!”

  3. Peter, I’ve read lots of of your posts on how you structure the workouts, watched the video as well. One thing that I wonder about is how you handle stress. The problem seems to be that if you workout hard and often your body will produce cortisol and start producing glucose via gluconeogenesis. Is it less of a problem if you are keto-adapted? Have you tried supplements like e.g. curcuma or cissus which are reported to lower cortisol response? Thanks

  4. Dr Attia,

    Regarding the comment posted by Helga above, if a person has plateau in weight will exercise help? I have been in ketosis according to the ketone sticks (I am planning to get my hands on that handheld device very soon to confirm) for over three months and have exercised for maybe 3 days within this time frame (lol) and haven’t lost any scale weight and my pants are not considerable any looser. Should I be exercising? Will it mobilize my fat storage? Thanks

    • It might for some people, but it could easily do the opposite for others. One thing I’ve experimented with (and will write about at some point) is using intermittent fasting to break through plateaus.

  5. Dear Dr Attia,
    Thank you for all the great information. I am writing with the hopes of getting some comments either from you and/or other readers with experience of being in ketosis. I have been in ketosis for about 6 weeks. I stuck with my normal exercise routine (5 days a week of things like biking, running, lifting, full-court basketball) during induction. I read LATER that keto-induction mixed with exercise could be tough–it was. But after two weeks I felt pretty normal working out. For the most part now when I work out I feel really good. And I love that I can go for a two or even 3 hour bike ride and not have to fuel at all while feeling strong (except at the beginning) the whole ride. I made some mistakes, such as not supplementing with enough sodium, potassium, magnesium, but as I started to take these regularly things like cramping, performance, and overall feeling would get better.

    I initially read Gary Taubes WHY WE GET FAT and started to go low carb (was fairly easy to do). He referred me to you at which point with hopes of losing a bit of fat and taking advantage of all the other benefits of a ketotic diet that you go into, I decided to try being in ketosis. I’ve also read Volek and Phinny, and spent a lot of time on various blogs. I’m really curious about what happens if I bump myself out of ketosis either for a short period or longer period. Will I have to go through a long keto-adaption period again? Will I just drop right back into ketosis as soon as I drop my carbs enough? Part of the reason I ask is that as the weather warms up it feels much harder for me to eat high fat and meat; it just doesn’t quite feel right to be eating burgers with bacon and cheese and passing up fresh cherries and berries. I also start wanting a bit more variety and flexibility with my diet. Another reason is that as much as there is a lot to like about being in ketosis, sometimes I want more flexibility, especially if I’m with a group or doing vacations with my kids. I know ultimately I have to just experiment myself but it’s great to hear form others as well.

    I would be interested to hear other’s experience on being in ketosis, and wonder if there might be a place on your website to post these?

    Thanks again for all your hard work. It’s been fantastic to learn about all of this.

    Jesse

    • It really depends on how “badly” you knock yourself out of ketosis. One meal of too much protein is pretty quick recovery – probably less than 24 hours. Three high-carb meals probably sets you back a few days. Not all carbs have the same impact, so it’s really quite nuanced.

  6. Hi Peter

    Going through your blog and reading EVERY single comment is the best source of information one can find. I really think that down the road (hopefully sooner than later) it is guys like you that will finally turn things around. Keep it up, as hard as it is, I know it keeps you very busy. The way I see it, fighting against these mega industries (farma, USDA,food industries etc…) will have to be hard, and by putting all this information out there for NO profit is making you a hero. Knowledge = Power. Thanks!

    Quick request, can you tell me (us) your TRUE blood glucose levels (if you have more reliable source other than your current devise) from the fasting state, say morning, to an hour after your typical meal and also 2 hours after (no exercise involved). Can’t find much information about “normal” levels for folks in ketosis. I am not taking it as a model, just curious.

    • Thanks for the kind words and encouragement, Aviv. My blood glucose varies quite a bit depending on activity and intake. I’ve measured leaves as low as 50 (after prolonged fasting) and has high as 135 or so after super-intense exercise, where hepatic glucose output is maximal. “Normal” post-prandial might be around 100 and normal fasting after 10 hours might be around 80-90 (for me).

    • Thank you so much. I really don’t want to open my mouth since I got “burned” before, but thing are going the right way, thanks to you.

  7. Hi Peter,

    Before I get to my question, I want to let you know I love your blog and as a fellow engineer, the gritty details are awesome! Anyway, to my question: It is my understanding you continue to actively exercise regularly. Could you address the topic of harmful effects of too much aerobic exercise or “chronic cardio”? I have read several sources with compelling information regarding the harmful effects of too much cardio, etc. As a triathlete, I do my best to utilize interval training and weight training as much as possible, however there are obviously training days dedicated to a more aerobic workout. I want to continue my athletic endeavors, however I do not want to diminish my health along the way.

    Any feedback you are able to provide would be much appreciated.

    Thank you!

    Tom

  8. Hi Peter,
    Have been voraciously reading your blog after finding you on the Web. I’m following the program outlined in “The Art & Science of Low Carbohydrate Performance”, and have been doing about 5% carbs, 15% protein, 80% fat for a little over a week. This is not a radical change as I’ve been very low carb for awhile, but it is my first attempt to get into nutritional ketosis. Feeling crappy, but I knew to expect that. Even with my fat intake up this high my blood ketone levels are usually steady at 0.3 or less, which is starting to get discouraging. I don’t have much energy, but would exercising help move this along? I usually do swimming, walking & P90X, but I’m still quite overweight.
    Thanks for your website, I’ve been desperate to get some answers on this stuff.

  9. I assume your ketone levels on occasion vary from low to high within the optimum range. My question to you – or any readers who’ve made note of it personally – is whether or not you feel “better” with a consistently timed measured ketone level of say 2.0 instead of 1.0? Are there “degrees” of nutritional ketosis in terms of benefits, or are you either in ketosis or not, and by how much doesn’t matter? Thanks,

  10. Hi Dr. Attia,

    I am wondering if you have read any studies on the effects of potassium. I had been taking 90 mg in the morning and 90 mg at night due to painful leg cramps in the middle of the night. I am rethinking how much I am taking since it seems that the supplement is not made in a higher dosage than 90 mg. I am also taking magnesium since I understand they work in conjunction with one another. (For today I made a change and thought I would just take those supplements in the evening.) Thank you in advance for your thoughts.

    Susie

    • You should speak with your doctor about this, as I can’t provide medical advice on this blog. I would need to know more about your health to answer that.

  11. Hey Dr. Attia,

    First, let me apologize for the very long post.

    I have a few random questions, I would understand if you can’t answer them online, but would greatly appreciate it if you could. At the start of the year I went on a Ketogenic diet for about a month (felt amazing, clear mind, everything), but I needed to stop for various reasons. Anyway, recently I decided I wanted to start again, I entered Ketosis a couple of days ago (after realizing I was taking way too much protein, and hence reducing it).

    In this post you mention having more then 120-150g of protein could be too much to stay in Ketosis, with my current diet (67% fat / 5% carbs / 28% protein) I’m getting about 160g of protein per day, would this be a problem? I’d really hate to be on a knife’s edge for staying in Ketosis. (Also if it’s relevant, my fat is a little over 170g and my carbs are 33g – 13g net, 20g fiber). And I’ve had problems increasing my fat without increasing my carbs or protein and still having decent meals.

    Another thing I’m doing is taking a Krill oil capsule in the morning for the extra Omega 3 (was taking 2, but tried lowering it to 1), it seems to interrupt my sleep, I noticed this with Fish oil and swapped to Krill oil hoping it would be different. I generally sleep 8-9 hours a night, but when taking fish/krill oil I wake up 2 – 4 times throughout the night. Do you have any idea why this would be.

    And lastly, I never really been one to get hungry, even when on a high carb diet, now on a low carb diet I’m basically never hungry. You mentioned in one of your posts (sorry, don’t remember which one, I foudn this site yesterday and finished reading them today) that you eat when you get hungry. I understand that hunger is the body’s way of saying it needs more fuel, but should I still try and eat meals and the usual times (I have a full time job so if I don’t prepare meals and bring them with me it’s difficult to properly balance what I eat)?

    And on a side note, thanks for writing this blog, it has answered a lot of my questions and worries about the Ketogenic diet, and will hopefully help lessen the burden of my induction period 😀

    Ah, yea, sorry one more random thing. I get a lot of people asking “why are you on a diet”, and various forms of that question (I’m 5ft 11 and 70kg, and a fit(ish – I do a couple of “boot camp” workout sessions a week and a few hours of football every couple of weeks). Is there any term I can use that will stop people asking questions (like Vegan, Vegetarian, ‘I don’t believe in murdering carbs unnecessarily’)?

    Thanks in advance,

    Morgan

    • Thanks for your questions, Morgan. I’ll try to address many of these when I do my (hopefully soon) series on everything I’ve learned in 18 months of ketosis.

    • Awesome, I look forward to it. I do have another question which would be awesome if you could add it to the list 😀

      I’ve noticed a lot of sodium in a lot of the high-fat foods, is that something I need to worry about? (I’m still within the normal range – about 1750mg), but that’s much more sodium then I was getting on my old healthy version of a high-carb diet.

      I’ll be on the lookout for that new post, and keep up the good work.

      Morgan

  12. Dr Attia, I follow a ketogenic diet but am a practicing judoka, which requires quit a bit of anaerobic work. Would there be a benifit to carb loading the night before a competition? I assume my energy use would be primarily glucose, but would my metabolic flexiblility for burning fat go down remarkedly or would I still have the flexibility and an easier time accessing fat for for energy? Or is there a lag period in which my body can form ketones and avoid quote “hit the wall”? Just curious, I haven’t noticed much fatigue difference on a ketogenic diet, which I mostly have been following for the last 2 years., just hoping for some kind of advantage. Bodybuilders cycle low carb and intermittent high carb, but for different reasons. I was wondering if there is a advantage to this strategy for anerobic athletes. Or should I just stick the ketogenic diet, I think I’ve been on it long enough that my body has gotten good reloading muscles through gluconeogenisis. But is it enough? Has anybody loooked into it? I can’t seem to find the answer ? Sincerely, Darrol Hval

    • I’ve never seen a study that specifically addresses this question, though it’s very easily testable. Studies have looked at variants of this question, but not the exact question (at least to my knowledge). My “gut” for what it’s worth says probably not, as a carb load will take you out of ketosis, thereby confusing your body, which has already adapted to oxidizing fat first, and turning to glycogen only when necessary. You may be interested in experimenting with super starch, though.

  13. A comment and a question.

    Comment: thank you for putting all this information out there, Dr. Attia. My story is a bang on duplicate. I’m a cardio machine, 2 black-belts and well over $100,000 over 12 years in gym fees, personal trainers, nutritionists and eating programs. Oh, and I’m fat. The most fat I ever gained was cycling 2 hours a day for a month and a half. Anyway, I’ve been in ketosis for about a month and a half and I’ve already started to see results, for the first time in over a decade. I’m just SO frustrated that I didn’t know about this when I was 25 years old. Glad I know now.

    Question: I went out of ketosis last week (friends over, non-friendly meals, etc), but immediately went back to eating properly. Typically, I get back into ketosis in a couple days, but not this time. I was still testing completely negative 5 days later. I was also busy with a couple projects and didn’t work out in that time. This morning, I tested negative for ketosis, but went up for a workout, and when I came back, I tested again, and I was in ketosis, finally. Does the workout interact with ketosis in such a way that it would help kick-start it again, or was this just coincidence? Thoughts?

    • Yes, workouts can impact the amount of ketones in your system, in both directions. Below threshold stuff tends to increase B-OHB, while above threshold tends to reduce B-OHB, probably by increase HGO.

    • It is my understanding that ketone strips do not necessarily work long term for every one. If you are drinking enough water, your urine may be too dilute for ketone strips to work and once you have been in ketosis for a while, your body is using the ketones for energy and not spilling as many in the urine. I don’t know this for a fact but I have read it. Maybe Peter can shed some light on this.

      • Urine strips are qualitative, so I don’t use them. Your point is valid, though, because it’s quite likely that what you measure in the urine is not reflective of what’s happening int he blood.

  14. Peter- I found your blog via reading Gary’s. It is very exciting to find a blog loaded with discussions around training and sports performace. My wife gave me a version of “less not thin” as “you should find some races or something to train for”. So I did, but the weight only slowly came off. Then I read Gary’s WGGF and was knocked over. When I saw the biochemistry laid out, I switched my diet that night. I have since dropped 30 lbs and MTB racing is much easier. I have struggled to find the right training and racing foods to eat on the bike so please keep posts about these coming.

    Your post on the VO2Max was fascinating. Have you looked at any of the work by Phil Skiba (he also seems to like calculus)? http://physfarm.com/new/?page_id=563 and his recent study on recovery http://www.ncbi.nlm.nih.gov/pubmed/22382171

  15. Hi Dr. Attia,

    I am relatively new to low carb and have a couple of questions. I do believe in its principles, partly because I went on my first ever Atkins diet at age 8 with my mom, so I feel like I’ve been raised in an Atkins-esque philosophy, even when I didn’t practice it.

    I accidentally removed sugar and processed foods from my diet when I lost my taste buds 3 months ago: no flavor, no point in eating the junk! About a month later I removed all starches, including tubers & legumes (except a rare bite of peanut butter). I eat meats, fish, poultry, cheese, nuts and a ton of fibrous veggies, as well as olive, coconut oils. I eat the odd berry and low carb yogurt (really ,the only processed food I eat). I am trying to keep my proteins down to about 80-120g per day. When I’m careful, I’m at about 50-60g carb and the rest is fats. I am 5’6″, 48 year old female. Maintaining a 90 pound weight loss from years ago. My last hydrostatic bodyfat test has me at about 140 pounds and 24% bodyfat. Of course I’d love to lose those last 5-10 pounds. My workouts vary wildly but I usually work out 5 days a week and I do emphasize weight-training. I enjoy tabata and circuits too and don’t do much in the way of endurance or steady state anything. (If you follow the link to my blog, you can see a few before and after photos etc or my IG feed http://web.stagram.com/n/lasmoothiegirl/ ). OK enough background. Here are my questions:
    1) I was once told that if I ‘hang out’ above my measured Lactate Threshold (144bpm) I will ‘burn muscle’ and have always held to this like gospel- is it true? And is it true whether or not I’m in ketosis?
    2) I felt great when I cut out the starches and sugars – for a couple of months and I think I may have thought I was in ketosis, but now realize that there is no way that I could have been. Recently, I tracked my food to see what my macros really were, and as i said- I was at about 50-60g carbs/day and that was by not-restricting nuts and fibrous veggies to the point where I would have felt dismal. Concurrently I started feeling ‘blah’ like “is this really worth it?” Is it really true that ketosis is binary and that you can’t have benefits in a non-ketogenic, yet still-low carb level?
    3) Have you ever heard of anyone breaking out in a rash when going lower carb/higher fat? It could be very coincidental to some sunscreen I used, but just curious if you’ve ever seen this happen.
    4) Is there a variance in how long it takes to get into ketosis? and is there any value at all (or detriment) to carb-cycling throughout the week? Or does it just mess with your mood and sense of well-being and activity level? I’m pretty sure i could cut back my huge salads every other day or so, but I don’t think I can live my life without them forever. Makes sense?
    5) Did you ever do your self-experiment where you were going to ‘up’ your carbs? Curious how that went?!

    Thank you for listening to my ramblings, and thanks in advance for your response. I really really really really want this to work, but I’m sort of starting to get to a turning point where I have to decide whether to push this envelope further (am I just being impatient?) I’m also a bit bummed because my blog used to feature so many low-fat, high-protein recipes that now I don’t want to freak out my readers with high fat, low carb, mod protein recipes!! 🙂

    • Also, re. #1: Can you please help me understand the mechanism by which the body functions above LT? And since we like the numbering system, I’ll just ask my followup question this way: What does the body use for fuel above the LT in the following conditions?

      1. Non-Ketoadapted person, but fed (carbs, prot, fat mix for example)
      2. Non-Ketoadapted person, but fasted
      3. Keto-adapted person, but fed (fats and a bit of protein)
      4. Keto-adapted person, but fasted

      Are there lab studies on this in the literature? When I did a search for it a while ago, I found nothing, but perhaps I didn’t have access to the best sources?

      By the way- thank you for being so hands-on and replying to most of your comments! It’s really helpful. You are a super busy guy and we know that this takes time and effort on your part.

      • Deb, above LT, the body moves increasingly towards glycogen over fat. The ratio is estimated by the RQ (= VCO2/VO2). Very easy to get this test done on yourself. Look at my post about it.

    • Thanks again for your response. I re-read your post and it makes much more sense to me now. I had forgotten that we have 1000+ calories stored as glycogen. So I’m guessing that the guy who told me that I was ‘burning up my muscle’ above my LT must have misunderstood the energy systems and use of glycogen. In practicality, however, it does make some sense to spend some time below the LT to burn fat rather than glycogen. I’m guessing that this is why HIIT can be beneficial (for other cardiovascular reasons as well, of course) because you still get a great workout with a big calorie burn, yet you can burn more fat (though less overall calories) than had you just hung out above your LT the whole time. Anyway, thanks for the great blog.

      • This is a very important and awfully misunderstood topic. Sometimes I want to start a separate blog devoted to this topic! Of course, that would require a new life, so hopefully I can squeeze stuff into here, now and then.

  16. I am wondering whether slow walking for two hours each morning will help slim down my bulky legs and help me burn fat. I am not worried about calories i am just wondering if it helps burn fat and slim down muscular legs

    • I have zero doubt that 2 hours of slow walking each morning will make you feel much better and, ultimately, nothing matters more than that. Whether it actually helps you lose adipose tissue on your legs is entirely a different matter. I think what you eat (and don’t eat) will have a greater impact on that.

  17. In the hope-it-makes-the-cut-soon category of your articles is what you mentioned in this comment above: “There is almost daily increasing amount of data suggesting that ketones are particularly brain-healthy [and] can play a huge role in preventing and reversing dementia.”

    I do realize that NuSi launches today, that the blog/writing articles will take a quiet ride in the backseat for a while, that you need more time with your family, and more. Still, I respectfully raise my hand. My mother is 89 and experiencing this. Selfishly, I want to do all I can, based on rigorous science to avoid this sad, sorrowful state myself. I turn 60 later this year, one of those “other creatures biologically”. I always knew I was special. 😉

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