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Bodyrecomposition Mailbag 2

Since I can’t think of any actual topic this week and think I can answer these questions in a fairly brief manner, I’m just going to clear out some of my questions.  Topics will include women and DEXA, oddities about pregnancy metabolism, endurance nutrition and a bit about health habits when you have bipolar.

DEXA and Bodyfat Measurement

Question: Hi Lyle, I recently did a DEXA scan to get an estimate of my body fat % – I’m female, 28 years old, weight train regularly. My DEXA scan results: 5’3, weighing 59kg and an ‘average’ of 20% body fat. I say ‘average’ as the scan showed that the body fat % in my upper body (arms, torso) was 14% while my lower body (hips, thighs) was 27%. Is it fair for me to take the average of these and consider myself to be 20% body fat?

Answer: The above type of question is becoming more and more frequent as more people are using DEXA scans to get an estimate of bodyfat percentage (BF%).   Because of the way DEXA works, it will churn out different BF% for the upper and lower body and this can be confusing.  First and foremost, the above is a completely normal female body fat patterning as women generally carry more body fat in the lower body than upper body (a male would typically have the opposite pattern).

I say generally as there can be exceptions where women have either a very even body fat pattern or more of a male-like upper body fat patterning; the latter typically occurs in situations were testosterone is above normal.  So far as the main question, should the values be averaged to get a usable BF%? The answer is yes.  In any of my books and most discussions of applications of BF%, it’s whole-body BF% that is relevant, not the individual distributions.

BMR in Pregnancy

Question: Given your knowledge of human metabolism, I was wondering if you could make sense of why there is a relationship between body fat and metabolic rate in pregnant women.

Answer: The paper in question deals with the issue of resting metabolic rate (RMR) and it’s determinants.  Normally, the largest determinant of RMR is lean body mass (LBM).  Here I’m talking about all LBM, not just muscle.  Organs, brain, etc. actually burn far more calories per day than muscle and LBM predicts a majority (off the top of my head: 75% or so) of RMR.  But this study found that in pregnant women, it was the amount of body fat that predicted RMR, concluding that:

It is proposed that pregnancy represents a unique condition during which BMR is regulated by maternal adipose reserves. An augmented BMR in overweight pregnant women may be protective, given that excessive weight gain may be detrimental to neonatal and maternal health.

First and foremost, realize that in the age of leptin, we know that a great deal of metabolism is regulated by body fat stores.  Quite in fact, as body fat drops, it is the loss of body fat that contributes significantly to the drop in resting energy expenditure.  This isn’t due to the actual calorie burn of fat cells (which is quite low) but rather due to what’s happening hormonally (primarily the drop in leptin).

In any case, first let me state that pregnancy is neither my area of interest nor expertise.  I touch only on it like twice in the The Women’s Book Vol 1 and can only comment so much here.  But a lot changes in pregnancy and the basic fact is that at least part of why women store more fat than men (and specifically in the lower body) is due to the crucial importance of body fat during pregnancy and breastfeeding.

Fat is used preferentially towards the end of pregnancy for fuel and fuels breastfeeding; quite in fact the normally difficult mobilization of lower body fat reverses itself with that fat becoming easier to mobilize (years ago I played with the idea of trying to mimick the hormonal situation of breastfeeding to cause this but the project went nowhere).

But this means that it makes a certain logical sense that women’s metabolisms would be controlled by body fat in this one situation; this would be to ensure that sufficient calories are available for the baby instead of being burned off for other reasons.  I’m not entirely sure what their conclusion is getting at but overall it’s just saying that there is a change in metabolism during pregnancy where body fat becomes the regulator of RMR.

Optimal Endurance Nutrition

Good Afternoon, I have been reading your site for a while and have put lots of it to good uses but one thing I cant find and its my area of struggle. Fueling my post work afternoon (3pm) workouts. I am a competitive cyclist and often 2 week day hard workouts as soon as i get home from work. I will eat a small lunch then 1-1.5 hrs after it I will eat what more resembles a lunch about 500-600 cals which puts me 2 hrs out from my intense workout. But I often need to take on addition cals during ride to finish it with success otherwise it gets ugly. Any suggestions? thanks!


An enormous amount of research has looked at the issue of endurance nutrition both in terms of fluid and nutrient intake (this is all discussed ad nauseum in The Protein Book).  In basic summary, a fluid intake of roughly 32 oz per hour (a large water bottle is typically 28 oz or so) with 30-60 grams of carbohydrate (from some type of glucose solution generally) and *maybe* 8-10 grams of a rapidly digestible protein (think whey) is considered optimal.  Cool fluids seem to be absorbed most quickly and the tiny bit of sodium/potassium is, contrary to belief, mainly there for taste reasons.

A little bit more carbohydrate (up to like 70 grams per hour) can be used if a mixture of carbs (i.e. glucose and some fructose) is used and the whey protein *may* help to limit muscle damage and *might* help with performance (this is debatable).

For easier or shorter rides, 30 grams of carbs per hour and less total fluid is usually fine and for harder workouts, 60 grams per hour in the full fluid would be appropriate.  It’s important to use enough fluid if you use the maximum carbs since extremely concentrated solutions (above around 7% or thereabouts) aren’t absorbed as well.

Note: women can get by with about half the amounts of both fluid and carbohydrate that would be typical for males for various reasons).

Drinking about 1/4 of the bottle (~8 fluid) every 15 minutes or so will provide sufficient fluid and nutrients to fuel the ride.  If you’re going into the ride particularly underfed, you can start the ride with a drink, or wait until you’re in your warmups.  Some people can get a drop in blood sugar (it’s more rare than you’d think) but exercise blunts the insulin response to carbs.

Diet and Exercise for Bipolar

Hi Lyle I am also Bipolar II (discovered and diagnosed by chance about four years ago) and find a lot of what you wrote on the subject this past year very familiar. I’m wondering, however, if you have a specific diet and exercise routine you would suggest for bipolar people? I’d like to add that I’m also ADHD so I prefer to keep carbs as low as possible as it tends to clear my mind, I’m just not sure if that is optimum given my overall mental condition.


Ok, this is a question I thought long and hard about answering although I’ve addressed what I personally do to some degree in my various updates.   I’m going to address it in a sort of roundabout fashion by only describing what I personally do or was recommended by my Nurse Practitioner.

I’m taking this approach since this is an issue of mental illness, I’m not a qualified professional on the topic and, to date, I’ve only looked into it very superficially and the potential ramifications of anything that goes wrong can be enormous. So, just as I would at a DBSA support meeting, I will talk only from my own experience with no recommendations being made or implied.

When I was first diagnosed, the basic gist of what my NP and psychiatrist recommended was:

  1. Ensuring a solid sleep schedule (too little sleep can induce hypomania).  I go to sleep every night by 11pm and wake up at 8:30 to feed and potty my dogs and the number of times I haven’t done this in the last year I can count on less than one hand.
  2. Regular exercise.  They recommended 7 times per week and when I asked why, they said that if they recommend 7, people might do 5 but if they recommend 5 people will do 3.  This is true.  While they skirted on details, regular exercise helps to, as my NP put it “Eliminate crud in the brain.” That’s as technical as I’ve gotten on the topic.  I personally am currently doing 4 days/week in the weight room and my only cardio is walking the dogs because indoor cardio sucks.  If there is a difference in type of exercise here, I’m not aware of it because I’ve never bothered to look.  I would generally imagine that a combination of weights and cardio is ideal.
  3. A diet including plenty of fruits and vegetables.  Common sense but who knows what all nutrients, etc. play a role in all of this.  I’m not great with vegetables since they bore me but I generally get at least one serving with 3-4 pieces of fruit per day.
  4. Regular Vitamin D intake. They recommended 2k IU, I take 5k IU just because.
  5. Regular fish oil intake.  They recommended 2 grams of preformed fish oils (which would contain 600 mg of combined EPA/DHA generally) but I’ve taken 3 times that much forever (a dose of combined EPA/DHA of 1.8-3.0 grams per day is what I recommend in my books).  There is some limited data that this helps with a variety of mental illnesses although it’s mixed.

That’s really it (I take a basic multivitamin just because and use zinc and magnesium at bedtime to ensure good sleep) and most of what they recommended was stuff I was doing already.  They commented that part of why I may have avoided a complete hypomanic meltdown (as happened in late 2014) was due to my already existing habits.  I was already doing most of the things I should have been.

I should note, since I get asked about it all the time, that there is some *very limited* evidence that ketogenic diets help to control bipolar.  I actually find this interesting as the ketogenic diet was used clinically to control epilepsy and a lot of bipolar drugs started life as epilepsy treatment drugs.  This suggests some type of shared mechanism between the two.  I also find it ironic on top of that given that my first book was on ketogenic diets.  Beyond that, I haven’t yet had time to look into the topic in any detail.

However, I am not currently following one because I like carbohydrates and know that I wouldn’t follow one indefinitely.  It also wouldn’t support my weight training so I just stick with a moderate carb diet and take my lamictal (I’m also on Deplin since a genetic test showed that I don’t convert folate to methylfolate).  I’m sure someone will get up my ass about preferring a medication over a “natural” approach but, here’s the thing: good advice not followed is bad advice.

I know I won’t do a long-term keto diet and my med dose is very low with no sides.  So I take low-dose meds over a diet I know I won’t do.  If I were in a situation where the meds weren’t controlling my mood or the side effects were intractable, I’d consider sucking it up and doing keto.  Since neither of those are the case….

But the above is what I do which seems to be consistent with the research and is what my NP told me to do.  I won’t say more than that.   I’m in no way recommending what I do as what should be done and am simply reporting it from my personal experience.

That’s all folks.

Anaerobic Threshold for Running versus the Bike

Question: Question that I’ve been asking around and can’t find a good, solid answer: I recently did a metabolic test at my gym to determine my anaerobic threshold and my VO2 max. The trainer who conducted the test told me, as they tell everyone who takes the test, that my AT would be 10 bpm lower on a bike or in a cycle class than it was on the treadmill when I took the test. Why might that be true??

Answer: I should probably define at least one term so that the above question and my answer will even make sense. Anaerobic threshold, which is often equated or called lactate threshold, OBLA, ventilatory threshold and probably others (note: technically these all describe slightly different things but they are conceptually similar enough that the distinction isn’t relevant) is a term that has been floating around for a good 40 years and is usually taken to indicate the period where an exerciser shifts from primarily aerobic to anaerobic metabolism.

Now, for a variety of reasons I don’t want to get into, this turns out to be a poor description of what’s going on, there is no abrupt switch from aerobic to anaerobic metabolism and scientists have been very busy not only studying the topic, but arguing with each other about what in the hell is actually going on. The same can be said for the other concepts I listed above such as lactate threshold; originally conceptualized at the point where lactate starts accumulating massively and causing fatigue….well, it’s more complicated than that. But all of this is physiological pedantry that even I get bored with. And that takes a lot.

Ultimately, the mechanism or nomenclature of what’s going on isn’t what I think is important; the practical implications are what are valuable here. And practically speaking, all of the above concepts (AT, LT, OBLA, VT) essentially represent the following: the highest exercise intensity that can be sustained for extended periods of time without rapid fatigue.

So consider someone who has a (pick one) AT, LT, OBLA, VT while running 10mph. Conceptually they should be able to run 10mph for quite some time (various cutoffs such as an hour are often thrown around, at least in cycling). It might be a hell of an effort but it can be done. Below that speed and the duration that can be sustained goes up and up. But above that (say 11 mph), fatigue will set in fairly quickly. Hopefully that makes sense.

AT, etc. are tested in a variety of ways but all ultimately attempt to determine the maximum intensity that can be sustained for extended periods without fatigue. As above, what you call this or think it represents is a lot less important in my mind than what it practically represents. So, back to the question: the trainer in question claimed that AT on a bike will be lower than while running, following what I presume to be a running test. Frankly, I’m not 100% sure that this is true but, searching through my resources, I can’t find anything either way on the topic.

Different types of training will show different lactate levels at the same percentage of VO2 max (my own sport, speedskating, shows the highest lactate levels at any given percentage of VO2) and that would tend to imply differences between activities. That is, there is generally a decent relationship between percentage of VO2 max. and heart rate and if there are then differences in lactate accumulation at a given percentage VO2, you’d expect that to end up showing a difference in heart rate at that level.

A better question might be why this is the case. Part of it is simply specificity, folks tend to test better in the activities that they typically do. So if you have an athlete who runs all the time, and you test their AT on a bike, they will show a much lower value than if you tested them on running. Beyond that, the only physiological reason I can think of why running might show a higher heart rate at AT, etc. would be that more muscle mass is active, several pieces of research certainly support this.

For example, comparisons of rowing (using a large muscle mass, including both upper and lower body) to cycling or speed skating show a higher maximal lactate steady state (MLSS, another concept akin to AT, LT, etc. above) for rowing. Probably due to the greater amount of muscle mass being utilized. In cycling, only the legs are moving (unless you’re doing something very strange on the bike), in running the upper body is active and this might shift the relationship between HR and LT. Will it be exactly 10 beats? I honestly can’t say.

Tempo Running and Endurance

I’ve been reading your blogs about steady state vs. interval training and they have been quite eye opening. In your article, “pole vault your way to a hot body” you talked a lot about tempo work in 400m runners. My question is, is this tempo running in kind of a low intensity interval training type situation better than long distance duration runs. If so, what is the science behind it? The way I have learned is your body begins to burn fat for fuel after about 15 minutes of aerobic work when it reaches the high oxygen consumption it needs to burn the fat. So to me, it seems like a good hour long run would yield better fat loss results than anything else.


The thing to keep in mind about the ‘extensive tempo’ running that sprinters commonly do is that the goal is not specifically aimed at fat loss (even if keeping the athletes lean is often a consequence of that type of training). Rather, it’s a way to get a large volume of relatively lower intensity work (to build work capacity, recovery, etc) while also getting in some technical work without having to slog endless miles.

Much of this reflects the odd situation that sprinters, and this is especially true in the middle distances of 400-800m have to deal with. They need the high power output for top speed but they also need the aerobic development and endurance that will allow them to

1. Be able to handle the high training volumes

‘2. Not run out of gas towards the end of the race

This puts them in a strange place metabolically, too much endless endurance work tends to compromise top speed and power output. But they need the aerobic development for the reasons stated above. Tangentially, it’s turning out (and cutting edge coaches have known this for years) that the size of the aerobic engine has a huge impact on how well the body handles acid generation during high-intensity activity.

Mitochondria actually have lactate transporters and having better developed aerobic capacity ends up improving anaerobic capacity as well. And developing this capacity takes much less out of the athlete then grinding out lots of anaerobic style intervals (which tend to be mentally and physically exhausting). As far as the fat loss question, the thing to remember is that typically the rest intervals are kept fairly short during this type of extensive tempo training. You reach a pseudo-aerobic steady state of sorts because you’re not getting complete rests between sets.

Which would explain a lot of why it has the effects that it has. Since the speed of the ‘on’ bits is also faster, it’s probably a bit more specific to the requirements of a 400m sprinter than slogging slow miles (although, as noted in one of my blog posts, they do some s as well). But the overall stress of the workout still tends to be towards the lower intensity end of things since the run bits are kept short.

Will it necessarily be “better” than an hour hard run? Probably not because, if nothing else, the hour run will burn far more calories (which is still the ultimate determinant of fat loss) than a 30 minute tempo session or what have you. But, as noted above, it’s more specific to what those distance sprinters need and the volume will, as a consequence, help to keep them leaner. Hope that clears things up.

Rapid Fat Loss without Weight Training

Question: I’m beginning a rehab program for a diastasis recti. I’m male, 58. I’m in fairly decent cardio shape (resting heartrate of 52 and can do 30 second intervals at 85-95% MHR; I try to do 15-20 minutes of variable paced warmup followed by the intervals and cooldown.)

However, I’m significantly overweight (6′ 220; ~35% body fat by a cheap scale) which is obviously a contributor to the diastasis. You can see why the idea of rapid fat loss is attractive.  The thing is, for the first 6 weeks on the diastasis program, strength
training is out of the picture.  I’m doing my cardio on a VersaClimber, which at least works my legs fairly well.

Would the rapid fat loss protocol work OK under these conditions? It sounds as though to try it I would need to put in more time on the climber and skip the intervals for the duration.

Answer: The short answer is that, at your current body fat percentage, yes, the Rapid Fat Loss Handbook program can be done without weight training.  This is an issue that I discuss in the book as well as in the article Initial Body Fat and Body Composition Changes but, simply, the higher your initial body fat percentage, the less muscle you are likely to lose under any circumstances (and by extension the leaner you are the more muscle you tend to lose, although this depends on a host of variables).   The primary function of resistance training on any diet is to maintain muscle mass but when the risk of muscle mass loss is reduced, the importance of weight training is lessened.

An additional factor, also discussed in the book is that there is often an increase in lean body mass (and this represents both muscle mass and connective tissue) when people gain body fat.  From the standpoint of obtaining a ‘normal’ body weight (whatever ‘normal’ means here) losing that ‘extra’ LBM is thought to be beneficial or necessary by some obesity experts.

Finally, at least in relative beginners, even cardiovascular exercise (and the Versaclimber is one of the rare machines that has both an upper and lower body component) has some effect on sparing muscle mass loss.  So the inclusion of that (although with volumes cut back to match the recommendations in the book) should be sufficient until you abdominal issue has healed and you can begin resistance training.

Hope that helps and good luck!

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