Bodyrecomposition Mailbag 4

Having written about what calories are, it’s time to return to the mailbag since this is always an easy way for me to get content.  Today I’ll address questions about heart rate monitors and metabolic rate, agronomist activity levels and calorie levels, NEAT and adaptive thermogenesis,  and then a long answer on the topic of whether to lose fat or gain muscle for a beginner at 20% bodyfat (if I were a different kind of writer I’d that THE ANSWER WILL SHOCK YOU!).

Heart Rate Monitoring and Metabolic Rate

Hey Lyle, Huge fan of your work, it really has changed my life… just wish I’d stumbled upon you a decade ago, I’d be a machine by now! Anyhow, I was just curious about your opinion on heart rate monitors and wether they can be an accurate way of monitoring your metabolism during a cut. I have a Fitbit charge hr which seems to do a pretty solid job. I.e. When I use it to cut I lose weight, bulk I gain weight and my weight is pretty damn stable when I use it to maintain. I’ve noticed that when I cut my resting pulse rate progressively gets lower over the course of the cut and also that I start to burn less and less calories during my workouts.


In at least a general sense, a drop in heart rate is pretty normal with dieting to lower levels.   For example, in a recent study that attempted to mimick the classic Minnesota Semi-Starvation study, men first overfed for one week before were placed on a 50% calorie reduction for three weeks.  In addition to changes in other metabolic parameters, heart rate went up from 65 to 68 Beats Per Minute (BPM) during overfeeding and dropped to 59 BPM during calorie restriction.    In a yet to be unpublished case study of contest dieting in a male bodybuilder, heart rate dropped by 9 BPM over 16 weeks along with metabolic rate and other hormonal factors.  Given that sympathetic nervous system output declines on a diet, and this is certainly part of the control of resting heart rate, this makes a great deal of sense.

So yes, it is at least qualitatively indicative although I’m don’t think you can use it to quantify how much metabolic rate has dropped specifically.


Bodyrecomposition Mailbag 3

So another dig into the mailbag to save myself having to think of another feature article to write.  The three questions today have to do with fat loss and muscle sparing, phosphatidylserine, cortisol and water retention.   Finally is a look at causes of a plateau in weight gain.

Dietary Deficit and Fat Loss when Muscle Sparing is the Same

Hi Lyle. A nerd question: Since the only two things in human body which can: 1. store energy 2. be able to gain and loss in a huge range all year long (compare to glycogen which could only be gained and lost in a small range), are fat and muscle (is that ture?). So is that true all diet would result in exactly the same amount of fat loss, if 1. the deficit is the same and 2. the muscle loss or protection is the same? Ignoring all other factors like insulin level?


Short answer: yes-ish and I say that as I’m going to actually address a question that you didn’t actually ask.

Sort of by definition if the total actual tissue loss is the same and lean body mass (LBM) sparing is identical, actual fat loss will be the same.  It has to be.  If 10 total pounds of tissue is lost and both diets only allow 1 pound of LBM loss, the other 9 lbs has to be fat (ok, something truly screwy could go on such as loss of bone or organ mass but it’s usually pretty small).

Now, if you want to be pedantic and look at weight loss, this isn’t necessarily true.  This is why I was using the odd term tissue loss.  Because part of total weight loss is not actual tissue loss but things like glycogen, water, food in the gastrointestinal tract and such.  Those will vary depending on diet, a low-carbohydrate diet will cause glycogen to become depleted, water and minerals to be lost and since carbohydrates are the primary source of the food residue that comes out the other end, that will also be decreased. Ketogenic diets may cause a loss of water weight of 1-15 lbs in the first several days for example.


More from the Mailbag

Ok, I know I promised something special last week but with all of the grinding and gnashing of teeth over the election, I would hate for it to get lost in the noise.  So instead I’ll throw a quick mailbag together which I don’t mind getting lost in that noise.  In today’s questions, I’ll address the idea of reverse cyclical dieting for mass gains, DB’s for growth, muscle gain and metabolic rate in beginners, artificial sweeteners and gut health and yohimbine and water retention.

Reverse Cyclical Dieting for Mass and DBs for Growth

I was thinking if you do like eat 2700-2800 calories or 200-300 calories surplus on Wednesday through Sunday, that could increase muscle growth, because you are in a surplus while muscle protein synthesis is right there.  But you also fast with a ton of protein on Monday/Tuesday so can’t see why you would break down muscles.

also are dumbbell exercises only, a huge problem in the long run for a natural bodybuilder?, like you get up to a 100kg bench press and like 100kg lunges and stuff, but squat is harder to do, but not all bodybuilder squat that have big legs i have heard.

Ok so there’s two questions in the above.  The first is about using Monday/Tuesday as essentially Protein Sparing Modified Fast Days (PSMF, my Rapid Fat Loss Handbook) and I assume he’s asking about doing such to limit fat gains (if he’s asking something else, I’m unclear).

This actually isn’t a new idea, I believe it was Fred Hatfield who first put this out there suggesting to train and eat at a surplus for 5 days and then diet for 2 days.  For whatever reason, it never seemed to catch on.  I’d also point out that as protein synthesis can run up to 36 hours and fasting on Saturday could limit growth from Friday.  So a single day fast might be better here and there is a recent article in the NSCA journal suggesting that athletes who need to keep bodyweight/bodyfat in check might benefit from such a strategy. I’d be inclined to start with a 6/1 pattern.


Dipping into the Bodyrecomposition Mailbag 2

Since I can’t think of any fascinatingly tedious topic to address this week, I’ll go the lazy route and just go with some questions instead.  Always easier when someone else gives you your topic.

BCAA and Anxiety
Hello, I am trying to treat mild anxiety, fatigue and depression with diet and supplements. I have removed processed foods from my diet, largely removed refined sugar and upped my greens and wholegrain. I am maintaining a good amount of healthy carbohydrates – I read that too little can affect cortisol levels negatively(?). I have also started taking 5g of BCAA every morning and I take Vit B complex every evening. I am not sure if what I am doing is okay? In particular the BCAA -I am reading a lot about tyrosine and phenylalanine and tryptophan – – I am not sure if I am getting these in BCAA, or if I should be getting them!? I would appreciate any advice.

I have addressed this topic in some detail previously on the site but it’s worth revisiting.   BCAA is an abbreviation for the branched-chain amino acids (so named due to their chemical structure) which are leucine, isoleucine and valine and nothing more.  And not only do I not see a role for BCAA in treating depression and anxiety, I think it could actually be detrimental in this case. The reason is detailed in the above link but, briefly, the BCAA and the amino acid trytophan (which is a precursor to serotonin) compete for the same transporter in the brain.  So if there are lots of BCAA floating around, tryptophan uptake is reduced.  This is part of why eating carbs makes you sleepy (and soften calmer, and it does lower cortisol): insulin pushes BCAA into muscle leaving less in the blood stream; this means that tryptophan can get into the brain and do it’s job.

Basically, it would be better to supplement with tryptophan (or 5-HTP, 5 hydroxytroptophan which is just a step closer to serotonin) than BCAA in this regard.  I’d point you to for information on dosing and effects.


Digging into the Bodyrecomposition Mailbag

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.

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.

Question: I was wondering if you could make sense of this article in terms of what you know about human metabolism:

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: