Tag Archives: exercise


Athletes who drop carbs cold turkey suddenly suck.  It is known.  

But with a smidge of stick-to-it-iveness, performance completely recovers, in virtually every.  measurable.  aspect.  

This was shown years and years ago, in a seminal study by Drs Phinney, Bistrian, Evans, Gervino, and Blackburn.

The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation (1983)

Normally, fatty acids fuel low intensity exercise and carbs fuel high.  This is because high intensity exercise requires a high rate of ATP production, and glycogen to lactate generates ATP faster than a speeding bullet.  This is what makes power.  Getting ATP from fatty acids is like draining maple syrup from trees [at first].

mito pic

However, go low carb for long enough and the syrup begins to flow like water.  I lack the time to show what “long enough” entails, but  4 out of 5 studies on low carb diets and performance that only last a few days will show this.  Ketoadaptation takes time; ~3 weeks.

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Biohacking holiday weight gain

What should you eat before the big feast?  (hint: eggs.)  And don’t try to compensate in advance by eating less, this will only make you hungrier.  Furthermore, foods in your regular diet are probably healthier than holiday fare, so you definitely don’t want to eat fewer healthy foods to make room for empty calories.

Tip 1. 

Variation in the effects of three different breakfast meals on subjective satiety and subsequent intake of energy at lunch and evening meal (Fallaize et al., 2012)

Participants were served only one of these for breakfast:

And given unlimited amounts of these for lunch and dinner:

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The faux-low carb mouse and a diatribe

The faux-low carb mouse

Hyperinsulinemia drives diet-induced obesity blah blah blah (Mehran et al., 2012)

The researchers generated a mouse with half as much insulin as normal mice.  Physiological insulin levels remain intact, but hyperinsulinemia is genetically inhibited.  For the sake of simplicity, we’ll call them “InsKO.”

When fed a high fat diet, normal mice become markedly hyperinsulinemic (pink line) whereas InsKO mice maintain relatively normal insulin levels (red line).  Blue lines are chow-fed mice; similar trend but less interesting.

divide and conquer

InsKO mice don’t get fat,

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Milo of Croton vs. concurrent training

Lesson 1.  Milo of Croton

Every day since a very young age, Milo would drape his calf over his shoulders and do his daily exercises.  As his calf grew, so did Milo’s strength.  Many years passed and by the time of the Olympic games, Milo’s calf had become a full-grown bull and Milo’s strength became unparalleled in all the land (or so the story goes).

This is how strength-training works.  Increasing the amount of weight you lift progressively, consistently, and frequently makes you stronger.

Lesson 2.  Concurrent training

Resistance training builds muscle and strength.  Endurance exercise is good for the heart, burns fat and muscle, but doesn’t make you stronger.  Endurance exercise hinders the gains reaped from resistance exercise, not vice versa.  Interpretation: runners should lift; lifters shouldn’t run (sprints don’t count).

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Metabolic rate per se

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Admittedly, the effect of diet on metabolic rate is small (i.e. statistically non-significant in most cases), but its incredible consistency across space and time suggest it could be true.  And given the difficulty of maintaining a reduced body weight after dieting, it might even be important.  The following studies are examples of widely differing subject populations in various metabolic conditions; yet the effects of diet on metabolic rate exhibit a phenomenal degree of similarity.

disclaimer: I don’t know what’s more important – metabolic rate per se, the diet behind it, or the resulting hormonal adaptations.  All of the diets that are associated with a higher metabolic rate are also predicted to result in lower insulin levels and higher fat oxidation.  Thus, we are left with a triumvirate of diet, hormonal milieu, and energy expenditure… all of which are important for body composition and quality of life.

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[ketogenic] elite artistic gymnasts

Before you say anything, “elite artistic gymnasts” could probably beat you in a race running backwards.  (with you running forwards.)  They are elite athletes.  And given a sufficient keto-adaptation period, they perform better sans carbs.

Ketogenic diet does not affect strength performance in elite artistic gymnasts  (Paoli et al., 2012)

This study looked at body composition and various performance measures before and after 30 days of a very low carbohydrate ketogenic diet (“VLCKD,” < 25 grams of carbohydrate per day) or a normal diet (“WD,” > 250 grams of carbs per day).  25 grams of carbs is very very low, less than Atkins and Kwasniewski.  On the other hand, 41% protein is pretty high.

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Nutrient timing, Op. 101

There is no longer a debate on the value of protein supplements for exercisers.  Now I’d like to make the case for protein timing, or more specifically the value of pre-workout protein supplementation.

Cribb and Hayes (2006) examined the two extremes of protein consumption: immediately before and after working out (“PRE-POST”) vs. 8 hours before and 8 hours after working out (early morning and late evening; “MOR-EVE”).  Each protein shake contained 40 grams protein, 43 grams glucose, and 7 grams creatine.  The subjects were recreational weight lifters, an interesting choice in terms of data interpretation.  I.e., novices are expected to see much greater gains from beginning a new exercise program than experienced exercisers.  Thus, any difference between the groups is expected to be greater.  For example: compare the difference between 5 and 10 to that of 1 and 2.  The relative difference (2x) is the same in both cases, but the absolute difference between 5 and 10 is significantly greater and thus easier to detect.  This stacked the odds against seeing a difference between treatments.  The advantage is that experienced lifters know how to do a high intensity workout, and the results are applicable to people who already exercise.

Notes on the wonders of energy balance:
The protein shakes added ~272 kcal to their total food intake, which caused them to eat less during the rest of the day.  Interestingly, food intake declined by 74 kcal in the PRE-POST group and over twice as much (172 kcal) in MOR-EVE.  Food intake declined in MOR-EVE because the extra calories were just floating around in the bloodstream and thus available to register lots of “excess energy” to the brain.  But the increase in muscle was 2x greater in PRE-POST than MOR-EVE; thus, the extra calories in PRE-POST were immediately invested in laying down new lean mass and therefore weren’t around to signal “excess energy” to the brain.

energy in energy out is bollocks

How the “energy in” is handled is critically important.  With regard to an energy excess, dessert before bedtime is stored as fat but the same amount of calories from protein before exercise are invested into muscle.

A calorie isn’t a calorie because body composition matters.

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adipose, horcrux of metabolism

You wanna burn fat?  ATGL (Adipocyte Triacylglycerol Lipase) is your man.  ATGL is responsible for breaking down fat, a necessary precondition for fat burning.  Mice lacking ATGL accumulate tons of fat: 20x more in the heart, 10x more in testis, 3x more in skeletal muscles, 2x more in the GI tract, etc., etc.  Not surprisingly, they’re overweight.

Part 1.  The importance of the ability to un-store fat: appetite, body composition, and insulin.

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the bang for your exercise bucks

Exercise causes weight loss when it’s accompanied by diet…  but then again, so does art lessons.  a continuation of “Exercise alone won’t cut it

Effect of an energy-restrictive diet, with or without exercise, on lean tissue mass, resting metabolic rate, cardiovascular risk factors, and bone in overweight postmenopausal women (Svendsen et al., 1993)

Svendsen divided postmenopausal women in their mid-fifties into three groups for 12 weeks: 1) diet; 2) diet + exercise; and 3) none of the above (a weight-maintenance control, kudos!).  Dieters went from eating 1800 to 1000 kcal/d of a high protein low fat diet.  The exercise consisted of 1.5 hours of aerobic and resistance training 3x per week.  The results, in a nutshell: dieting was effective (they lost weight).  Exercising was effective (fitness improved).  So how much additional benefit did exercise provide? Not much.  The diet alone group lost 21 pounds, while the diet + exercise group lost 23 pounds.  Is that worth 4.5 hours of high intensity exercise?  Body composition was mildly improved by the addition of exercise, as body fat percent declined 19% with diet + exercise and only 14% with diet alone.  But 4.5 hours of high intensity exercise is a LOT of work; and resting metabolic rate declined the most in the exercise group.  To its credit, exercise improved fitness considerably, which bodes well for quality of life, but just to keep it straight, diet alone reduced body weight by 21 pounds; exercise took off an additional 2 pounds… BUT as it turns out, those additional two pounds were probably also from diet, as the exercisers reduced food intake by an additional 57 kcal/d.  This doesn’t sound like much, but over the course of 12 weeks it adds up to 4788 kcal (that’s over a pound of fat mass).  In other words, exercise didn’t contribute to the weight loss.  The Laws of Energy Balance can be cruel.

Resistance training does not contribute to improving the metabolic profile after a 6-month weight loss program in overweight and obese postmenopausal women (Brochu et al., 2009)

Study design was similar to Svendsen’s (postmenopausal women, mid-fifties, etc.), with the exceptions that the diet was less strict and the exercise was resistance training, not aerobic (e.g., treadmill).  Dieting worked (both groups lost weight).  Exercising worked (they got significantly stronger).  So how much additional benefit did exercise provide?  You guessed it: not much.  The diet alone group lost 11 pounds; diet + exercisers lost 13 pounds.  3 sessions of high intensity exercise per week for 6 months led to 2 additional pounds of weight loss.  Unlike Svendsen’s exercisers, however, those two hard-earned pounds were probably due to the exercise, as metabolic rate and food intake declined to the same extent in both groups.  6 months of high intensity weight training for two pounds?  The Laws of Energy Balance: merciless.

Effect of diet and exercise, alone or combined, on weight and body composition in overweight-to-obese postmenopausal women (Foster-Schubert et al., 2012)

Saved the best for last: this study included both a weight maintenance control AND an “exercise only” group.  Kudos, Dr Foster-Schubert.  Study design was similar to Brochu’s and Svendsen’s: 12 months; moderate to high intensity aerobic exercise 3-5x per week, yada yada yada.  Dieting worked (the diet alone and diet + exercise groups lost weight).  Exercising worked (the exercise alone and diet + exercise groups got fitter).  So how much additional benefit did exercise provide?  Fail.  The dieters lost 16 pounds while the diet + exercise group lost 20 pounds.  The exercisers lost 4 pounds.  From those numbers, it might appear as though weight loss from exercise contributed mathematically to diet (4 + 16 = 20).  NOPE.  The exercisers cheated, by dieting :/
Exercisers reduced food intake by 185 kcal/d which amounts to a whopping 66600 kcal over the course of a year.  Theoretically, this could’ve amounted to a loss of over 15 pounds of fat mass.  But it didn’t.  Exercise caused a great enough reduction in metabolic rate to dwindle a 20 pound fat loss all the way down 4 pounds.  Exercise made them 16 pounds slothier.  And what about the diet + exercise group; they lost the most weight so surely exercise had to have added something to it?  NOPE, not here either.  They reduced their food intake more than any other group. The Laws of Energy Balance scoff at exercise.


So there you have it.  Trying to lose weight via exercise alone is like bringing a cup of water to a forest fire.  It is too easily compensated for by reductions in metabolic rate.  In studies spanning the course of 20 years, exercise has consistently failed to contribute to weight loss.  Exercisers lost weight if and only if they dieted.  Diet + exercise might be as effective as diet + art lessons or diet + Facebook, although the latter two are less likely to make you slothier.  Exercise will make you better, and maybe even happier, just not skinnier.

calories proper


Exercise-induced hunger attenuates exercise-induced energy deficit

and what we can’t learn from rodent studies.

Mandatory pre-reading: Exercise alone won’t cut it

It’s difficult to conduct experiments on energy balance in humans because they’re we’re all so diverse.  This is one reason why researchers use animal models; diet, exercise, and even genetic background can be rigorously controlled to a degree unimaginable in humans.  Despite all of this, however, exercise studies involving rodents are consistently inconsistent and inherently flawed.  They are not applicable to weight loss or energy balance in humans.  “Attention nutrition researchers, stop doing them.”

Exhibit A.  Cafeteria diet-induced insulin resistance is not associated with decreased insulin signaling or AMPK activity and is alleviated by physical training in rats (Brandt et al., 2010)

Three groups of rats: 1) chow-fed controls; 2) cafeteria-junk-food-diet; and 3) cafeteria-junk-food-diet + exercise.  The exercise was high intensity and consisting of swimming 5x per week with a tiny dumbbell attached to their tail (equal to 2% of their body weight).

In these lucky rats, exercise completely blunted weight gain, but did so, at least in part, via reduced food intake.  Exercise-induced anorexia might reflect the unnatural-ness of a rat subjected to a rigorous exercise protocol; it’s stressful for them.  Exercising rats are not happy thinking they’re doing something good for themselves; they’re trying to not drownAnd while exercise corrected their body weight, it failed to normalize fasting insulin (above) and glucose tolerance (which may also confirm they are stressed out):

Needless to say, in humans, it’s the exact opposite.  With exercise, food intake increases, body weight stays the same (usually), and insulin sensitivity is superbly enhanced.  But to further drive home the point that these studies should not be conducted with rodents, it’s not even consistently “the exact opposite.”

Exhibit B.  Effects of food pattern change and physical exercise on cafeteria diet-induced obesity in female rats (Goularte et al., 2012)

In this somewhat more complicated study, cafeteria diet-fed rats: 1) went on a diet; 2) started an exercise regimen; or 3)  both. 

In contrast to Brandt’s findings, exercise increased food intake and failed to reduce body weight (similar to unlucky subject number 9).  However, in agreement with Brandt, exercise failed to normalize insulin (above) and glucose tolerance:

One of the greatest metabolic benefits of exercise in humans, i.e., restoration of insulin sensitivity, is not reproduced in 2 rodent studies.

Unfortunately, the hypothesis that exercising rats is just like torturing rats was actually tested.

Exhibit C.  Effects of epinephrine, stress, and exercise on insulin secretion by the rat (Wright and Malaisse, 1968)Swimming had an effect on glucose and insulin that was strikingly similar to receiving foot shocks (i.e., electrocution).

And last but not least, to bring it around full circle, here’s how it is supposed to look:

Exhibits D, E, and F.  A 12-week aerobic exercise program reduces hepatic fat accumulation and insulin resistance in obese, Hispanic adolescents (van der Heijden et al., 2012)

Exercise protocol: cycling.  10 minutes warm-up, 30 minutes at 70% VO2peak (HR > 140 bpm), 10 minutes cooldown.  Only TWICE per week.

1) VO2peak significantly improved, confirming that this seemingly puny exercise routine had a real physiological impact.

2) Neither body weight nor fat mass declined, suggesting this was truly “exercise alone.”  I.e., they weren’t dieting.

3) HOMA-IR, a measure of insulin resistance, declined.

1+2+3 = exercise improves insulin sensitivity.

Effects of aerobic versus resistance exercise without caloric restriction on abdominal fat, intrahepatic lipid, and insulin sensitivity in obese adolescent boys (Lee et al., 2012)

Above: body weight didn’t change, confirming this was “exercise alone.”
Below: insulin sensitivity improved in both exercise groups.

It’s been almost 100 years, why can’t the rats get it right? (by “rats,” I mean scientists who tie weights to rats tails, throw them into a tub of water, and call it “exercise”).

calories proper