Tag Archives: muscle

Saturated fat, cholesterol, and carbohydrates

“You catch more flies with honey…”

^^^good policy in general, but especially for debating in the realm of nutritional sciences.

 

A short while back, Nina Teicholz discussed low carb ketogenic diets and plant-based diets with John Mackey.  Although I disagree with the dichotomy (keto vs. plant-based), it’s well-worth a watch:

 

 

Three topics that could not be avoided in such a discussion: saturated fat, cholesterol, and carbohydrates.

 

 

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Meal frequency, intermittent fasting, and dietary protein

Dietary protein “requirements” are some of the most context-dependent nutrient levels to decipher, and depend largely on energy balance and even meal frequency.

An objective look at intermittent fasting (Alan Aragon, 2007)

Meal frequency and energy balance (Lyle McDonald, 2008)

New study: “Increased meal frequency attenuates fat-free mass losses and some markers of health status with a portion-controlled weight loss diet” (Alencar et al., 2015)

This wasn’t well-received in social media because bro-science & many low carb advocates say grazing is no longer in vogue — “it’s much better/healthier/whatever to eat once or twice daily, because intermittent fasting and all that jazz” …however, this may be problematic when it comes to meeting overall protein needs, which is particularly important when you’re losing weight.

 

 

The study: 2 vs. 6 meals per day, crossover.  

Conclusion: “On average, fat-free mass (FFM) decreased by -3.3% following the 2 meals/d condition and, on average, and increased by 1.2% following the 6 meals/d condition (P<.05).”  

 

fat-free mass

 

In other words, 6 meals per day was better for body composition than 2 meals per day.  But context is everything, and this hypothesis has been tested from a variety of different angles, so what does it mean?  

The relevant context here: 1) big energy deficit (1200 kcal/d for obese women is a pretty low calorie intake); and 2) “adequateTM” protein intake (75 g/d).

The standard dogma says that in the context of an adequate protein hypocaloric diet, meal frequency matters a LOT, whereas with high protein, it doesn’t matter as much.  Theory being that with an “adequate” (read: too low?) overall protein intake, the fasting periods are simply too long with only two meals per day; you need either: 1) higher protein intake; 2) increased meal frequency; or 3) more calories (ie, smaller energy deficit).  

In this study, BOTH diets suppressed insulin and induced weight loss, but the increased protein feeding frequency skewed the weight loss to body fat while preserving fat-free mass.   I actually agree with a lot of the bro-science in this case, and also think that 75 grams of protein is not enough in the context of a big energy deficit (if body composition is a goal).    




 

Historical precedence?

 

Meal frequency and weight reduction of young women (Finkelstein et al., 1971)

Relevant context:  6 vs. 3 meals per day (3 meals per day may not seem like that many more than 2, but it significantly cuts down on the duration of time spent with no food or protein).

Smaller energy deficit: 1700 kcal/d in overweight patients is less of a deficit than 1200 kcal/d in obese patients.

Higher protein intake: 106 – 115g/d.

Result: nitrogen balance (a surrogate for the maintenance of muscle mass) and fat loss were similar in both groups.  This study fixed two problems in the abovementioned study: 1) 3 meals is better than 2 in the context of an energy deficit; and 2) protein intake was higher.

 

And again here, with 3 vs. 6 meals per day (Cameron et al., 2010), just to make the point that 3 meals per day is better than 2 for preserving lean mass in the context of an energy deficit.

 

The effect of meal frequency and protein concentration on the composition of the weight lost by obese subjects (Garrow et al., 1981)

This study tested the opposite extremes: super-low calorie intake (800 kcal/d), much lower protein intakes (20g – 30g/d), and 1 vs. 5 meals per day.

Result: “a diet with a high-protein concentration, fed as frequent small meals, is associated with better preservation of lean tissue than an isoenergetic diet with lower-protein concentration fed as fewer meals.”

It basically confirmed all of the above.

 

Protein feeding pattern does not affect protein retention in young women (Arnal et al., 2000)

1 vs. 4 meals per day; and 70 grams of protein but no energy deficit (~2000 kcal/d isn’t very hypocaloric for lean young women).  In this study, no effect of meal frequency was seen, likely because 70 grams of protein isn’t inadequate when energy intake isn’t restricted.

 

 

 

1. PROTEIN “NEEDS” ARE HIGHLY CONTEXT-DEPENDENT

2. NEED =/= OPTIMIZATION

3. MEAL FREQUENCY & meal timing and peripheral circadian clocks > “MACRONUTRIENTS”

 

If you’re losing weight (ie, in an energy deficit), then intermittent fasting is cool if protein intake is high (above “adequateTM“)… the bigger the energy deficit, the more protein is necessary to optimize changes in body composition.

 

How much is ‘enough?’  Sorry, can’t give you a gram or even gram per pound of body weight answer… but if you’re losing weight and seeing no discernible effect on body composition (muscle vs. fat mass), then it may be prudent to consider eating more protein-rich foods… and paying more attention to sleep quality (which also greatly impacts nutrient partitioning).

No amount of protein will help you if circadian rhythms aren’t intact!!!

 

 

further reading:

Yes, it’s a high protein diet (Tom Naughton, 2015)

Protein requirements, carbs, and nutrient partitioning

Dietary protein, ketosis, and appetite control 

 

 

calories proper

 

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Evolution stole this dude’s circadian rhythm

I got a laugh out of this one; not for the actual content, but because of how the authors worded their findings.  They sure love their fishies.

We have two very closely related fish, both Mexican tetra, Astyanax mexicanus, one with eyes who lives on the surface, and another who’s blind and lives in dark caves (“Pachon”).  It’s thought that they were the same species one day; divergent evolution.

 

note: eyeless

note: eyeless

The blind ones are circadian arrhythmic (Moran et al., 2014).  Surface-dwellers are more active during the day than night (blue line, left figure below), and their free-running circadian clock maintains this in the absence of photic input (blue line, right figure).  The blind ones, on the other hand, exhibit no circadian rhythm in the light or dark (orange lines):

 

Circadian rhythm metabolism

 

Cave-dwellers are circadian arrhythmic.  This is both in their natural photoperiod (ie, darkness) and in light-dark conditions (which is technically an environmental mismatch, but since they’re eyeless, it doesn’t really matter).

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Cyclical ketosis, glycogen depletion, and nutrient partitioning

Meal & exercise timing in the contexts of “damage control” and nutrient partitioning are frequent topics on this blog.  I generally opt for a pre-workout meal, but nutrient timing hasn’t panned out very well in the literature.  That’s probably why I’m open to the idea of resistance exercise in the fasted state.  A lot of pseudoscientific arguments can be made for both fed and fasted exercise, and since a few blog posts have already been dedicated to the former, this one will focus on the latter.

The pseudoscience explanation is something like this: since fatty acids are elevated when fasting, exercise in this condition will burn more fat; and chronically doing so will increase mitochondria #.  The lack of dietary carbs might enhance exercise-induced glycogen depletion, which itself would bias more post-workout calories toward glycogen synthesis / supercompensation.  Much of this is actually true, but has really only been validated for endurance training (eg, Stannard 2010, Van Proeyen 2011, & Trabelsi 2012; but not here Paoli 2011)… and the few times it’s been studied in the context of resistance exercise, no effect (eg, Moore 2007 & Trabelsi 2013).  However, there are some pretty interesting tidbits (beyond the pseudoscience) which suggest how/why it might work, in the right context.

Exercising fasted or fed for fat loss?  Influence of food intake on RER and EPOC after a bout of endurance training (Paoli et al., 2011)

John Kiefer, an advocate of resistance exercise in the fasted state, mentioned: “the sympathetic nervous system responds quicker to fasted-exercise. You release adrenaline faster. Your body is more sensitive particularly to the fat burning properties of adrenaline and you get bigger rushes of adrenaline.”

Much of this is spot on.  That is, ketogenic dieting and glycogen depletion increase exercise-induced sympathetic activation and fat oxidation (eg, Jansson 1982, Langfort 1996, & Weltan 1998).

The question is: can this improve nutrient partitioning and physical performance?  Magic 8-Ball says: “Signs point to yes.”  I concur.

Contrary to popular beliefs, glycogen depletion per se doesn’t harm many aspects of physical performance.  A lot of fuel systems are at play; you don’t need a full tank of glycogen.

Effect of low-carbohydrate-ketogenic diet on metabolic and hormonal responses to graded exercise in men (Langfort et al., 1996)

High-intensity exercise performance is not impaired by low intramuscular glycogen (Symons & Jacobs, 1989)

Increased fat oxidation compensates for reduced glycogen at lower exercise intensities (eg, Zderic 2004), and ketoadaptation may do the same at higher intensities.

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Carb Back-Loading, take II

I recently had the pleasure of speaking with John Kiefer and his crew about Carb Back-Loading proper; we discussed the protocol and many other hormonal effects associated with this pattern of nutrient & exercise timing.  Interesting stuff; plenty of fodder for future blog posts…

Brief refresher: skeletal muscle insulin sensitivity is higher in the morning than in the evening.  Exercise boosts insulin sensitivity selectively in muscle, which is relatively more important in the evening.  Thus, an evening carb-load may benefit from exercise to effectively partition the energy influx into skeletal muscle [and away from adipose tissue].

Summary of Part 1 of my CBL review: studies on nutrient timing sans exercise aren’t entirely consistent, in part, due to reciprocal regulation of insulin sensitivity in skeletal muscle and adipose tissue.  That is, excess energy from an evening carb-load, without the exercise-induced, skeletal muscle-specific boost in insulin sensitivity, may be biased less toward muscle growth and more toward fat storage, because unlike skeletal muscle, the sensitivity of adipose tissue to insulin appears to improve as the day progresses… and without exercise to offset this, as in the studies discussed below, this may lead to suboptimal results.

*one thing Kiefer stressed, and I agree, is that the effects of any given intervention may be population-specific.  For example, he pointed out that diurnal insulin sensitivity is less robust in obese and aged populations.  So if two findings aren’t in full agreement, click the link to the study and check this first… context matters!

 

 

Tl;dr: I think high intensity exercise and possibly the time of day it’s performed, and regular bouts of fasting, are important factors that mediate the efficacy of CBL and similar protocols. Continue reading

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Carb Back-Loading and the Circadian Regulation of Metabolism

Carb Back-Loading (CBL) redux, part I

Step 1: eat little in the morning (maybe some fat+protein; definitely no carb)
Step 2: exercise in the afternoon/evening
Step 3: eat the carbs, all of them.  Preferably high glycemic carbs.
Other: no dietary fat post-workout; protein periodically throughout the day.

What makes CBL different from its predecessors is the stress on the timing – exercise and carbs in the evening.  John Berardi’s “Massive Eating” dietary guidelines are similar: protein+fat meals all day except pre- and post-workout, which are protein+carb meals.  Martin Berkan’s “LeanGains” is fasting most of the time (including pre-workout), exercise in the afternoon, then a big post-workout meal (quite similar to CBL).  My only tweak, as discussed below (and previously here and here), would be a pre- rather than post-workout meal [in some contexts].

There’s a summary of this blog post at the bottom… it might be helpful to read that first (see: “Tl;dr:”).  Also, please note that much of this post is about the fringe of theoretically optimizing nutrient partitioning, like improving from 85 to 90%, or 40 to 45%, not 40 to 90%…  I’m not that deluded.

My initial take, in general, is that this book is loaded with gems about nutrition, exercise, biochemistry, and physiology.  It’s also very readable and has a lot of good recommendations.  In this post, I want to discuss one specific aspect of CBL: tissue-specific circadian regulation of metabolism.

 

nutrient timing

 

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More on physical performance and ketoadaptation

The various studies on how low carbohydrate diets impact physical performance are very nuanced.  Here’s what I mean by that.

Exhibit A. Phinney 1980

Phinney 1980

In this [pioneering] study, obese patients were subjected to a variety of performance assessments in a baseline period, then after 1 and 6 weeks of weight loss via protein-sparing modified fast (1.2 g/kg ideal body weight from lean meat, fish, or fowl; probably around 80 grams of protein/d, 500-750 kcal/d). They lost a lot of weight, 23 pounds on average, two-thirds of which was body fat. There was no exercise intervention, just the performance assessments.

During the ‘exercise to exhaustion’ treadmill exercise, RQ steadily declined from baseline to week 1 to week 6, indicating progressively more reliance on fat oxidation.  This was confirmed via muscle glycogen levels pre- and post-exercise: during the baseline testing, they declined by 15%; after 6 weeks of ketoadaptation, however, they only declined by 2%, while ‘time to exhaustion’ increased by 55%.  After only 1 week of the diet, time to exhaustion plummeted, as expected, by 20%.

This was, as mentioned above, a pioneering study in the field of ketoadaptation. It also challenges one of the prevailing theories of ‘fatigue’ …while carb-adapted, the subjects fatigued after 168 minutes, with muscle glycogen levels of 1.29 (reduced by 15%); while ketoadapted, they fatigued after 249 minutes with muscle glycogen levels of 1.02 (reduced by 2%).  In other words, they had less glycogen to begin with, used less glycogen during exercise, and performed significantly better (running on fat & ketones).

Exhibit B. Vogt 2003

Highly trained endurance athletes followed a high fat (53% fat, 32% carbs) or high carb (17% fat, 68% carbs) diet for 5 weeks in a randomized crossover study. In contrast to Phinney’s study, these participants were: 1) highly trained; and 2) exercised throughout the study.

Maximal power output and VO2max during a similar ‘time to exhaustion’ test was similar after both diet periods.  Same for total work output during a 20 minute ‘all-out’ cycling time trial and half-marathon running time.  Muscle glycogen was modestly, albeit statistically non-significantly lower after ketoadaption; however, ketoadapted athletes relied on a higher proportion of fat oxidation to fuel performance as indicated by lower RQ at every level of exercise intensity:

Vogt RQ

Again, this is the essence of ketoadaptation. Physical performance as good as or better using fat and fat-derived fuels.

One reason Phinney’s glycogen-depeleted ketoadapted subjects may have done so well is their reliance on ketones (probable) and intramyocellular lipids (IMCL) (possible).  In Vogt’s study, IMCL increased from 0.69 to 1.54% after ketoadaptation…

Also, food intake and body fat declined, and training volume increased in the low fat group; whereas food intake increased, and body fat and training volume declined in the high fat group.  Reminiscent of anything?

High fat, low carb -> eat more, exercise less, STILL LOSE BODY FAT.

Vogt data

Sorcery?  No.  Diet impacts more than just mood and body composition – resting energy expenditure increased in the ketogenic dieters.  This isn’t an isolated finding.

Exhibit C. Fleming 2003 

This was another study in non-trained athletes, consuming high fat (61% fat) or control (25% fat) diets for 6 weeks.  The tests were the 30-second Wingate, to examine supramaximal performance, and a 45-minute timed ride, to examine submaximal performance.

This study differed from the previous two in several significant ways.  For starters, peak power output declined in both groups, slightly more so in the high fat group (-10% vs. -8%).  Furthermore, RQ didn’t wasn’t significantly lower during this test in the high fat group, which possibly suggests they weren’t properly ketoadapted.  In Phinney’s study, the large energy deficit ensured ketoadaptation; this study lacked that aspect, somewhat more similar to Vogt’s, although unlike Vogt’s, these participants weren’t athletes which presumably makes ketoadaptation more difficult.

There are many factors at play… I wasn’t kidding when I said these studies are very nuanced!

Exhibit D. the infamous, Paoli 2012 

These were ‘elite artistic gymnasts,’ who could likely beat you in a race running backwards.  The ketogenic phase consisted of 55% fat and much more protein than the control phase (39% fat; protein: 41% vs. 15%). The significantly higher protein content was modestly offset by slightly more calories in the control phase, which reduces the amount of protein required to maintain nitrogen balance.

In this study, performance was, for the most part, ‘maintained,’ with relative increases in a few of the tests; eg, the “legs closed barrier.”  Changes in body composition were more robust: significantly reduced body fat and increased lean body mass after 30 days of ketogenic dieting (with their normal exercise routine).

Paoli data

The major confounder in this study was the use of an herbal cocktail only in the ketogenic diet group; despite this, the results are largely in line with the other studies.  For more on this study, see here.

Exhibit E. the most dramatic one to date: Sawyer 2013 

Please see here for the details, but in brief, strength-trained athletes showed improvements in high intensity exercise performance after only 7 days of carbohydrate restriction.  The nuances of this particular study are discussed more here.

barbell

Collectively, these studies show that physical performance in both endurance and high intensity realms does not always suffer, can be maintained, and in some cases is improved by ketogenic dieting.  Important factors are duration (to ensure adequate ketoadaptation), energy balance, and regular physical activity (athletes and regular exercisers can adapt to burning fat much quicker than sedentary folks).

 

calories proper

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New study: high intensity exercise on a low carb diet.

Switch an athlete from their standard carbohydrate-rich diet to a low carb ketogenic one and suddenly performance tanks.  It is known.  Give them a few weeks to adapt, however, and it recovers.  This much was established for mainly endurance-related performance parameters by Steve Phinney and colleagues in the 1980’s (eg, Phinney et al., 1983).  Then, along came Antonio Paoli, Dominic D’Agostino, and others who showed a similar phenomenon in gymnasts, a population that routinely exercises at higher levels of intensity (Paoli et al., 2012).  Notably, in these studies the athletes were allowed adequate time to adapt to the new metabolic milieu – sometimes referred to as ketoadaptation.  Three weeks appears to be the minimum amount of time required for ketoadaptation; ie, studies of shorter duration generally show: low carb = poor physical performance.

…which is why I was surprised to see this one:

Effects of a short-term carbohydrate-restricted diet on strength and power performance (Sawyer et al., 2014)

These researchers subjected ~30 strength-trained individuals to a battery of performance assessments before and after 7 days of a low carb [ketogenic] diet.  Usually I would’ve stopped reading at this point because 7 days is too short.  But there were some nuances in the way this particular study was designed which piqued my interest.

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Nutrient Partitioning: …a *very* high protein diet.

Or: what happens when you eat a ton of protein?

RDA: 0.8 g/kg

Active individuals: 1.2-2.0 g/kg (via ISSN)
Comment (1): I think sedentary, physically inactive, and non-exercisers should be in this range to offset disuse atrophy.  And they should exercise.
Comment (2): Do athletes really need more protein than non-athletes?  They have exercise, a powerful anabolic stimulus.  More protein may improve performance or body composition, but they might not *need* it, in terms of nitrogen retention… there’s probably a study on this.

NEED =/= OPTIMIZATION

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Diet study: American Diabetes Association vs. Low Carb Ketogenic

A randomized pilot trial of a moderate carbohydrate diet compared to a very low carbohydrate diet in overweight or obese individuals with type 2 diabetes mellitus or prediabetes (Saslow et al., 2014)

Disclaimer: this study was not ground-breaking; it was confirmation of a phenomenon that is starting to become well-known, and soon to be the status quo. That is, advising an obese diabetic patient to reduce their carb intake consistently produces better results than advising them to follow a low fat, calorie restricted diet.

The two diets:

Moderate carbohydrate diet: 45-50% carbs; 45 grams per meal + three 15 gram snacks = 165 grams per day; low fat, calorie restricted (500 Calorie deficit).  Otherwise known as a “low fat diet (LFD).”

In their words: “Active Comparator: American Diabetes Association Diet.  Participants in the American Diabetes Association (ADA) diet group will receive standard ADA advice. The diet includes high-fiber foods (such as vegetables, fruits, whole grains, and legumes), low-fat dairy products, fresh fish, and foods low in saturated fat.

Very low carbohydrate diet: Ketogenic; <50 grams of carb per day, no calorie restriction, just a goal of blood ketones 0.5 – 3 mM.

In their words: “Experimental: Low Carbohydrate Diet.  Participants will be instructed to follow a low carbohydrate diet: carbohydrate intake 10-50 grams a day not including fiber. Foods permitted include: meats, poultry, fish, eggs, cheese, cream, some nuts and seeds, green leafy vegetables, and most other non-starchy vegetables. Because most individuals self-limit caloric intake, no calorie restriction will be recommended.

Both groups were advised to maintain their usual protein intake.

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