Tag Archives: diet

Skipping meals, intermittent fasting, grazing, etc.

or… Circadian Meal Timing!

They say if you’re going to [intentionally] skip a meal, it should be breakfast – and hey, that’s probably the easiest meal to skip.  However, a recent study showed skipping dinner FTW (well, not exactly).  I’ve never seen a proper study directly comparing the effects of skipping different meals, but here are a few that come close.  The findings may surprise you.

omelette

note: with the exception of Fernemark (Exhibit B), these studies are mostly macronutrient-controlled. That is, protein, fat, and carbs are similar between the groups; the only thing that differs is when they were ingested.  This can be tricky and/or very nuanced in some instances, like if dinner was smaller (fewer calories) but more protein-rich, for example… but in order to include 5 relevant studies and not bore you to death, you’ll have to check the full texts for those details.

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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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Melatonin is the chemical expression of darkness.

Melatonin is secreted from the pineal gland, the seat of the soul, the third eye.   Pinealectomy induces circadian arrhythmia and has interesting effects on adipose tissue biology.

Exhibit A.  In 2004, Alonso-Vale and colleagues showed that 6 weeks after pinealectomy, [melatonin-deficient] rats subjected to fasting exhibited an impaired energy conservation response.  That is, they lost more weight and significantly depleted their adipocytes:

pinealectomy

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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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Circadian disruptions impact behavior and metabolism in a tissue-specific manner.

The control of circadian gene expression is complex, with layer upon layer of suppressors and enhancers, numerous transcription factors, and a lot of interactions.  A gross oversimplification: Clock and Bmal1 are positive regulators of circadian gene expression; Per and Cry are negative (you don’t really need to know any of this).

 

Some pretty cool progress has been made in examining the effects of global and tissue-specific deletion of circadian rhythm-related transcription factors.  Bear with me :)

For example, global Bmal1 knockout mice (ie, mice that don’t express Bmal1 anywhere in their whole body.  Zero Bmal1.  Nil.) (Lamia et al., 2008).  These mice are obese, and exhibit impaired glucose tolerance yet improved insulin sensitivity.

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Does junk food make you lazy?

From Times LIVE: “Does junk food make you lazy?” 

“A diet rich in processed foods and fat – and the extra weight that comes along with it – may actually cause fatigue, a lack of motivation and decreased performance, according to a recent study involving lab rats… excessive consumption of processed and fat-rich foods affects our motivation as well as our overall health.”

(this is categorically false as both diets used in the study being discussed were very low in fat.)

And from Psych Central: “Rat study shows junk food can make you lazy

The theory itself isn’t too far-fetched: a crap diet can cause weight gain and reduced energy expenditure, or a tendency to minimize any kind of physical activity… instead of: “’laziness’ causes obesity.”  And whether or not it’s true, unlike what some would have you believe, this wasn’t the study to prove it.

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Meat digestion – fresh and raw or medium rare.

“If a dog team is worked hard daily for two weeks and fed with fresh fish caught under the ice and frozen without opportunity of becoming high, that team will lose weight and show definite signs of wear and tear.  If the team is fed with hung or high fish, they will be as good at the end of that time as the start, and often will have put on a little weight.”

-quote from a cool book Duck Dodgers sent me about digestive enzymes. 

“High” doesn’t mean psychedelic, but rather letting the meat sit for a time so as to allow it to tenderize, or “pre-digest.”

One study showed that protein breakdown, measured by desmin degradation, increased by roughly 33% if the meat was removed from the cow 24 hours after slaughter (“conventional”) instead of immediately after (“rapid”) (King et al., 2003).

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Animal fibre

Fruits and veggies, fermented or otherwise, aren’t the only source of prebiotics in your diet.  Eat a whole sardine and some of the ligaments, tendons, bones, and cartilage will surely escape digestion to reach the distal intestine where they will be fermented by the resident microbes.  

sardines

Salmon skin and the collagen in its flesh, the tendons that hold rib meat to the bone, and maybe even some of the ligaments between chicken bones.  All of these are potential prebiotics or “animal fibres.”  And it may explain why fermented sausages are such good vessels for probiotics.


 
“Animal prebiotic” may be a more appropriate term because the food matrix is quite different from that of non-digestible plant polysaccharides.  And while I doubt those following carnivorous diets are dining exclusively on steak, these studies suggest it might be particularly important to eat a variety of animal products (as well as greens, nuts, dark chocolate, fermented foods, etc.) in order to optimize gut health.

almonds

These studies are about the prebiotics in a cheetah’s diet.  Cheetah’s are carnivores, and as such, they dine on rabbits, not rabbit food.

cheetah

As somewhat of a proof of concept study, Depauw and colleagues tried fermenting a variety of relatively non-digestible animal parts with cheetah fecal microbes (2012).  Many of the substrates are things that are likely present in our diet (whether we know it or not).

Cartilage

Collagen (tendons, ligaments, skin, cartilage, bones, etc.)

Glucosamine-chondroitin (cartilage)

Glucosamine (chitin from shrimp exoskeleton? exo bars made with cricket flour?)

Rabbit bone, hair, and skin (Chicken McNuggets?)

Depauw ferments

The positive control, fructooligosaccharides (FOS), was clearly the most fermentable substrate; however, glucosamine and chondroitin weren’t too far behind.  Chicken cartilage and collagen were also well above the negative control (cellulose).  Rabbit skin, hair, and bone weren’t particularly good substrates.

As to fermentation products, collagen, glucosamine, and chondroitin were actually on par with FOS in terms of butyrate production:

Depauw SCFAs

Glycosaminoglycans (glucosamine and chondroitin) are found in cartilage and connective tissues (ligaments and tendons) and may have been mediating some of these effects as they’re some of the carbiest parts of animal products.  Duck Dodgers wrote about this in a guest post at FTA and in the comments of Norm Robillard’s article (probably elsewhere, too); very interesting stuff.

The authors also mentioned that the different fermentation rates in the first few hours suggests an adaptive component (some took a while to get going), or that certain substrates induced the proliferation of specific microbes.  “Animal prebiotics.”

Depauw close up

This is particularly noticeable for FOS (solid line), which is a plant fibre that wouldn’t really be present at high levels in a cheetah’s diet, so the microbes necessary to ferment it were probably not very abundant (initially).  Chicken cartilage (long dashes), on the other hand, started immediately rapidly fermenting, perhaps because this is more abundant in the cheetah’s diet.


 
Depauw took this a step further and fed cheetahs either exclusively beef or whole rabbit for a month (2013). Presumably, the beef had much less animal fibre than whole rabbit.  When they initially examined fecal short chain fatty acids, there were no major differences between the groups:

SCFAs per gram

However, if you take into consideration that the whole rabbit-fed cheetahs produced over 50% more crap than meat-fed cheetahs, then some other differences become apparent.  For example, the concentration of total SCFAs is actually greater in the feces from whole rabbit-fed cheetahs:

updated table

edit: la Frite pointed out that the table in the original manuscript is incorrect; the total SCFA numbers are reversed. The excel table above is corrected.

Further, the mere fact that there was 50% more fecal mass per day pretty much confirms way more animal fibre in whole rabbits.  And while neither of these studies were accompanied by microbial analysis, a more recent study on cheetahs fed primarily meat, “randomly interspersed with unsupplemented whole rabbits,” showed low levels of Bacteroidetes and Bifidobacteria, two potentially health-promoting groups of microbes (Becker et al., 2014).  I suspect this may have been at least partially due to a relative lack of animal fibre, compared to the Depauw’s exclusive whole rabbit diet.

Human digestive physiology and gut microbes are certainly far different from that of a cheetah, but maybe we too receive some prebiotic benefits from these animal fibres… just something to think about next time you’re eating sardines or pork ribs.

calories proper

 

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Insulin, sympathetic nervous system, and nutrient timing.

Insulin secretion is attenuated by sympathetic nervous system activity; eg, via exercise.  Theoretically, exercising after a meal should blunt insulin secretion and I don’t think this will lessen the benefits of exercise, but rather enhance nutrient partitioning.   And this isn’t about the [mythical?] post-workout “anabolic window.”

Sympathetic innervation of pancreas: norepinephrine –> adrenergic receptor activation = decreased insulin secretion & increased lipolysis (Stich et al., 1999):

Stich insulin

Stich CAS

note how quickly catecholamines are cleared upon exercise cessation

Stich NEFA

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Insulin, dietary fat, and calories: context matters!

Jane Plain recently wrote a great article about the relationship between insulin, dietary fat, and calories.  There are a lot of data on this topic, which collectively suggest: context matters! 

For example,

Insulin and ketone responses to ingestion of MCTs and LCTs in man. (Pi-Sunyer et al., 1969)

14 healthy subjects, overnight fasted; dose: 1g/kg.

In brief, MCTs are more insulinogenic than corn oil.  But it’s not a lot of insulin.  Really.  Enough to inhibit lipolysis, perhaps, but that’s not saying much… & certainly not enough to induce hypoglycemia.

Pi-Sunyer MCT Corn oil

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