Category Archives: Energy balance

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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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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Carbohydrates, calories, appetite, and body weight.

The Optimal Diet, Atkins, South Beach, Paleo, Zone… all have one thing in common: some degree of carbohydrate restriction.

Low, lower, lowest: does it matter?

There are 4 relatively large, randomized ‘diet-induced weight loss’ studies that all reported fairly comprehensive food intake and body composition data. The studies ranged in duration from 24 weeks to one year and included anywhere between 50 and ~300 overweight and obese participants.

In general, participants assigned to the low fat intervention were advised to restrict calories and fat whereas those assigned to low carb were told they could eat as much as they wanted as long as it wasn’t carbs.

Your mileage may vary – but these studies cover a large number of subjects from a wide range of backgrounds, suggesting the results might be applicable across the board.  Conclusion?  the amount of body fat lost was much more strongly associated with the reduction in carbohydrates than calories.  The only modestly surprising aspect was the magnitude… (see the figures below).

The four studies, in chronological order:

Brehm 2003: over the course of 6 months, those who consumed an average of 163 grams of carbohydrate per day lost 8.6 pounds of body weight while those who consumed 97 grams lost 18.7 pounds.

McAuley 2005: 24 weeks; those who ate 171 grams lost 10.3 pounds, while those who ate 133 grams lost 15.2 pounds, and those who ate 107 grams lost 15.6 pounds.

Maki 2007: 36 weeks; those who ate 186 grams lost 5.7 pounds, those who ate 131 grams lost 9.9 pounds.

Gardner 2007: 1 year – those who ate 138 grams lost 10.3 pounds, 181 grams lost 3.5 pounds, 195 grams lost 4.8 pounds, and 197 grams lost 5.7 pounds.

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Impact of a low-carbohydrate, high-fat diet on gut microbiota.

NPR recently reported on a study where the participants ate either a meat-based, fiber-free ketogenic diet or a vegetarian diet and had their gut microflora analyzed.  The low carb diet was much higher in fat, and as such, increased the prevalence of a microbe involved in fat digestion.  “Bilophila.”  The article focused on this one and cited a 2012 study where Bilophila was associated with intestinal inflammation… however, the ketogenic diet increased the levels of Bacteroides and decreased Firmicutes.  These are the two that brought the whole gut microbe-obesity connection into the spotlight.  The microbiome in obese mice is characterized by low Bacteriodetes and high Firmicutes. Fecal transplants from obese mice to lean mice causes them to gain weight.  Little is known about Bilophila relative to Bacteriodetes & Firmicutes, and I suspect the focus was on Bilophila because the authors wanted something negative to say about a meat-based, fiber-free ketogenic diet, and that 2012 mouse study suggested Bilophila could be their answer.

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Dietary protein, ketosis, and appetite control.

Dietary protein has a purpose, and that purpose is not carbs.”  Nor is it to break ketosis or stall weight loss.  

Drastically increasing protein intake may reduce the degree of ketosis in the context of a large energy surplus, but this is likely due more specifically to the large energy surplus than the protein.  This would explain why Warrior dieters (1 meal meal per day) often report reduced ketones if they eat too much protein.  It’s more likely that the 2000 kcal bolus is exerting it’s anti-ketotic effect by being a large energy surplus, such that anything other than 90% fat would blunt ketosis.  It’s not the proteins… Want proof?  Here’s an n=1 to try: give up Warrior dieting for a few days and try 3 squares.  My bet is that you’ll be able to increase protein intake and still register ketones as high or higher than before.  There are data to support this and reasons why it may not matter (below).

disclaimer: I don’t think “deep ketosis” is necessary to reap the benefits of carbohydrate-restriction.  But if you love high ketone meter readings, then this might be a better strategy to maintain deep ketosis while getting adequate protein. win-win.

if I hear: “oh no, I was kicked out of ketosis!” one more time… 

All of the studies below are confounded one way or another, but so are we humans.

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Protein Leverage Hypothesis

Inverse Carb Leverage HypothesisTM

Protein Leverage Hypothesis: Dude eats 15% protein on a 2000 kcal diet (75 g protein).  Exchange 25 grams of protein with carb, and he’s now eating 10% protein on a 2000 kcal diet (50 g protein).  Theory states Dude will increase total food intake to get back those 25 grams.

Ergo, Protein Leverage Hypothesis:

protein leverage hypothesis

Disclaimer: I don’t care much for the Protein Leverage Hypothesis.  It might be true, but that doesn’t mean it matters.  It works well in rodents, but obese patients eat tons of protein.  The rebuttal to this is that the protein in their diet is too diluted with other [empty] calories.  They’re overeating because of low protein %.

The flipside, confirmed ad nauseam in rodent studies, is that frank protein deficiency increases food intake.  Frank protein deficiency means negative nitrogen balance & tissue loss… not just skeletal muscle; organs, too.  Incompatible with survival.

Feed someone a low protein low fat diet, they get hungry.  If it’s ad libitum, they eat more.

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The incredible camping experiment, circadian proper

Entrainment of the Human Circadian Clock to the Natural Light-Dark Cycle (Wright et al., 2013)

Abstract (edited): The electric light is one of the most important human inventions. Sleep and other daily rhythms in physiology and behavior, however, evolved in the natural light-dark cycle, and electrical lighting is thought to have disrupted these rhythms. Yet how much the age of electrical lighting has altered the human circadian clock is unknown. Here we show that electrical lighting and the constructed environment is associated with reduced exposure to sunlight during the day, increased light exposure after sunset, and a delayed timing of the circadian clock as compared to a summer natural 14 hr 40 min:9 hr 20 min light-dark cycle camping. Furthermore, we find that after exposure to only natural light, the internal circadian clock synchronizes to solar time such that the beginning of the internal biological night occurs at sunset and the end of the internal biological night occurs before wake time just after sunrise

In other words, they compared circadian events during 2 weeks of normal life to 2 weeks of 100% camping.  And camping won.

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Summer is fattening. Don’t do it in winter.

Seasonal eating proper

More on seasonal eating in what appears to be the primary model for its justification for use in humans – hibernating mammals.

How it goes, or so they say: in summer, hibernators massively overeat, including carb-rich foods, in order to generate muscle and liver insulin resistance, so as to promote body fat growth.  The long light cycle reduces evening melatonin, which pushes back the usual nighttime peak in prolactin, which causes an abnormal resistance to leptin, which induces hypothalamic NPY and subsequent carbohydrate craving.  Ergo, summer is fattening.  In today’s day, increased artificial lights guarantee year-round pseudo-summer; and we no longer experience the benefits of the short light cycle: longer sleep times (akin to hibernation) and fasting – either complete fasting as in hibernation, or pseudo-fasting, ie, a ketogenic diet.

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Lights Out! Get your melatonin.

From T.S. Wiley’s website:
“People spent summers, before electric lights, sleeping less & eating heavily in preparation for winter because the light triggered the hunger for carbohydrates. Now, light is available 24 hours a day. Heating and air-conditioning climate control our hormonal responses to consume carbohydrates now available year round. This is the scenario for obesity, Type II diabetes, and depression… In Wiley’s opinion, sleep is the best medicine.”

And Wikipedia:
“Wiley’s main thesis in Lights Out is that light is a physiological trigger that controls dopamine and hormones like cortisol. Wiley posits that with the extension of the natural day through artificial lighting, rest at the hormonal level is rarely adequate for optimum biological needs of the body. In her view, this results in both fatigue and unnatural appetite, which leads to weight gain, exhaustion, and disease. Wiley theorizes that the body’s responses are cyclical, reflecting the seasons of the year, and that the body’s needs vary seasonally. According to Wiley, during the winter months the body needs more sleep, and carbohydrates should be restricted as they would have been naturally during hunter-gatherer times.”

melatonin

Most of the first third of Wiley’s book “Lights Out: Sleep, Sugar, and Survival” centers around light exposure, melatonin, and the many, many effects of a screwed up circadian cycle.  Jane Plain and Jack Kruse have written volumes on the subject, please see their websites for more in-depth analyses and practical applications…

Much of this blog post is my take on that first third (I couldn’t wait to finish it before writing about it), plus a little input from Google, Pubmed, et al; some commentary & pseudo-fact-checking as well.  I’m going to finish the book, and hopefully it will inspire a few more blog posts as opposed to a tin foil hat.  Most of the stuff in Lights Out makes incredibly good sense, but: 1) that doesn’t mean it’s true; and 2) the strings of logic are far too long to do a proper fact-check.  But really it’s how well it makes sense (mostly) that has me intrigued.

divide and conquer

Melatonin is a sleep-inducing hormone controlled by the light-dark cycle.  It is known.  On the day-to-day, melatonin increases at night and decreases during the daytime.  From Wiley: on a seasonal level, longer days during the summer meant less melatonin overall during these months.  Since melatonin suppresses sex hormones (inconsistent? Eg, Smith et al., 2013), summer is supposed to be breeding time, so the baby is born in spring when food is plenty (I’m OK with this now, but will certainly disagree come December).  Melatonin also suppresses metabolic rate, so the decreased daylight and thus increased melatonin during the winter months helped to survive on less food (supported by Marrin et al., 2013).

Disruptions in circadian rhythms royally screws us up.  According to Wikipedia, fireplaces/candles and incandescent bulbs produce less of the melatonin-suppressive blue lights… use these at night in winter?


Antidepressant and circadian phase-shifting effects of light. (Lewy et al., 1987)
Abstract: Bright light can suppress nighttime melatonin production in humans, but ordinary indoor light does not have this effect. This finding suggested that bright light may have other chronobiologic effects in humans as well. Eight patients who regularly became depressed in the winter (as day length shortens) significantly improved after 1 week of exposure to bright light in the morning (but not after 1 week of bright light in the evening). The antidepressant response to morning light was accompanied by an advance (shift to an earlier time) in the onset of nighttime melatonin production. These results suggest that timing may be critical for the antidepressant effects of bright light.

Next:  Prolactin inhibits sex hormones, and melatonin stimulates prolactin (supported by Gill-Sharma 2009Campino et al., 2008).  Thus, less melatonin in summer means less prolactin = more sex & fertility.  She also says day sex is more likely to result in conception compared to night sex for this reason (couldn’t find a reference for or against this).

Dopamine inhibits prolactin, whereas TRH & melatonin stimulate it.  Melatonin also blunts ACTH-induced cortisol secretion (supported by Torres-Farfan 2003Campino 2008).  Winter = high melatonin, prolactin, and low cortisol & dopamine.  Summer = high dopamine & cortisol, and low melatonin & prolactin.  Prolactin is supposed to be high in winter, during pregnancy; low dopamine would support this.

Circadian rhythm

Dopamine is a summer hormone?  Lu et al. (2006) showed high dopaminergic activity was associated with light and wakefulness (ie, summertime).  However, Venero (2002) showed melatonin stimulated dopamine synthesis in specific brain regions, and Eisenberg (2010) showed increased dopamine synthesis in fall & winter relative to spring and summer.  Two  possible confounding factors come to mind: 1) Location, location, location!  Some of these discrepancies may be due to brain region-specific dopamine metabolism… actually, Lu is the only odd-man out, so perhaps dopamine is a winter hormone?  And 2) Wiley’s main premise is that we pwned the light… epigenetics and the like mean that we, including the people in those studies, have deeply screwed up light/dark summer/winter metabolic programs on an epigenetic level, so it’s possible those studies are riddles with artefacts.  However, Wiley also says that people get sick because they live in perpetual summer (lights on all the time = high dopamine), and Markianos (2013) showed elevated dopamine metabolites in overweight patients; in my experience these studies usually continuously enroll patients, year-round.


I’m really just blazing through abstracts here – this is why I call it “pseudo-fact-checking;” not to be confused with any degree of academic rigor.

To be continued… (no tin foil hats, I promise) (not yet at least)

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calories proper