Tag Archives: Paleo

Artificial light regulates fat mass: no bueno.

“despite not eating more or moving less”

We’ve seen this time and time again: LIGHT IS A DRUG.

 

above quote is extrapolated from this rodent study: “Prolonged daily light exposure increases body fat mass through attenuation of brown adipose tissue activity.”

 

Artificial light impacts nearly every biological system, and it doesn’t even take very much to have an appreciable effect (think: checking your smart phone or watching a television show on your iPad in bed at night).  In this study, adding 4 hours to the usual 12 hours of light slammed the autonomic nervous system, disrupting sympathetic input into brown adipose leading to a significant increase in body fat  “despite not eating more or moving less.”

 

Continue reading

Share

Meal timing and peripheral circadian clocks

More on why breakfast in the morning, with light onset is important to avoid circadian desynchrony.

FOOD is excellent at entraining peripheral circadian clocks: if you restrict animals to one meal per day, their peripheral circadian clocks rapidly become entrained to this, regardless of when the meal is administered (Hirao et al., 2010):

 

zeitgeber entraining

ZT0 = “zeitgeber time 0,” or “lights on.” pZT indicates a phase shift coinciding almost exactly with meal timing. Mice normally eat at night, but this doesn’t stop their peripheral clocks from entraining to the day time if that’s when their fed.

This study took it to the next level: they fed 2 meals per day, varying in size, time of day, and duration between meals in almost every conceivable combination.  Actually, it was a quite epic study… some poor grad students working, literally, around the clock, for months…

Continue reading

Share

CICO and rant

“Wait… what?  nutrient partitioning?”

Calories In, Calories Out should not be interpreted as “eat less, move more,” but rather kept in its more meaningless form of: “if you eat less than you expend, you’ll lose weight.”  At least then, it’s correct… meaningless, but correct.  Eating less and moving more is no guarantee of fat loss, in part, because total energy expenditure isn’t constant and there’s that whole thing with nutrient partitioning.

For obese insulin resistant folks, this is Low Carb’s strong suit: it causes “eat less, move more”spontaneously.

For some obese insulin sensitive patients, for whatever reason, their adherence and success is greater with Low Fat.  You might say, “yeah, but those suckers had to count calories.”  To that, I’d counter with: “it doesn’t matter, THEY WERE MORE SUCCESSFUL COUNTING CALORIES ON LOW FAT THAN NOT COUNTING ON LOW CARB.”  The spontaneous reduction in appetite obviously didn’t cut it.  Do not be in denial of these cases.

Continue reading

Share

Ketosis in an evolutionary context

Humans are unique in their remarkable ability to enter ketosis.  They’re also situated near the top of the food chain.  Coincidence?

During starvation, humans rapidly enter ketosis; they do this better than king penguins, and bears don’t do it at all.

Starvation ketosis

 

Starvation ketosis

Humans maintain a high level of functionality during starvation.  We can still hunt & plan; some would even argue it’s a more finely tuned state, cognitively.  And that’s important, because if we became progressively weaker and slower, chances of acquiring food would rapidly decline.

Perhaps this is why fasting bears just sleep most of the time: no ketones = no bueno..?

Observation: chronic ketosis is relatively rare in nature.  Angelo Coppola interpreted that to mean animals may have evolved a protective mechanism against ketosis (if you were following along, please let me know if this is a misrepresentation).

Continue reading

Share

Paleo Plants and Carnivory

From what I gather, it’s been difficult to pinpoint the role of plants in the diet of our ancestors for a variety of reasons.  For example, evidence of plants on cooking tools and dental remains is suggestive but doesn’t disprove the possibility that said evidence came from preparing the plants for some other purpose (eg, tools, weapons, or medicine), or that the stomach contents of an herbivore was ingested (which gets partial credit).

That said, after reviewing a few studies on the topic (see below), it’s safe to say that plants were eaten, probably frequently, and the types & quantities varied seasonally & geographically.  Collectively, the data suggest we aren’t carnivores.

…you had to have something to hold you over until the next fish fell prey to your deadly hunting spear…  

Continue reading

Share

Lipid Hypothesis 2.0: Eat Butter

The original lipid hypothesis stated, more or less, that lowering blood cholesterol would reduce premature mortality from heart disease.  At the time, it was thought that dietary cholesterol and saturated fat increased the ‘bad’ type of blood cholesterol, so the advice was to restrict those foods.  All of that was wrong.

Time

Lipid Hypothesis 2.0: Eat Butter

Continue reading

Share

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).

Continue reading

Share

Fiat lux

Humans have a peculiar relationship with light: differences in brightness, wavelength, and even circadian timing all have biologically meaningful effects.

The right combination of timed light exposure and hot Blue Blockers is probably not only the solution to jet lag, but also to a whole host of other health problems.  Maybe you can’t completely escape the bane of the modern condition, but there are some tools, widely available, accessible, and even free in some cases (eg, sun), that may be of benefit.  

The frequency of light impacts circadian rhythms. 

Wright showed this in 2004.  The subjects wore special glasses with LEDs that emitted light of varying frequency for 2 hours, from 6 to 8 in the morning (65 uW/cm2).  Salivary melatonin measurements commenced at 7 pm.  As seen in the figure below, blue but not red light induced a significant phase advance in melatonin onset:

AM blue light phase advance

And for the whole group:all colors

Continue reading

Share

It’s paleo: Hypothyroidism impairs reproductive success in bitches.

Kisspeptin was discovered in Hershey, Pennsylvania, and was named after Hershey’s Kisses.  It has 776 pubmed citations going back to 2001, and may (or may not) play a key part integrating circannual reproduction patterns and seasonal thyroid function.

Kisspeptin was originally identified as a protein that inhibited breast cancer and melanoma.  This might also provide insight into the WHO’s recent declaration of shift work as a “probable” carcinogen.

Exhibit A. TSH restores a summer phenotype in photoinhibited mammals via the RF-amides RFRP3 and kisspeptin (Klosen 2013)

In this study, TSH infusion in short-day adapted hamsters (who are in winter non-breeding mode) induced summer phenotype & kisspeptin.  It also fattened them up a bit.  These TSH secreting neurons express melatonin receptors, but not those for TRH or T3 (Klosen 2002), so it is said to go something like this:Kisspeptin feedback diagram

Continue reading

Share

Paleo breeding: mating in the wild.

I’ve adapted much of this chart from Howell-Skalla (2002)  and Tsubota (1998).

Canadian polar bears: bona fide seasonal breeders.circannual hormones

The light cycle increases until June, then decreases until December.  Melatonin goes in the exact opposite direction. Testosterone peaks around the onset of breeding season (springtime, April/May), coinciding with LH (as expected). There is also a lot of bear-on-bear violence at this time due to: 1) testosterone-induced aggression; and 2) the high female:male ratio –-> females rear their cubs and are thus out of the game for about 3 years, but males like to breed every year.

Females followed a similar pattern, with estrogen peaking around breeding season and prolactin following the light cycle.

The authors mentioned that prolactin levels mirrored day length, and according to Wiley this would be the prolactin peak that normally occurs when you’re sleeping, but has spilled over into the daytime due to short sleep / long light cycle… not total prolactin levels (24h AUC?), which should be highest in winter (see below).

Continue reading

Share