Monday, August 31, 2009

Ghrelin and entrainment

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"New" research on ghrelin

Apparently, scientists have now discovered ghrelin's role in meal initiation and it's entrainment to habitual meal patterns. Funny, because I've been talking about this since I started the blog. Judging from the quick look through my collection of ghrelin related research papers, it seems the earliest paper mentioning this effect of ghrelin in humans is from 2001. The entrainment of ghrelin is part of what makes the 16 hour fast so easy after a few days adaptation.

Though it's not mentioned in the link, ghrelin has other interesting effects as well, such as stimulating brain functions of spatial learning and memory development. From an evolutionary perspective this makes sense; the urge to find food may create more competitive skills to ensure survival.

In a similar vein, the metabolic increase (via incrased norepinephrine/epinephrine) that occurs during short term fasting is a function of the body telling you to not sit on your ass, but go out and find food - another mechanism selected for during evolution. Yes, you read that right, "starvation mode" is a bunch of hokum, unless we're talking long term fasting (>72 hrs).

Either way, the link might be worth a read if you're not familiar with ghrelin. Will at least provide you with some backup material when people ask you why you aren't starving during the fast.

And when someone asks you why they're constantly hungry on their six meal-a-day-foo-foo-meal-regimen, you can refer them to dr Silver -

"If you eat all the time, ghrelin secretion will not be well controlled,” said Silver, the paper’s lead author and the principal investigator of the study."

14 comments:

Dor said...

What does "not well controlled" mean? What happens?

You have a mistake here -
"Though it's not mentioned in the link, ghrelin have other interesting effects as well... "

should be "ghrelin has".

Cheers

UofMWolverine81 said...

Martin,

I think your approach to fasting is a fantastic one, so this isn't meant to come across as contrary or argumentative. I'm just curious where you see the role of self-discipline fitting in with meal frequency.

Namely, if you have someone who eats moderate amounts at a greater frequency but demonstrates no issues with controlling intake and feels satisfied, would you take any issue with that approach?

Or is it more a case of finding what fits you and your lifestyle and not being a "slave" to dogma when deciding on what approach to take? e.g. if many "mini" meals leaves you hungering for more, then don't stick to it just because it's a common meme, but on the flip side, if it does work for you, don't feel compelled to switch to an IF approach despite the fact that you've highlighted a host of evidence-based reasons why it can be so effective?

Thanks for sharing all of your knowledge. I am grateful each and every time I get the opportunity to come to your site and check out all that you share.

Martin Berkhan said...

Dor -

'What does "not well controlled" mean? What happens?'

I think dr Silver is referring to another study which showed some curious effects of a high meal frequency with regards to the insulin:glucagon ratio and ghrelin. I recall it, and probably have it saved somewhere, but can't remember the specifics. I'd have to look through the full text version of dr Silvers paper to see what she was trying to say (assuming she brings elaborates further). I'm pretty sure nothing bad would happen, other than that it may mess with appetite regulation.

Thanks for pointing out the error, I appreciate it. I hate poor grammar.

Wolverine-

'Namely, if you have someone who eats moderate amounts at a greater frequency but demonstrates no issues with controlling intake and feels satisfied, would you take any issue with that approach? '

This question baffles me. If you've been reading my blog for any amount of time, you'd know that I'm not a fanatic.

This -

'Or is it more a case of finding what fits you and your lifestyle and not being a "slave" to dogma when deciding on what approach to take?'

Is what I ultimately care about.

'I am grateful each and every time I get the opportunity to come to your site and check out all that you share.'

Thanks for the kind words. Glad you like the blog and my writings.

Anonymous said...

I find your attitude refreshing. Other blogs on somewhat niche health/fitness topics always have unfounded biases. Low carb that, paleo this etc. Often loaded with holistic bullcrap. Contrary to them yours is very readable, balanced and provide evidence based information. I like it. Keep up the great work.

Sterling said...

Martin - As always, your comments are to the point and leave no room for BS. I think everyone who reads your blog, greatly appreciates your approach; not to mention, that your no-nonsense approach freaking works!

Miguel Angel said...

All i can say, IF ROCKS! im doing a PSMF with the Martin protocol of 16/8 and its incredibly more easier than the 3-6 meals per day because i tried the PSMF before with that aproach and i was all the day hungry, but now im not hungry at all!
Obviously i dont have too much energy because of the low calorie of the PSMF but i have maintained the muscle mass perfectly while im loosing fat really fast.

Wazzup said...

That ties in exactly with my own experience... lot's of small meals = hungry all the time (even when hypercaloric) Eating larger meals in a shorter time frame (aka IF) = no hunger at all (well a bit peckish at the end of the fast) even when hypocaloric.

hoyt said...

same here...bulking with 5-6 smaller meals almost feels like dieting for me...constant cravings...not so with martin's approach. just pissed i didn't discover if and this blog sooner...wasted so much time with the whoele eat like a bodybuilder mindset. never got lean for summer until i used if and im never going to go back to my old eating habits

hoyt

Anonymous said...

Great blog. Keep up the good work. A thought though... has there been any research done on carbs vs protein and ghrelin? Do they both "up" the ghrelin equally?

Why I ask is because I feel much more fuller (and for a much longer time) when on a high protein/low carb diet. Has this anything to do with ghrelin?

Martin Berkhan said...

'A thought though... has there been any research done on carbs vs protein and ghrelin? Do they both "up" the ghrelin equally?'


The rank order for magnitude of suppression is protein -> carbs -> fat. This is when looking at the net effect, i.e measured over a longer time period. When measured in the short term, <3 hrs or so, carbs have the strongest suppressive effect, but later on rebounds at the 5-6 hr mark. Protein and fat are more consistent, i.e they show a longer lasting suppressive effect, which might be part of the reason why low carb diets anecdotally keeps hunger more stable and non-fluctuating.

VegardGoogleGroups said...

Thanks Martin Berkhan. You might be a bit VERY direct at times.

But, you're right. You have tested out this fitness game, and you adress the rightq questions. It's a matter of seeing the bridge between theory and real life.

God bless you for this blog.

Keep up the work! PUBLISH THE BOOK :)

Bill Medifast said...

Thanks Mark for this. I know many people just don't understand how to take it or even do what you do. Thanks for sharing this. I agree with the above commenter, publish the book!

Anonymous said...

I am reading this article second time today, you have to be more careful with content leakers. If I will fount it again I will send you a link

Anonymous said...

Do you have copy writer for so good articles? If so please give me contacts, because this really rocks! :)




My name is Martin Berkhan and I work as a nutritional consultant, magazine writer and personal trainer.

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