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MikeK46
02-06-2011, 07:57 PM
Leptin is often touted as a hormone that controls appetite and energy expenditure. When dieting for long periods of time, refeeds (and I do not mean carb-ups) are advocated to prevent downregulation of metabolic rate and reduce hunger. They advocate increasing carbs significantly by dropping fat to 10-20% and increasing total calories 50-100% (with the excess calories all coming from carbs).

However, Lyle McDonald notes that refeeds wonít do much for dieters in terms of leptin because leptin kicks up and down very rapidly as energy intake fluctuates. Therefore, while leptin may kick up with a 10-hour carbohydrate reefed, itís likely to drop back down just as rapidly after the reefed is over and another 10 hours of dieting are accomplished.

On top of that, when I tried to find out how exactly leptin can raise metabolic rate, all I found was that it couldn't. So apparently there's not much reason to refeed except for a psychological break from dieting, better glycogen status, and more intense workouts. Thoughts? I've been re-feeding every Saturday thinking I was doing my metabolism a favor. Have I been wasting a day per week eating above maintenance when I could've been burning fat?

"Increasing evidence from human studies suggests that leptin predominantly influences the human energy balance through appetite but appears not to be involved in regulating energy expenditure. None of the expected factors such as resting metabolic rate, total diurnal energy expenditure or dietary induced thermogenesis was related to blood leptin concentrations."

http://www.ncbi.nlm.nih.gov/pubmed/15534430

"After adjusting for body composition (fat-free mass and fat mass), gender, and ethnicity, serum leptin concentrations were not related to any measure of energy expenditure."

http://jcem.endojournals.org/cgi/content/abstract/82/12/4149

vitriol
02-06-2011, 08:16 PM
very interesting read..

goodnight sweet cheatmeals :(

SwiftyX
02-06-2011, 08:39 PM
There's also that refeeds allow a temporary break from diet induced catabolism. Which becomes very important the leaner you get. Aside from that any regulation even small amounts to leptin,ghrelin, insulin, and peptide YY is going to help. If you want upregulation of all hormones a diet break is what you are looking for, which should also be scheduled in more frequently the leaner you are.

Ransom17
02-06-2011, 08:50 PM
Have you guys been using cheat meals as a metabolic boost? Geez, I thought they were just some psychological relief.

almightyares
02-06-2011, 08:52 PM
I thought refeeds are for appetite suppression, to fill glycogen, and to prevent the further decrease in metabolism from a daily calorie deficit? I didnt even know it was supposed to raise the metabolism, other than the feeding aspect of it.

How is a refeed supposed to increase leptin anyways...AFAIK the bodies fat cells produce leptin, not a carb feed. Even if a refeed increased leptin, I would think the leptin blood levels would decrease just as fast as they increased (which doesnt seem like it would give much benefit in this aspect) after digestion.

bfactor
02-06-2011, 08:53 PM
Those are pretty old papers. The second one was a 1997 study on prepubescent children. Some of the same authors of the first paper published another in 2007 that demonstrated increased weight loss for VLCD dieters when injected with leptin.

Physiol Behav. 2007 Mar 15
"Effects of very low calorie diet induced body weight loss with or without human pegylated recombinant leptin treatment on changes in ghrelin and adiponectin concentrations."

greekmanman
02-06-2011, 08:53 PM
There's also that refeeds allow a temporary break from diet induced catabolism. Which becomes very important the leaner you get. Aside from that any regulation even small amounts to leptin,ghrelin, insulin, and peptide YY is going to help. If you want upregulation of all hormones a diet break is what you are looking for, which should also be scheduled in more frequently the leaner you are.

This, plain and simple.

desslok
02-06-2011, 10:00 PM
Scammed? How much money have you spent on leptin?

MikeK46
02-07-2011, 07:20 AM
Scammed? How much money have you spent on leptin?

Well, if you include the pretzels and bagels....it adds up!

In all seriousness, I would at least hope that a refeed to maintenance or above (even for 1 day) would increase or prevent decrease in other metabolic hormones such as T3.

Gusthebus
02-07-2011, 07:35 AM
Interesting topic. Would like to know more about refeeds as well.

mynameisuntz
03-08-2011, 01:01 AM
Cool, bumping this.

So what is the role of leptin, then? I know Lyle has a multiple-part series talking about it, and I felt certain that leptin promoted fat oxidation (when at optimal levels). I think it was Lyle who said, "You lost fat by raising calories. Because of magic and voodoo. Or leptin. One of those." I think I saw that in his forums or an article somewhere.

So based on what you're saying here, what is the role of leptin exactly? Does it work to regulate hunger/satiety?

Trillios
03-08-2011, 01:40 AM
I gave up on the idea of leptin being affected a month ago and tracked total cals/protein instead of specific macros (like i have traditionally for the past 2 yrs or so) and anecdotally speaking I'm looking and feeling much better. I'm not holding back on dietary fat on refeed days (but either way I predominantly choose carbs over fats lol).

My personal opinion is the "low" people feel is more glycogen depletion than a "metabolic slow-down". It just makes more sense in my head especially since after you refeed your workout intensity is ridiculous.

mynameisuntz
03-08-2011, 11:08 AM
Cool, bumping this.

So what is the role of leptin, then? I know Lyle has a multiple-part series talking about it, and I felt certain that leptin promoted fat oxidation (when at optimal levels). I think it was Lyle who said, "You lost fat by raising calories. Because of magic and voodoo. Or leptin. One of those." I think I saw that in his forums or an article somewhere.

So based on what you're saying here, what is the role of leptin exactly? Does it work to regulate hunger/satiety?

Bumping for this :D

JohnBrowne
03-08-2011, 11:12 AM
Bumping for this :D

Leptin primarily controls appetite.

To put it simply: leptin (and ghrelin etc) controls intake, T3 and other thyroid hormones control expenditure.

It's much more complicated than that... but that gives you a basic understanding.

kingof_queens
03-08-2011, 11:24 AM
I'm going to pretend I never read this thread or the article.

Ignorance is bliss baby. :)

angryguywalking
03-08-2011, 11:27 AM
I agree with the OP 100%

JOSEF RAKICH
03-08-2011, 11:33 AM
Interesting..

Awaiting more info.

mynameisuntz
03-08-2011, 11:37 AM
Leptin primarily controls appetite.

To put it simply: leptin (and ghrelin etc) controls intake, T3 and other thyroid hormones control expenditure.

It's much more complicated than that... but that gives you a basic understanding.

Would you say Lyle was simply mistaken in what I quoted from him earlier? ("You lost fat by raising calories. Because of magic and voodoo. Or leptin. One of those.") Or am I misunderstanding the intent of that quote?

And if I'm not mistaken, a refeed to benefit thyroid hormone(s) takes 1-2 weeks of eating at maintenance (or slightly above maintenance)? Is that correct?

Newbiewar
03-08-2011, 11:39 AM
I was reading Lyle's blog on leptin, and it had stated that Leptin is basically non-existent for people with under 10% bodyfat.

http://www.bodyrecomposition.com/fat-loss/the-hormones-of-bodyweight-regulation-leptin-part-the-last.html

"Leptin production in the fat cell
I talked a little bit about #1 in a previous post, when I talked about refeeds. At this point, and this topic is discussed to some degree in nearly every book Iíve written at this point, interjecting high carbohydrate, high calorie refeeds of varying lengths (anywhere from 5 hours to 3 days) is (currently) the best way to raise leptin while dieting.
One of the interesting (and often missed points) is that, as dieters get leaner (and leptin drops more and more), refeeds need to become larger and/or more frequent. That is, rather than necessarily dieting harder as they get leaner, some people are actually doing better by Ďbreaking their dietí (with specific high-carb refeeds) more frequently.
Iíd note again that leptin production is related primarily to carbohydrate intake in the short-term, high-fat refeeds arenít the best way to raise leptin levels. Iíd also note that single Ďcheatí meals wonít impact on leptin levels significantly as leptin doesnít really change on a meal to meal basis.
Tangent: Iíd note that, in this regards, some of the work being done with intermittent fasting and every other day refeeds has relevance here as some data suggests that leptin may be maintained better with that approach to dieting. But until I get Martin Berkhan in here from LeanGains for an interview and dig into it more, Iím not going to talk much about IFíing as a dietary strategy other than to say: thereís some compelling **** going on here.
An additional strategy, talked about in some detail in my Guide to Flexible Dieting is the idea of full diet breaks, periods of 10-14 days in-between periods of active dieting where calories are brought back to maintenance (and carb intakes brought back to at least moderate levels).
Not only does this provide a psychological break from the grind of continuous dieting, it helps to Ďresetí some of the metabolic adaptations that occur with dieting. Leptin levels will come up, thyroid conversion in the liver is improved, etc. Assuming dieters have no strict time constraints, I strongly feel that inserting full diet breaks every so often (how often depends on body fat levels) is important for long-term success. Again, for both physiological and psychological reasons."

Dexter3000
03-08-2011, 11:41 AM
http://www.leangains.com/2010/03/intermittent-fasting-set-point-and.html

mynameisuntz
03-08-2011, 03:19 PM
Would you say Lyle was simply mistaken in what I quoted from him earlier? ("You lost fat by raising calories. Because of magic and voodoo. Or leptin. One of those.") Or am I misunderstanding the intent of that quote?

And if I'm not mistaken, a refeed to benefit thyroid hormone(s) takes 1-2 weeks of eating at maintenance (or slightly above maintenance)? Is that correct?

Bump.

DDon1996
03-08-2011, 03:29 PM
Leptin is often touted as a hormone that controls appetite and energy expenditure. When dieting for long periods of time, refeeds (and I do not mean carb-ups) are advocated to prevent downregulation of metabolic rate and reduce hunger. They advocate increasing carbs significantly by dropping fat to 10-20% and increasing total calories 50-100% (with the excess calories all coming from carbs).

However, Lyle McDonald notes that refeeds won’t do much for dieters in terms of leptin because leptin kicks up and down very rapidly as energy intake fluctuates. Therefore, while leptin may kick up with a 10-hour carbohydrate reefed, it’s likely to drop back down just as rapidly after the reefed is over and another 10 hours of dieting are accomplished.

On top of that, when I tried to find out how exactly leptin can raise metabolic rate, all I found was that it couldn't. So apparently there's not much reason to refeed except for a psychological break from dieting, better glycogen status, and more intense workouts. Thoughts? I've been re-feeding every Saturday thinking I was doing my metabolism a favor. Have I been wasting a day per week eating above maintenance when I could've been burning fat?

"Increasing evidence from human studies suggests that leptin predominantly influences the human energy balance through appetite but appears not to be involved in regulating energy expenditure. None of the expected factors such as resting metabolic rate, total diurnal energy expenditure or dietary induced thermogenesis was related to blood leptin concentrations."

http://www.ncbi.nlm.nih.gov/pubmed/15534430

"After adjusting for body composition (fat-free mass and fat mass), gender, and ethnicity, serum leptin concentrations were not related to any measure of energy expenditure."

http://jcem.endojournals.org/cgi/content/abstract/82/12/4149

I haven't read the thread, so forgive me if this has been covered, but what if the drop in metabolism while on a caloric deficit isn't caused by leptin, but perhaps mediated by another pathway?

First thing that popped into my mind, anyway.

adean1989
03-08-2011, 03:47 PM
Mike you're right and wrong on this one. Leptin DOES by some very obscure misunderstood metabolic pathway regulate metabolism, we don't know yet how but for instance:

http://www.pnas.org/content/94/9/4242.full

On the other hand, since several leptin receptor isoforms are expressed in peripheral sites, direct effects on peripheral tissues could underlie some of leptin’s biological actions. This issue is addressed in the paper of Shimabukuro et al. (13) in this issue of the Proceedings. Using recombinant adenoviral vectors to create continuously high leptin levels in normal rats, these researchers previously reported severe depletion of adipose stores, far exceeding the consequences of restricted food intake alone (69). Because leptin has been shown in a preliminary report to activate nerve activity in highly thermogenic brown adipose tissue (70), it is not surprising that leptin-induced weight loss exceeded that from food restriction. Indeed, this was previously reported in mice receiving leptin injections (71). However, the lipid depletion they observed (69) was so extreme that it raised questions about the biochemical and physiologic mechanisms involved, and the current paper (13) raises two important points in this regard.

Science is in two minds about this one, Leptin's primary target is certainly the hypothalamus and regulating appetite, but at the same time the popular consensus is that it has a role in the bigger picture.

With regards to refeeds, yep they're pretty useless in terms of restoring metabolism/long term sanity, if anything the psychological break from diet + refilling of glycogen stores is incentive enough for those who can afford to do so!

DDon1996
03-08-2011, 03:53 PM
Mike you're right and wrong on this one. Leptin DOES by some very obscure misunderstood metabolic pathway regulate metabolism, we don't know yet how but for instance:

http://www.pnas.org/content/94/9/4242.full

On the other hand, since several leptin receptor isoforms are expressed in peripheral sites, direct effects on peripheral tissues could underlie some of leptinís biological actions. This issue is addressed in the paper of Shimabukuro et al. (13) in this issue of the Proceedings. Using recombinant adenoviral vectors to create continuously high leptin levels in normal rats, these researchers previously reported severe depletion of adipose stores, far exceeding the consequences of restricted food intake alone (69). Because leptin has been shown in a preliminary report to activate nerve activity in highly thermogenic brown adipose tissue (70), it is not surprising that leptin-induced weight loss exceeded that from food restriction. Indeed, this was previously reported in mice receiving leptin injections (71). However, the lipid depletion they observed (69) was so extreme that it raised questions about the biochemical and physiologic mechanisms involved, and the current paper (13) raises two important points in this regard.

Science is in two minds about this one, Leptin's primary target is certainly the hypothalamus and regulating appetite, but at the same time the popular consensus is that it has a role in the bigger picture.

With regards to refeeds, yep they're pretty useless in terms of restoring metabolism/long term sanity, if anything the psychological break from diet + refilling of glycogen stores is incentive enough for those who can afford to do so!

Rats are NOT humans.

WonderPug
03-08-2011, 03:57 PM
Rats are NOT humans.

True, but I've met lots of humans who were rats ;)

adean1989
03-08-2011, 04:34 PM
Rats are NOT humans.

So you're going to completely disregard all animal models? It's certainly a criticism, but with that train of thought we may as well give up on science because of the ethical constraints and inability to extrapolate findings.

mynameisuntz
03-08-2011, 04:38 PM
So you're going to completely disregard all animal models? It's certainly a criticism, but with that train of thought we may as well give up on science because of the ethical constraints and inability to extrapolate findings.

I know one of the main issues with rodent models is the metabolizing of CHO and how different it is from humans. I know leptin is [partially/entirely?] regulated by carbs, and so perhaps a rodent model may be lacking in this instance.

Anyone have an explanation as to why Lyle and the literature seem to differ so much?

DDon1996
03-08-2011, 04:39 PM
So you're going to completely disregard all animal models? It's certainly a criticism, but with that train of thought we may as well give up on science because of the ethical constraints and inability to extrapolate findings.

No- but I am definitely going to favor human studies as opposed to rat studies when both are at my disposal.

adean1989
03-08-2011, 04:41 PM
No- but I am definitely going to favor human studies as opposed to rat studies when both are at my disposal.

You're free to do this, but it would be wise to note that there's only so much we can do with humans and if everyone adopted this approach science would never move forward.

DDon1996
03-08-2011, 05:13 PM
You're free to do this, but it would be wise to note that there's only so much we can do with humans and if everyone adopted this approach science would never move forward.

Hmmm. Can you explain why you are favoring the rat research over the human research, even though the human research has consistently shown the same results to be accurate? Especially in a topic such as this, which, as untz mentioned, has a MASSIVE documented and universally accepted difference between rat and human subjects?

Cumulonimbus
03-08-2011, 05:27 PM
Rats are NOT humans.

No clue how you're 14.. dammit you impress me more each day.

DDon1996
03-08-2011, 05:29 PM
No clue how you're 14.. dammit you impress me more each day.

Thank you, Clomubanus dude.

JohnBrowne
03-08-2011, 05:36 PM
You're free to do this, but it would be wise to note that there's only so much we can do with humans and if everyone adopted this approach science would never move forward.

Leptin functions very differently in humans than in rats and this is heavily documented in the relevant research.

adean1989
03-08-2011, 05:50 PM
Hmmm. Can you explain why you are favoring the rat research over the human research, even though the human research has consistently shown the same results to be accurate? Especially in a topic such as this, which, as untz mentioned, has a MASSIVE documented and universally accepted difference between rat and human subjects?

I'm not favouring rat research, and I agree Leptin has well documented differences between rats and humans. Never the less, we can't manipulate humans how we do with rodents. Were we to keep Leptin levels abnormally high for a prolonged period of time akin to the mentioned study, maybe we'd see results, maybe we wouldn't. But you're being very close-minded, there's very few universal truths in science.

DDon1996
03-08-2011, 05:59 PM
I'm not favouring rat research, and I agree Leptin has well documented differences between rats and humans. Never the less, we can't manipulate humans how we do with rodents. Were we to keep Leptin levels abnormally high for a prolonged period of time akin to the mentioned study, maybe we'd see results, maybe we wouldn't. But you're being very close-minded, there's very few universal truths in science.

Close-minded? I disagree. I'm being a realist. Above all, I try to refrain from being close-minded, which is why I asked for you to elaborate on your side of the discussion.

You came into the thread with a very strong opinion on the subject, "Leptin DOES... regulate metabolism."

I was simply trying to get some clarification and perhaps further my knowledge on the matter.

Number_Seven
03-08-2011, 06:12 PM
in for tomorrow, damn English homework getting in the way of learning.

YeomenKek
03-08-2011, 06:16 PM
Always surprises me how quickly people are able to shoot down animal studies considering the amount of diseases treatable today due to testing on animals (diabetes, anyone?). I'm of course speaking in general, not the specific case in this thread.

Also, I regret opening this thread as planning my refeeds is probably one of the most exciting times of the week for me apart from actually doing them. A lot of my general happiness and well-being revolves around my refeeds and the [previous] assumption it has a positive effect on my long-term goal(s) lol.

adean1989
03-08-2011, 06:22 PM
Close-minded? I disagree. I'm being a realist. Above all, I try to refrain from being close-minded, which is why I asked for you to elaborate on your side of the discussion.

You came into the thread with a very strong opinion on the subject, "Leptin DOES... regulate metabolism."

I was simply trying to get some clarification and perhaps further my knowledge on the matter.

This is clearly a misunderstanding, and quoting a small portion of my original post makes me look far more bias:


Mike you're right and wrong on this one. Leptin DOES by some very obscure misunderstood metabolic pathway regulate metabolism, we don't know yet how but for instance:

I acknowledge that there's no solid evidence, excuse the emphasis by capitalizing "does", but of the literature I've read (can't quote it all off the top of my head) and with all due consideration to the differences between rats and humans, I'm siding with the scientific consensus of there is an influence, remember science is also opinion? ;)

Ghosting
03-08-2011, 06:24 PM
Thank you, Clomubanus dude.

Ohsnap.jpg lol

How can you possibly be 14 and be so smart?

angryguywalking
03-08-2011, 06:25 PM
This is clearly a misunderstanding, and quoting a small portion of my original post makes me look far more bias:



I acknowledge that there's no solid evidence, excuse the emphasis by capitalizing "does", but of the literature I've read (can't quote it all off the top of my head) and with all due consideration to the differences between rats and humans, I'm siding with the scientific consensus of there is an influence, remember science is also opinion? ;)

There's just not enough adequate studies for it to properly decide if a person is wrong or not. He was just trying to get a more in depth opinion, but nobody's saying you're wrong either.

DDon1996
03-08-2011, 06:26 PM
This is clearly a misunderstanding, and quoting a small portion of my original post makes me look far more bias:



I acknowledge that there's no solid evidence, excuse the emphasis by capitalizing "does", but of the literature I've read (can't quote it all off the top of my head) and with all due consideration to the differences between rats and humans, I'm siding with the scientific consensus of there is an influence, remember science is also opinion? ;)

Ah, in that case, opinions will differ. I was just wondering if (and hoping) you knew something that I didn't. :p

Ohsnap.jpg lol

How can you possibly be 14 and be so smart?

Idunnolol. This is all I do in my free time...




Except when I do other stuff.

Ghosting
03-08-2011, 06:30 PM
Idunnolol. This is all I do in my free time...




Except when I do other stuff.

Buahahhahahahahahhaa!!

adean1989
03-08-2011, 06:31 PM
Ah, in that case, opinions will differ. I was just wondering if (and hoping) you knew something that I didn't. :p


Idunnolol. This is all I do in my free time...




Except when I do other stuff.

Nothing like a little healthy scientific debate :P I'm more impressed with how mature he is than how smart. Baffling -_-

DDon1996
03-08-2011, 06:34 PM
Nothing like a little healthy scientific debate :P I'm more impressed with how mature he is than how smart. Baffling -_-

Debating/discussing is definitely a much more fun way to obtain new knowledge than hours of research!

Thanks, there IS hope for my generation! :)

SeanRector
03-08-2011, 07:30 PM
Lol i was having a refeed today and then i see this.

Quelly
03-08-2011, 07:38 PM
The vast majority of studies on leptin examines overweight populations...that's because we as a society are concerned with obesity from a medical standpoint...BUT you guys need to look at the studies on lean individuals....

sure the folks on biggest loser don't need refeeds and leptin won't drop below a certain point enough to slow down met rate....but getting below like 20% bodyfat....leptin becomes increasingly more important the leaner you get

http://www.bodyrecomposition.com/fat-loss/too-much-cardio-followup.html#more-5867

JohnBrowne
03-08-2011, 08:00 PM
The vast majority of studies on leptin examines overweight populations...that's because we as a society are concerned with obesity from a medical standpoint...BUT you guys need to look at the studies on lean individuals....

sure the folks on biggest loser don't need refeeds and leptin won't drop below a certain point enough to slow down met rate....but getting below like 20% bodyfat....it becomes increasingly more important the leaner you get

http://www.bodyrecomposition.com/fat-loss/too-much-cardio-followup.html#more-5867

What point are you trying to make exactly?

Quelly
03-08-2011, 08:01 PM
What point are you trying to make exactly?

dont stop refeeding

JohnBrowne
03-08-2011, 08:03 PM
dont stop refeeding

True; there are good reasons to refeed but leptin manipulation isn't one of them.

Quelly
03-08-2011, 08:09 PM
True; there are good reasons to refeed but leptin manipulation isn't one of them.

mechanism could be debated....however it can be stated unequivocally that increased carbohydrate intake increases leptin, and that short term overfeeding of carbohydrate also increases energy expenditure

Quelly
03-08-2011, 08:24 PM
a better conclusion of that 2004 review that is causing all this fuss would be "leptin does not have an effect on energy expenditure in the overweight populations we reviewed"

other studies show that leptin, overfeeding (specifically carbs, but also total intake), and energy expenditure are all directly related

http://www.ncbi.nlm.nih.gov/pubmed/11994393?dopt=Abstract

http://www.ncbi.nlm.nih.gov/pubmed/16322796?dopt=Abstract

http://www.ncbi.nlm.nih.gov/pubmed/11126336?dopt=Abstract

http://www.ncbi.nlm.nih.gov/pubmed/10479193?dopt=Abstract

In "lean" folks (below setpoint), leptin manipulation does matter, and does cause an increase in energy expenditure

JohnBrowne
03-08-2011, 08:30 PM
That's all practically irrelevant because as soon as you go back to a lower carb intake leptin will drop again almost immediately.

DDon1996
03-08-2011, 08:37 PM
a better conclusion of that 2004 review that is causing all this fuss would be "leptin does not have an effect on energy expenditure in the overweight populations we reviewed"

other studies show that leptin, overfeeding (specifically carbs, but also total intake), and energy expenditure are all directly related

http://www.ncbi.nlm.nih.gov/pubmed/11994393?dopt=Abstract

http://www.ncbi.nlm.nih.gov/pubmed/16322796?dopt=Abstract

http://www.ncbi.nlm.nih.gov/pubmed/11126336?dopt=Abstract

http://www.ncbi.nlm.nih.gov/pubmed/10479193?dopt=Abstract

In "lean" folks (below setpoint), leptin manipulation does matter, and does cause an increase in energy expenditure

The first two are definitely interesting- although not convincing (n=7 non-obese, assuming the first study was done on non-obese subjects, between them). I would like for someone with access to the full articles (Alan, perhaps?) to review them and give his opinion on the matter.

alan aragon
03-08-2011, 08:42 PM
Always surprises me how quickly people are able to shoot down animal studies considering the amount of diseases treatable today due to testing on animals (diabetes, anyone?). I'm of course speaking in general, not the specific case in this thread.Guess where drug testing must progress to after it passes the pre-clinical phase with animals.

DDon1996
03-08-2011, 08:44 PM
Guess where drug testing must progresses to after it passes the pre-clinical phase with animals.

A whole 5 minutes to reply after being called upon? Getting slow in your old age!

Seriously though, how the hell do you pop up in a thread randomly 5 minutes after being mentioned? Nice spidey sense.

MikeK46
03-08-2011, 09:00 PM
I haven't read the thread, so forgive me if this has been covered, but what if the drop in metabolism while on a caloric deficit isn't caused by leptin, but perhaps mediated by another pathway?

It's not and no one ever claimed it was. The downregulation of metabolism is caused by a drop in thyroid hormones. The drop in leptin is not the cause, it's the effect.


Mike you're right and wrong on this one. Leptin DOES by some very obscure misunderstood metabolic pathway regulate metabolism, we don't know yet how but for instance....

It would be nice if it did regulate metabolic rate, but as of now there's still nothing that proves it. PRO metabolism in rats may be similar to that in humans, but like "mynameisuntz" said, CHO metabolism is different, so rats aren't the ideal animals to be making any conclusions from on this.

Everything that makes rats lean doesn't do anything in humans. When it comes to energy expenditure, the physiology is way too different, but of course you'll still have the rat studies because you can have 100% control over them and they have a short life span.
-Lyle McDonald

"Unfortunately, what works in mice, doesnít always work in humans. It has since been found that when leptin levels are reduced by 80% in humans there is no change in resting metabolic rate." [Chan JL, 2007]

"When Leptin is injected into fasting individuals it doesnít improve fat burning or decrease GH levels." [Chan JL, 2008]

Research has shown consistently that there are substantial differences in the physiological actions of leptin between rodents and humans and this may explain why there is so much leptin-confusion in the diet industry. So "although it is widely known that leptin acts on hypothalamic neuronal targets to regulate energy balance and neuroendocrine function, the specific neuronal populations mediating leptin action on feeding behavior and autonomic and neuroendocrine function are not well understood." [Ahima RS, 2000]


With regards to refeeds, yep they're pretty useless in terms of restoring metabolism/long term sanity, if anything the psychological break from diet + refilling of glycogen stores is incentive enough for those who can afford to do so!

Like JohnBrowne said, there are still good reasons to refeed besides leptin levels, and I'm talking physiological, not psychological. Besides the mental break of dieting, refeeding can replenish/supercompensate glycogen stores, reduce cortisol, increase testosterone, and increase T4 to T3 conversion, TSH, and TRH. The last four are thyroid hormones which are known to have a direct effect on metabolic rate.

DDon1996
03-08-2011, 09:08 PM
It's not and no one ever claimed it was. The downregulation of metabolism is caused by a drop in thyroid hormones. The drop in leptin is not the cause, it's the effect.




Oh. I thought that was the point of this thread, lol. What were you getting at in the OP in relation to leptin, then? :confused:

mynameisuntz
03-08-2011, 09:12 PM
Like JohnBrowne said, there are still good reasons to refeed besides leptin levels, and I'm talking physiological, not psychological. Besides the mental break of dieting, refeeding can replenish/supercompensate glycogen stores, reduce cortisol, increase testosterone, and increase T4 to T3 conversion, TSH, and TRH. The last four are thyroid hormones which are known to have a direct effect on metabolic rate.

How long of a refeed are we talking here? One day per week like it is suggested for the "leptin-based" refeeds (for people who are on the leaner side)? Or a longer period of time in order to 'reset' the previously mentioned hormones?

YeomenKek
03-08-2011, 09:30 PM
Guess where drug testing must progress to after it passes the pre-clinical phase with animals.

Is it... oomans?

MikeK46
03-08-2011, 09:34 PM
Oh. I thought that was the point of this thread, lol. What were you getting at in the OP in relation to leptin, then? :confused:

The point I was getting at was that upregulating leptin is not a valid reason for a refeed.


How long of a refeed are we talking here? One day per week like it is suggested for the "leptin-based" refeeds (for people who are on the leaner side)? Or a longer period of time in order to 'reset' the previously mentioned hormones?

The longer the refeed the closer you'll be bringing hormone levels back to normal. A week at maintenance is going to be more beneficial than one refeed day of slightly above maintenance.

AlwaysTryin
03-08-2011, 09:38 PM
The point I was getting at was that upregulating leptin is not a valid reason for a refeed.


Good interview with John Beradi mentioned that


Lyle McDonald (more of a leptin expert than Iíll ever be) and I just had a discussion about this with David Greenwalt and his coaching group over at leannesslifestyle.com and we both pretty much concluded that refeeds probably wonít do much for dieters in terms of leptin. For starters, leptin kicks up and down very rapidly as energy intake fluctuates. Therefore, while leptin may kick up with a 10-hour carbohydrate reefed, itís likely to drop back down just as rapidly after the reefed is over and another 10 hours of dieting are accomplished. Therefore, a dieter may just end up with a bigger positive energy balance during those 24hours of refeeding and subsequent return to dieting.

Since there is no data, one way or the other, illustrating what happens in dieting weight lifters when refeeding, there's only speculation. Of course, leptin itself aside, if there were some prolonged increase in leptin, we should be able to measure the effects of this leptin increase by observing increases in metabolic rate the day after the refeed. Unfortunately, metabolic increases as a result of acute overfeeding arenít observed a day after the overfeed (or refeed). Remember, weíre not so much interested in whatís happening with leptin itself but whatís happening to metabolism. Leptin doesnít impact fat loss. The effects of leptin do. And it doesnít appear that refeeds impact metabolism for any longer than the day of the refeed.

However, make no mistake about it. I am not saying that refeeds are useless. In fact, I do see other good reasons (i.e. a psychological break from dieting, increased adherence, better glycogen status, more intense workouts, suppression of the catabolic hormonal cascade associated with dieting) for refeeding besides the leptin issue. A common strategy that I use with dieting bodybuilders is to have them do a 1-day refeed once per week. This refeed usually contains 50% - 100% more energy than their daily intake from the other 6 days. Therefore if the bodybuilder is eating 1000 kcal per day, he/she will refeed on 1500 Ė 2000 kcal. Likewise, if the bodybuilder is eating 2000 kcal per day, he/she will refeed on 3000 Ė 4000 kcal. The magnitude of the re-feed is dependent on their leanness, on how low their energy intake is, and on their rate of fat loss.

DDon1996
03-08-2011, 09:38 PM
The point I was getting at was that upregulating leptin is not a valid reason for a refeed.




Because of it's lack of effect on metabolism, correct? That's what I was saying- refeeds are still viable because the downregulation is mediated by a pathway unrelated to leptin.

Is ^^ true?

You aren't specifically disregarding refeeds- but rather arguing against leptin being the driving factor, yeah?

t1ger
03-08-2011, 09:49 PM
Because of it's lack of effect on metabolism, correct? That's what I was saying- refeeds are still viable because the downregulation is mediated by a pathway unrelated to leptin.

Is ^^ true?
Well, a range of anabolic hormones are elevated which get lowered when dieting apart from leptin. So yeah? :p

Trillios
03-08-2011, 09:55 PM
The point I was getting at was that upregulating leptin is not a valid reason for a refeed.



The longer the refeed the closer you'll be bringing hormone levels back to normal. A week at maintenance is going to be more beneficial than one refeed day of slightly above maintenance.

A good question would be weighing the pros and cons of a longer refeed vs maximizing fat loss. Would that week at maintenance move things along better or would it lower the potential for fat loss those extra 6 days?

DDon1996
03-08-2011, 09:55 PM
Well, a range of anabolic hormones are elevated which get lowered when dieting apart from leptin. So yeah? :p

I understand that, but upon reading "I've been re-feeding every Saturday thinking I was doing my metabolism a favor. Have I been wasting a day per week eating above maintenance when I could've been burning fat?" It seemed very anti-refeed in general, and I was confused. Just wanted clarification.

MikeK46
03-08-2011, 10:02 PM
Good interview with John Beradi mentioned that

Hah, yea...I read that interview before I made this thread. If you read my first post, I mention some of it.


Because of it's lack of effect on metabolism, correct? That's what I was saying- refeeds are still viable because the downregulation is mediated by a pathway unrelated to leptin.

Is ^^ true?

You aren't specifically disregarding refeeds- but rather arguing against leptin being the driving factor, yeah?

Correct. We currently do not know of any effect it has on metabolism...only hunger.

Yes, I'm a proponent for refeeds for the other reasons (psychological & physiological) mentioned above. Originally I disregarded these reasons (hence I said "am I wasting my time?" but I've since realized that refeeds ARE beneficial for other reasons, and DO affect metabolic rate due to their effect on thyroid hormones). I refeed every Saturday.


A good question would be weighing the pros and cons of a longer refeed vs maximizing fat loss. Would that week at maintenance move things along better or would it lower the potential for fat loss those extra 6 days?

There would not be any fat loss for the week you're at maintenance, obviously. But the restored hormone levels will help move things along nicely once calories are reduced again.

Quelly
03-08-2011, 10:17 PM
That's all practically irrelevant because as soon as you go back to a lower carb intake leptin will drop again almost immediately.

but will that increase in leptin have an effect on other systems in the body that has a lasting effect on metabolism...

like I said, we could debate the mechanism, but it's pretty clear that a high carb refeed drives further fat loss, especially in a lean, depleted state

mynameisuntz
03-08-2011, 11:30 PM
but will that increase in leptin have an effect on other systems in the body that has a lasting effect on metabolism...

like I said, we could debate the mechanism, but it's pretty clear that a high carb refeed drives further fat loss, especially in a lean, depleted state

I think everyone agrees with the second statement (might disagree with the NEED for high carb refeeds, but refeeds in general). What people might disagree with is the mechanism through which this happens. You say leptin, others say not leptin but rather thyroid hormone(s), cortisol, etc.

coals
03-09-2011, 05:47 AM
very interesting read..

goodnight sweet cheatmeals :(


This.

Lollll


(warning; anecdote)
Well, I've noticed while on a harsh cut (1200 cals, psmf, etc) I tend to have much better diet adherence and make faster progress with refeeds than without. So this doesn't change anything for me.


Also the spike in carbohydrates as others have said can have other effects on other regulatory systems. And leptin not effecting metabolic rate directly doesn't mean it's entirely useless, there too many studies showing correlations between lean and fat, the famous mouse study is one (Albeit it's in mice but it's not bad as a model organism). Also it may be worth noting that the carb intake could be affecting something much higher up (dopamine for example ? ) which could affect things such as NEAT and partitioning.

Besides carb spikes cortisol to drop and induce a large drop in water that's typically seen after a refeed.



Also READING ABSTRACTS AND DERIVING CONCLUSIONS IS AN AWFUL HABIT TO DEVELOP.

I'll try to get the full studies through my school so we can look at the methodologies and what have you. I'm not really going to care for a paper if it turns out the whole experiment was done with rats and nothing was measured precisely or we're talking about a bunch of people doing 10 minutes of cardio @ 60% VO2 as "exercise"

MikeK46
03-09-2011, 02:34 PM
but will that increase in leptin have an effect on other systems in the body that has a lasting effect on metabolism...

like I said, we could debate the mechanism, but it's pretty clear that a high carb refeed drives further fat loss, especially in a lean, depleted state

No. Increased leptin is not known to have any impact on anything that affects metabolism. Have you been reading the thread?

It's the increased calories of the refeed that would have an effect on thyroid hormones and therefore metabolic rate. In other words, the refeed doesn't have to be high carb to increase metabolic rate. But making your refeed high carb would also give you the benefits of glycogen replenishment and reduced cortisol on top of the increase in metabolism.

Long story short: Leptin is irrelevant. High calories increase metabolism, high carbs replenish glycogen. Nothing to do with leptin.

JohnBrowne
03-09-2011, 02:37 PM
but will that increase in leptin have an effect on other systems in the body that has a lasting effect on metabolism...

like I said, we could debate the mechanism, but it's pretty clear that a high carb refeed drives further fat loss, especially in a lean, depleted state


No. Increased leptin is not known to have any impact on anything that affects metabolism. Have you been reading the thread?

It's the increased calories of the refeed that would have an effect on thyroid hormones and therefore metabolic rate. In other words, the refeed doesn't have to be high carb to increase metabolic rate. But making your refeed high carb would also give you the benefits of glycogen replenishment and reduced cortisol on top of the increase in metabolism.

Long story short: Leptin is irrelevant. High calories increase metabolism, high carbs replenish glycogen. Nothing to do with leptin.

There is certainly a correlation between leptin and thyroid hormones but there isn't any evidence or logic to suggest that leptin levels somehow dictate thyroid hormone production.

basically x2 on what Mike said

Trillios
03-09-2011, 02:40 PM
It's threads like this that I love and keep me coming back to bb.com.

Quelly
03-09-2011, 02:56 PM
No. Increased leptin is not known to have any impact on anything that affects metabolism. Have you been reading the thread?

It's the increased calories of the refeed that would have an effect on thyroid hormones and therefore metabolic rate. In other words, the refeed doesn't have to be high carb to increase metabolic rate. But making your refeed high carb would also give you the benefits of glycogen replenishment and reduced cortisol on top of the increase in metabolism.

Long story short: Leptin is irrelevant. High calories increase metabolism, high carbs replenish glycogen. Nothing to do with leptin.

To take this stance you have to preferentially ignore some studies and preferentially focus on others, I already posted studies showing high fat overfeeding did not increase energy expenditure while high carb overfeeding did

But there are many other studies. There is a study showing the sensitivity of the leptin receptor in the brain affects RMR, and also influences how much the metabolism slows in response to underfeeding and speeds up in response to overfeeding.

There is another study where they injected leptin post dieting, showing that "During leptin administration, energy expenditure, skeletal muscle work efficiency, sympathetic nervous system tone, and circulating concentrations of thyroxine and triiodothyronine returned to
pre-weight-loss levels"

This was published a full year after the review you posted that published in 2004
"J Clin Invest. 2005 Dec;115(12):3579-86. Links

Low-dose leptin reverses skeletal muscle, autonomic, and neuroendocrine adaptations to maintenance of reduced weight.

Rosenbaum M, Goldsmith R, Bloomfield D, Magnano A, Weimer L, Heymsfield S, Gallagher D, Mayer L, Murphy E, Leibel RL.

Columbia University College of Physicians and Surgeons, New York, New York, USA."

Check it out if you're interested.

That being said, I don't have access to the full text of the 2004 review in question through sport discus or medline, I am trying to hunt down the full text...so I'm going to reserve judgment on it...more than happy to change my mind on the subject....however there has been some interesting discussion about it already with people who have read the full texts...and the talk has been the review mostly looked at overweight and obese populations....you don't see leptin drop below 20-25ng in these folks because of their high bodyfat so leptin won't have an impact on metabolism.

Have you read the full texts on any of the stuff you are talking about, if you have could you pm me? I'd love to look at them. And vice versa.

I am not entrenched in my point of view, and I would advise you not to be either. Learning ends when you try to convince someone else of your point of view and disregard their point before fully considering all sides.

If that's what's happening here I can play elsewhere and hunt down the studies on my own and make my own conclusions.

adean1989
03-09-2011, 03:15 PM
To take this stance you have to preferentially ignore some studies and preferentially focus on others, I already posted studies showing high fat overfeeding did not increase energy expenditure while high carb overfeeding did

But there are many other studies. There is a study showing the sensitivity of the leptin receptor in the brain affects RMR, and also influences how much the metabolism slows in response to underfeeding and speeds up in response to overfeeding.

There is another study where they injected leptin post dieting, showing that "During leptin administration, energy expenditure, skeletal muscle work efficiency, sympathetic nervous system tone, and circulating concentrations of thyroxine and triiodothyronine returned to
pre-weight-loss levels"

This was published a full year after the review you posted that published in 2004
"J Clin Invest. 2005 Dec;115(12):3579-86. Links

Low-dose leptin reverses skeletal muscle, autonomic, and neuroendocrine adaptations to maintenance of reduced weight.

Rosenbaum M, Goldsmith R, Bloomfield D, Magnano A, Weimer L, Heymsfield S, Gallagher D, Mayer L, Murphy E, Leibel RL.

Columbia University College of Physicians and Surgeons, New York, New York, USA."

Check it out if you're interested.

That being said, I don't have access to the full text of the 2004 review in question through sport discus or medline, I am trying to hunt down the full text...so I'm going to reserve judgment on it...more than happy to change my mind on the subject....however there has been some interesting discussion about it already with people who have read the full texts...and the talk has been the review mostly looked at overweight and obese populations....you don't see leptin drop below 20-25ng in these folks because of their high bodyfat so leptin won't have an impact on metabolism.

Have you read the full texts on any of the stuff you are talking about, if you have could you pm me? I'd love to look at them. And vice versa.

I am not entrenched in my point of view, and I would advise you not to be either. Learning ends when you try to convince someone else of your point of view and disregard their point before fully considering all sides.

If that's what's happening here I can play elsewhere and hunt down the studies on my own and make my own conclusions.

Unrelated to the proceedings as I've already expressed my opinion on the subject, but if you want I can try and hunt down a review through my university access, what's the title of this 2004 review?

DDon1996
03-09-2011, 06:17 PM
Have you read the full texts on any of the stuff you are talking about, if you have could you pm me? I'd love to look at them. And vice versa.


Do not leave The Drake out of this.

saw7988
03-09-2011, 06:30 PM
After a quick look at the links in the OP... have you guys been considering the source of the boost in leptin? It looks like those studies use injected leptin, which as Lyle says in multiple articles/books is not even close to the same as replenishing leptin through food. Thoughts on this?

DDon1996
03-09-2011, 06:35 PM
After a quick look at the links in the OP... have you guys been considering the source of the boost in leptin? It looks like those studies use injected leptin, which as Lyle says in multiple articles/books is not even close to the same as replenishing leptin through food. Thoughts on this?

Food has a myriad of physiological effects other than boosting leptin.

saw7988
03-09-2011, 06:37 PM
Food has a myriad of physiological effects other than boosting leptin.

Yea I agree, but I was just trying to say that saying "injecting leptin doesn't increase metabolism" is completely irrelevant. Did I miss any articles that say that "using high carb refeeds to increase leptin doesn't increase metabolism"?

anacoholic
07-13-2011, 02:15 AM
like this thread! 5 stars