Talk:Calorie restriction
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[edit] Numbered References
I think we need to put in some numbered references next to a lot of claims so that we can associate them with the texts that have shown evidence for such changes. Any thoughts? --Unknown
- I agree. Also the part on "Objections to Calorie Restriction" needs a reference to who this michael cooper fellow is. // Lasse
[edit] Moved positive info from Objections to Why
Thx for the good article. I found pro-cr info in Objections and moved it to near the end of "Why might CR increase longevity?" I don't know enough about this to rewrite much (except for one copyedit), so flow could use some work. Also, the last paragraph i moved ("Stated levels of Calorie needs may be biased towards sedentary individuals. Calorie Restriction may be more of adapting the diet to the body's needs.") should be explained more -- i wasn't sure what it meant and where to put it. Does this relate to the activity level question in test animals, and if so how? If "Calorie needs [are] biased towards sedentary individuals" vs active ones, wouldn't that mean they're too *low*? Etc. Hope this helps, "alyosha" (talk) 23:26, 3 January 2006 (UTC)
[edit] Should be changing inital text
- "Except for houseflies (below), animal species tested with CR so far, including primates, rats, spiders and rotifers, have shown lifespan extension"
This statement isn't as correct as it should be. There has been no lifespan extention demonstrated in a published paper with primates. Richard Weindruch's experiments are ongoing and there has been nothing published stating that "lifespan extension" has been "shown". So unless someone puts forth a concluded published trial with primates I'm going to change this. 205.211.168.10 15:02, 7 February 2006 (UTC) Jonathan Graham
Also I added to the Objections section a link to the Housefly article and some text about John Phelan's objection about this being an effect that is really only acheivable on small organisms. Another good reason to change the intro text. Not saying that this wiki is biased but it looks like there has been way more effort put into representing the "pro" side here. 205.211.168.10 15:24, 7 February 2006 (UTC) Jonathan Graham
Searched around for completed primate studies, nothing so far. I did find another ongoing one (other than the one by RW). It shows some evidence at monkeys beating the median age ( I'll read the study in a bit more detail later but that seems like grade 'C' evidence when dealing with such a small sample ) If they were to beat the maximal age that would really drive the point home but considering that these monkeys live 40 years...I wouldn't expect a conclusion any time soon. Also Rhesus monkeys are prone to diabeties which would skew the results somewhat as well.
Also added the study about late-life CR. I'm not sure if we should put an approximate age in there. The rats were introduced at 18 months - what would that be in human years. I've seen places where people have just assumed that you compose them linearly but is it really reasonable to do so.
I've put it under 'objections' which is becoming a less and less applicable title. It sort of depends on exactly what one is 'objecting' to. If this article is about simple calorie restriction as having some (possibly small) benefit on some arbitrary group of creatures then they aren't but in reading this article, it appears to me that what is being advertised here is CR as a generally applicable lifestyle for significant (i.e. greater than maximal) longevity with implication on the idea the humans can do this too. In which case I would call the articles I'm posting "objections". I would think this isn't such a bad thing to be discussing either after all when you read about CR in the media, they aren't talking about how to keep your pet rat alive longer! :-)
205.211.168.10 20:40, 7 February 2006 (UTC)Jonathan Graham
More digging through PM...and we find out that this effect (longevity) may not even be consistant on small organisms. Drosphila may have mixed responses when it comes to CR - at least from the journal abstracts. Also there's a reference to a mouse study that didn't produce longevity. I'll go through these articles when I get a chance. Point being that this wiki, so far makes it sound like there is little reason to believe that this effect isn't universal but now I'm thinking we may want to tone it down a bit.
24.141.146.87 01:14, 8 February 2006 (UTC)Jonathan Graham
[edit] Walford and Weindruch
Great catch, that's interesting why credit was only given to the student... although he was still the one to report them? Maybe teachers do that to give their underlings a better chance at success later, when they are satisfied. Tyciol 16:38, 14 February 2006 (UTC)
[edit] Benefits only the young?
There's oodles of evidence that CR benefits exist at all ages. Too rapid introduction of CR is the problem in the few studies that don't show that. This section should be removed. /--Borgipedia 18:36, 19 July 2006 (UTC)
[edit] Names of researchers
This article quotes the names of many of the researchers, but I couldn't find any reference to the David Sinclair mentioned in Sir2. is this a mistake? --apers0n 15:33, 28 July 2006 (UTC)
- Not sure what you mean — that no one has yet found the reference to the claim attributed to him? /--Borgipedia 15:56, 28 July 2006 (UTC)
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- Well I looked at the studies attributed to him and couldn't find his name mentioned anywhere, but wasn't sure if Sinclair is a notable person in the world of CR, in which case there should be a reference to him. It is unusual to name the researchers in a reference article like this unless describing a historical sequence of e.g. the first person to discover the benefits of CR was... or a notable person (such as someone who has their own biography on Wikipedia - see Dave Sinclair - Keyboard player from Caravan). A better place for the names of researchers is in the references/notes section.
- Example: "Studies by Mark P. Mattson, PhD, chief of the National Institute on Aging's (NIA) Laboratory of Neurosciences, and colleagues have found that..." - surely the occupation of Mark P. Mattson, PhD belongs on the page for the NIA? --apers0n 06:30, 29 July 2006 (UTC)
[edit] Martin Brookes comment
To Mccready: Why do you want Brookes comment here in the intro? The intro paragraph introduces CR, and (like CR) makes no claims about single or multiple causes of aging. Thanks in advance. --Borgipedia 09:36, 21 August 2006 (UTC)
- needs context Mccready 08:52, 22 August 2006 (UTC)
What do others think? Anyone? Seems like a bizarre thing in this intro paragraph. Mccready: perhaps you can add more than your two words here? The question of the absence or presence of single causes of aging seems like weird "context." What do you mean? Thanks. --Borgipedia 14:51, 22 August 2006 (UTC)
You asked me to discuss. I did. You didn't. I'm removing it. Please justify, here, putting back before you put it back. --Borgipedia 15:36, 5 September 2006 (UTC)
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- CR is one of the most prominent techniques for allegedly reducing aging in humans (please remember that it is not proven in humans). As such, we owe it to the readers of this article to provide some context. There is nothing weird or bizarre about this comment from a scientist. I'll replace now. Mccready 19:58, 5 September 2006 (UTC)
Your quotation makes the point, indeed, stresses the point, that aging doesn't have one single cause. What does that have to do with the introductory paragraph in this article about CR, which (para. and article) rightly makes no claims about the number of causes of aging? /--Borgipedia 15:16, 6 September 2006 (UTC)
- Are you being dense or playing at wikilawyering? CR claims by implication if not directly that a major cause of aging is related to calorie intake. It's got nothing to do with any number. I'm reverting. Mccready 15:05, 11 September 2006 (UTC)
Please read the article, and/or read up on CR. You don't know enough about it to understand how to edit this article. CR itself doesn't "claim" anything, but advocates of CR believe that CR can affect various aspects of aging. No one argues that calorie intake is a direct cause of aging. I see from your other posts you have an axe to grind. Grinding it here is probably not a good idea. James Randy-ism isn't apposite here. Thanks. /--Borgipedia 18:01, 11 September 2006 (UTC)
[edit] Body temperature relation?
Lowering the body temperature of mice resulted in significant longevity increase:
http://www.livescience.com/animalworld/061102_cool_mice.html
From the article:
"Past studies have shown lifespan can be extended in animals by cutting down on the calories in their diets. Interestingly, this method also lowers body temperature. "The mechanisms mediating the increased lifespan in the 'cool mice' may be similar to those of calorie restriction," Conti speculated."
--Cheese Sandwich 13:36, 4 November 2006 (UTC)
[edit] Article Organization (species section)
This is either a note to myself for when I have more time, or a request for others watching this page. Is it useful to have the section "effects on different organisms?" Several sections are stubs, and amount basically to "this species has been shown to live longer." The exception currently is the section on Rats, but clearly most of that material should be moved to the section "Why might CR effect longevity?"
It seems to me a more useful organization might be "Effects Of CR" and then, rather then divide it into species subtopics, divide it into outcome subtopics. "Increased longevity" - Longevity has been verified in mice, rate, c. elegans, etc.; "Decreased rates of Cancer", "Improved cardiovascular function", "Lower free radical damage" - etc., in each case noting in which species the benefit has been verified. This would take some work - a meta-analysis of what's been published, and a fair amount of referencing - but it strikes me as a much more useful organization. Each section could also, of course, note when the benefit has not been observed. Comments? SJS1971 11:41, 9 November 2006 (UTC)
[edit] CR vs. lean
In current human practice, what is the difference between CR and being skinny/lean/lowbodymass/smallwaisted? Is the only difference getting good nutrition? Is there any difference? Can you be doing CR and still maintain a relatively high weight? Should you? Does practicing CR imply being low-energy and exercising little? Or imply the opposite? This should all be clearly addressed in a section of the article. And there also needs to be a good wiki article on the plain relation of body mass to longevity, with a prominent See also link from here. 69.87.203.106 14:17, 18 November 2006 (UTC)
[edit] Biosphere Two significance
I think it should be mentioned in the article the results and link to Calorie Restriction obtained through Biosphere Two by Roy Walford. Evidence can be cited here:
- http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12023257&dopt=Abstract - Peer-reviewed Journal Article
- http://www.lef.org/protocols/lifestyle_longevity/caloric_restriction_01.htm - Direct link to Calorie Restriction
| The eight people living in Biosphere 2, an enclosed ecosystem, underwent involuntary caloric restriction during their 2-year stay because they were unable to grow enough food for their needs. They consumed 1800 calories per day during the first 6 months and 2200 calories thereafter. Their diet was nutrient rich and high in vegetables. Body weight decreased by 15 percent and serum cholesterol dropped 38 percent. Blood pressure fell from an average of 110/74 millimeters of mercury (mm Hg) to 90/59 mm Hg. A group outside Biosphere 2, who ate without restriction but who took the same nutritional supplements as those inside Biosphere 2, did not exhibit these same positive health alterations |
| -- Walford RL et al 2002 |
The Biosphere project unintentionally became a significant study on calorie restriction on humans in a completely isolated environment - an important control variable.
P.S. Sorry for the alignment of the quote, it's from the second external link I put up. -- Permafrost 03:21, 10 February 2007 (UTC)
[edit] Intermittent Fasting
There should be a new article specifically on Intermittent Fasting, because that has proven to be a superior method of life-extension in animals, and perhaps humans. The benefits of intermittent fasting seem to be independent of Calorie Restriction (CR). For example, fasted mice eating as much as controls showed superior results to those eating only 60% as much (40% CR). This brings into question the whole theory of CR, because the same benefits (and more) can be had WITHOUT restricting calories. —Preceding unsigned comment added by 65.80.77.27 (talk • contribs) 10:27, 9 April 2007
- In this study there was another group which ate as much as the intermittent fasting (IF) group, called the pair-fed (PF) group. This group also showed "superior results" (only in the experiment where neurotoxins are directly injected into the brain...), but the study is thin on details about this group. They didn't let the mice live long enough to be able to say how the lifespans compared. Intermittent fasting is certainly not proven to be a superior method of life extension. And please if you write about such studies, only look at the original paper, not at some media gossip. Icek 11:18, 22 July 2007 (UTC)
[edit] Policy on sourcing
I reverted an unsourced addition of content, and the editor who made it then reverted it back: [1]. I try to follow a one-revert rule, so I will not revert it again. I asked the editor for more clear sourcing, but my request was refused: [2]. According to Wikipedia:Verifiability "Articles should only contain material that has been published by reliable sources. Editors adding or restoring material that has been challenged or is likely to be challenged, or quotations, must provide a reliable published source, or the material may be removed." Is a citation to "Charlie Rose - calorie restriction" satisfactory detail for this material, or should we raise the bar on the article sourcing to comply with WP:CITE and WP:RS? Buddhipriya 07:53, 15 July 2007 (UTC)
- When I type that in to google it gives a youtube copy as the very first hit and the same under yahoo; with all due respect, you have no case whatsoever under the wikipedia policies. You also have no power to unilaterally raise or lower bars on individual articles within the wikipedia.WolfKeeper 15:48, 15 July 2007 (UTC)
[edit] Precise amount of intake calories
A normal amount of kcal a person consumes is around 2800-3000kcal/day, is it possible to include in this article how much is consumed with this caloric restriction diet/day? —Preceding unsigned comment added by 81.244.193.44 (talk) 08:58, August 29, 2007 (UTC)
[edit] Genetics Inaccuracies
"Sir2 or "silent information regulator 2" is a longevity gene in baker's yeast cells that extends lifespan by suppressing DNA instability (see Sinclair and Guarente, Cell, 1997).[10] In mammals Sir2 is known as SIRT1. Recent discoveries have suggested that the gene Sir2 might underlie the effect of CR. In baker's yeast the Sir2 enzyme is activated by CR, which leads to a 30% lifespan extension."
These statements are entirely inaccurate. Sir2 is not a "longevity gene", it has multiple responsibilities. Of primary importance is its role in cell division. My understanding of the literature, which is by no means extensive, is that CR increases Sir2 expression. Sir2, I believe, has 7 mammalian homologs SIRT1-7. SIRT1 is active in the nucleus. SIRT3 is an inter membrane mitochondrial enzyme which may play a role in regulation of thermogenesis, it is found primarily in the brown adipocye mitochondria. I don't know about the rest.
As for the 30% part, I have no idea what studies are showing and thus have no objections except for the lack of a citation. I intend to remedy my own lack of citations for above statements. —Preceding unsigned comment added by Backwardtoes (talk • contribs) 22:19, 25 October 2007 (UTC)
[edit] CRON-diet article
A new article is to come for the CRON-diet (which uses calorie restriction)
The Calorie Restriction with Optimal Nutrition-diet is a low calorie, high nutrition- diet which practices the limiting of dietary energy intake in the hope that it will improve health and retard aging.
This first line already shows that more low-high diets exist and can be used with the okinawa diet article aswell.
Dont have time to look up the references, found it in the health plan book of roy walford. Look into it and change article.
KVDP (talk) 15:14, 1 February 2008 (UTC)
[edit] The CRON-diet in practice
a new section would need to describe the CRON-diet in practice. It is to include: standard CR diet which is proposed (and still safe) features 5-25% CR restriction (it can go up to 60% in theory yet no longer safe). Standard diet recomendations are usually to begin with 1800 calories/day. Further work out may happen as this is a guideline(biospherians ate 1800 calories/day, yet had to work physically hard). basal metabolic rate of person cannot be accuratly measured (thus trial and error method is to be followed aldough trough the fat percentage some indications may be given on the amount of calorie intake a person must follow, as body fat should not drop below (6% for a man and 10% for a woman) KVDP (talk) 10:43, 2 February 2008 (UTC)
