James Krieger on Glycemic Index.
SideSteel
Posts: 11,068 Member
A copy pasta from James Krieger, a brilliant man with a head that's damn near as big and misshapen as mine.
"Conclusions in science are always tentative based on the data. When presented with new data, a scientist evaluates that new data against the current body of data, and determines whether current conclusions are supported or should be modified or overturned.
As late as the mid 2000's I was a believer in the insulin hypothesis of fat gain/obesity. As I examined more and more data, it became very clear to me that the insulin hypothesis was completely wrong, so I ditched it. I was also a believer in the glycemic index and its impacts on appetite. However, further examination of data indicated that the GI had minimal impacts on appetite, so I ditched it. In fact, this falls in line with my ditching of the insulin hypothesis (where one aspect says that high carb foods create insulin spikes, leading to reactive hypoglycemia and hunger/overeating).
I wrote this as a comment in another post I made but felt it bears reposting here. It illustrates the accumulated data which overturned my thinking regarding the glycemic index and appetite.
There's been a number of studies over time that have led me away from considering GI as an important factor in appetite regulation (I used to believe it was, but there's too much data that has made me change my mind).
One of the first studies in fact was done by Jennie Brand Miller, one of the big GI proponents. They tested 38 different foods and looked at factors that predicted satiety. GI was not one of them. Rather, energy density, protein, fiber, and palatability were predictors of satiety.
http://www.ncbi.nlm.nih.gov/pubmed/7498104
In another study by the same authors, glucose responses were not predictive of satiety.
http://www.ncbi.nlm.nih.gov/pubmed/8968699
In a meta-analysis of studies, glucose responses were not predictive of satiety.
http://www.ncbi.nlm.nih.gov/pubmed/17524176
Energy density and fiber are big confounders in GI studies. When you control for these things, the impact of GI is either weak or non-existent.
For example, in this study, which controlled for energy density, macro nutrient content, and fiber, a low GI meal only had a very small effect on feelings of
fullness, and there was no impact on actual energy intake.
http://www.ncbi.nlm.nih.gov/pubmed/21775528
In this ad lib study which controlled for the same factors, there was no impact on satiety.
http://www.ncbi.nlm.nih.gov/pubmed/17923862
Another ad lib study which controlled for these factors, with no impact on satiety
http://www.ncbi.nlm.nih.gov/pubmed/15277154
In an extremely well controlled, well designed 8-day study in the lab, which controlled for macronutrient content and palatability, GI was not related to
appetite ratings or food intake.
http://www.ncbi.nlm.nih.gov/pubmed/16123477
On top of all that, it's been found that the GI of a particular food is highly variable from one person to the next, and even highly variable from day to day within the same person, making it unreliable.
http://www.ncbi.nlm.nih.gov/pubmed/23822709
http://www.ncbi.nlm.nih.gov/pubmed/18186950
For all of these reasons, I do not consider the GI a very useful tool in constructing high satiety diets. On top of that, being focused on GI can lead people to avoid certain high GI foods that are, in fact, very satiating and nutritious (like potatoes)."
"Conclusions in science are always tentative based on the data. When presented with new data, a scientist evaluates that new data against the current body of data, and determines whether current conclusions are supported or should be modified or overturned.
As late as the mid 2000's I was a believer in the insulin hypothesis of fat gain/obesity. As I examined more and more data, it became very clear to me that the insulin hypothesis was completely wrong, so I ditched it. I was also a believer in the glycemic index and its impacts on appetite. However, further examination of data indicated that the GI had minimal impacts on appetite, so I ditched it. In fact, this falls in line with my ditching of the insulin hypothesis (where one aspect says that high carb foods create insulin spikes, leading to reactive hypoglycemia and hunger/overeating).
I wrote this as a comment in another post I made but felt it bears reposting here. It illustrates the accumulated data which overturned my thinking regarding the glycemic index and appetite.
There's been a number of studies over time that have led me away from considering GI as an important factor in appetite regulation (I used to believe it was, but there's too much data that has made me change my mind).
One of the first studies in fact was done by Jennie Brand Miller, one of the big GI proponents. They tested 38 different foods and looked at factors that predicted satiety. GI was not one of them. Rather, energy density, protein, fiber, and palatability were predictors of satiety.
http://www.ncbi.nlm.nih.gov/pubmed/7498104
In another study by the same authors, glucose responses were not predictive of satiety.
http://www.ncbi.nlm.nih.gov/pubmed/8968699
In a meta-analysis of studies, glucose responses were not predictive of satiety.
http://www.ncbi.nlm.nih.gov/pubmed/17524176
Energy density and fiber are big confounders in GI studies. When you control for these things, the impact of GI is either weak or non-existent.
For example, in this study, which controlled for energy density, macro nutrient content, and fiber, a low GI meal only had a very small effect on feelings of
fullness, and there was no impact on actual energy intake.
http://www.ncbi.nlm.nih.gov/pubmed/21775528
In this ad lib study which controlled for the same factors, there was no impact on satiety.
http://www.ncbi.nlm.nih.gov/pubmed/17923862
Another ad lib study which controlled for these factors, with no impact on satiety
http://www.ncbi.nlm.nih.gov/pubmed/15277154
In an extremely well controlled, well designed 8-day study in the lab, which controlled for macronutrient content and palatability, GI was not related to
appetite ratings or food intake.
http://www.ncbi.nlm.nih.gov/pubmed/16123477
On top of all that, it's been found that the GI of a particular food is highly variable from one person to the next, and even highly variable from day to day within the same person, making it unreliable.
http://www.ncbi.nlm.nih.gov/pubmed/23822709
http://www.ncbi.nlm.nih.gov/pubmed/18186950
For all of these reasons, I do not consider the GI a very useful tool in constructing high satiety diets. On top of that, being focused on GI can lead people to avoid certain high GI foods that are, in fact, very satiating and nutritious (like potatoes)."
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Replies
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Thank you0
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queenliz99 wrote: »Thank you
Anytime!0 -
Great research review by Krieger. Thanks for posting it!0
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Who ?0
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I love this so much. I did a post on GI a while back, and when I really dug into a lot of the research, my jaw dropped at how the studies were designed and what they were comparing. It's good to see some research with good controls in place giving more useful information. David Ludwig has lots to answer for.
Thanks for posting this!0 -
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DeguelloTex wrote: »
aha, did I miss the link (apart from the Pubmed ones)0 -
DeguelloTex wrote: »
aha, did I miss the link (apart from the Pubmed ones)
His main site is at www.weightology.net0 -
How can protein and fiber impact satiety without GI impacting satiety? Don't protein and fiber directly impact GI?0
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Need2Exerc1se wrote: »How can protein and fiber impact satiety without GI impacting satiety? Don't protein and fiber directly impact GI?
Protein and fiber content are part of what helps determine the GI of a food, but others things are also a factor. The point, I think, is that protein and fiber content are linked to satiety, while GI isn't.0 -
janejellyroll wrote: »Need2Exerc1se wrote: »How can protein and fiber impact satiety without GI impacting satiety? Don't protein and fiber directly impact GI?
Protein and fiber content are part of what helps determine the GI of a food, but others things are also a factor. The point, I think, is that protein and fiber content are linked to satiety, while GI isn't.
I understand what they are saying. I'm just not understanding how it works when they are linked to each other? Maybe if I weren't too lazy to read the links I'd know.
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Need2Exerc1se wrote: »janejellyroll wrote: »Need2Exerc1se wrote: »How can protein and fiber impact satiety without GI impacting satiety? Don't protein and fiber directly impact GI?
Protein and fiber content are part of what helps determine the GI of a food, but others things are also a factor. The point, I think, is that protein and fiber content are linked to satiety, while GI isn't.
I understand what they are saying. I'm just not understanding how it works when they are linked to each other? Maybe if I weren't too lazy to read the links I'd know.
I think (someone jump in if I'm wrong) is that there are many other factors involved and the protein and fiber content of a food may not be the strongest factors in determining the GI content of a given food. For example, ice cream and pure fructose are low GI foods (which isn't what you'd expect if protein and fiber were the main factors used to determine GI). There's a connection, but it isn't as strong as some would lead us to believe.
If protein and fiber are what we want, it's much better to look at those directly instead of GI, which is linked to those and many other things.0 -
janejellyroll wrote: »Need2Exerc1se wrote: »janejellyroll wrote: »Need2Exerc1se wrote: »How can protein and fiber impact satiety without GI impacting satiety? Don't protein and fiber directly impact GI?
Protein and fiber content are part of what helps determine the GI of a food, but others things are also a factor. The point, I think, is that protein and fiber content are linked to satiety, while GI isn't.
I understand what they are saying. I'm just not understanding how it works when they are linked to each other? Maybe if I weren't too lazy to read the links I'd know.
I think (someone jump in if I'm wrong) is that there are many other factors involved and the protein and fiber content of a food may not be the strongest factors in determining the GI content of a given food. For example, ice cream and pure fructose are low GI foods (which isn't what you'd expect if protein and fiber were the main factors used to determine GI). There's a connection, but it isn't as strong as some would lead us to believe.
If protein and fiber are what we want, it's much better to look at those directly instead of GI, which is linked to those and many other things.
Ah got it.0 -
And the controlling for fiber was just done by making sure that the control meals had the same amount of fiber but at a higher GI/GL. So that checks to see if it was the fiber causing it, not GI itself.
I agree that you can't (and shouldn't try to) separate fiber from GI, because it's usually key in why some foods are low
At least one of those studies did show a significant result on satiety, so I don't know that I would have included it in here. Maybe it's in here because in the real world, the size of the effect matters! In the reasoning of studying these things, though, it might be an important finding. If they can understand why it works (even a little but significant bit), that finding could be manipulated as a drug target or similar. 0 -
Interesting, thanks!0
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A copy pasta from James Krieger, a brilliant man with a head that's damn near as big and misshapen as mine.
...
As late as the mid 2000's I was a believer in the insulin hypothesis of fat gain/obesity. As I examined more and more data, it became very clear to me that the insulin hypothesis was completely wrong, so I ditched it. I was also a believer in the glycemic index and its impacts on appetite. However, further examination of data indicated that the GI had minimal impacts on appetite, so I ditched it. In fact, this falls in line with my ditching of the insulin hypothesis (where one aspect says that high carb foods create insulin spikes, leading to reactive hypoglycemia and hunger/overeating).
...
I had never read Krieger's work on insulin hypothesis, but I found an article here:
http://weightology.net/weightologyweekly/index.php/free-content/free-content/volume-1-issue-7-insulin-and-thinking-better/insulin-an-undeserved-bad-reputation/
Great stuff, thanks.
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Another good post by SS. Thanks bro.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
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Great post @SideSteel0
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