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Weight Loss Forum / Low Carb / March 2006Glycemic Index 'Unrealistic' and Not Very Useful
The glycemic index, a current hot diet trend, "does not seem useful in understanding how diet impacts health, it only makes life more complicated for those trying to adopt a healthier lifestyle." says the author of a new study. http://www.diabetesincontrol.com/modules.php?name=News&file=article&sid=3552 Yes...eat low fat and more gains....and watch that T2 spin out of control. I have watched my father do this for years. Rick > The glycemic index, a current hot diet trend, "does not seem useful in > understanding how diet impacts health, it only makes life more complicated > for those trying to adopt a healthier lifestyle." says the author of a new > study. > > http://www.diabetesincontrol.com/modules.php?name=News&file=article&sid=3552 These statements seem reasonable, just not very relevant to dieting. Keeping an eye on GI does seem to help alot of people manage cravings etc. Anyway, GI is mostly a way for all the diet gurus to promote Atkins without looking like idiots after slagging it off for 20 years. Pete -- 287/195/185 > Anyway, GI is mostly a way for all the diet gurus to promote Atkins > without looking like idiots after slagging it off for 20 years. > > Pete > -- > 287/195/185 AMEN! > The glycemic index, a current hot diet trend, "does not seem useful in > understanding how diet impacts health, it only makes life more complicated > for those trying to adopt a healthier lifestyle." says the author of a new > study. > > http://www.diabetesincontrol.com/modules.php?name=News&file=article&sid=3552 Perhaps a relevant extract is: > The general ‘take-home’ message for consumers has been “low GI good, high GI bad.” > [quoted text clipped - 16 lines] > > “This is unrealistic because we eat throughout the day, and a certain food eaten at lunchtime can have a different impact on blood-glucose levels compared to eating that same food for breakfast after fasting overnight,” said Mayer-Davis. “In general, the GI does not seem to be useful in understanding how diet impacts health, and use of the GI may not be an effective way to identify foods for optimal health,” she said. I remember reading that in real eating, you mix up a lot of foods of differing GI and GL (Glycemic Indices and Glycemic Loads).... and the resulting increase in Blood Glucose has little to do with the net composition of the mix of foods eaten. It has long been known that Protein or Fat eaten along with high GI/GL foods will knock down the BG rise substantially. The GI and GL stuff is overhyped, and gives those chemically disadvantaged a feeling that they are able to make predictions of some sort. In reality, the chemistry of digestion is more complex than GI/GL because of the complexities of interactions of foods in the digestive tract. Yes, I was foolish enough to buy into this at first myself. Finally, my real knowledge of the difference between complex systems and simple isolated test results took over. We pay a high price for being scientifically semi-literate. It allows others to manipulate our good intentions. Jim :: Yes, I was foolish enough to buy into this at first myself. When it's all said and done, just controlling carb intake while not overeating is mostly what's needed (exercise, too!) > I remember reading that in real eating, you mix up a lot of foods of > differing GI and GL (Glycemic Indices and Glycemic Loads).... and the > resulting increase in Blood Glucose has little to do with the net > composition of the mix of foods eaten. That is not true .... it has everything to do with it. There is a formula to calculate the GI of a meal based on GI's of its individual components. I am surprised that no one has taken this study to task. After years of flawed studies that bashed low carb, I would think that old-timers on this group would be suspicous. This study allowed diabetics to eat low-glycemic carbs freely then measured their blood sugar. Diabetes is a disease of poor carbohydrate metabolism. If you eat 300 grams of "fast" carbs, they have to be metabolized. If you eat 300 grams of "slow" carbs, they have to be metabolized. The advantage of low GI carbs is that they get to your blood stream over a longer period of time than the fast ones and, because of that, you can probably eat a few more than you could of the fast ones. If you exchange the same number of fast carbs for slow carbs, then you will probably have lower blood glucose numbers because the impact is spread over a longer time period. Cookie It's not even clear to me what exactly they did in this study. It sounds like they just asked people what they ate over a long period of time and measured there BG levels. Now if these people were all eating a wide assortment of different foods, some foods with high GI, some with low GI, I'm not so surprised that it was hard to find any difference. Now it would have been more interesting to divide them in two groups, with one group eating low GI foods and the other hi GI and then see what happens. > It's not even clear to me what exactly they did in this study. It > sounds like they just asked people what they ate over a long period > of time and measured there BG levels. Now if these people were all > eating a wide assortment of different foods, some foods with high > GI, some with low GI, I'm not so surprised that it was hard to find > any difference. And anyone who's spent much time in this newsgroup knows how reliable asking people about their own diets is. If they aren't externally monitoring and measuring what the subjects are eating, I'd say the entire study is worthless.  SignatureAaron -- aaron_baugher@yahoo.com -- 285/235/200 http://360.yahoo.com/aaron_baugher >> I remember reading that in real eating, you mix up a lot of foods of >> differing GI and GL (Glycemic Indices and Glycemic Loads).... and the [quoted text clipped - 4 lines] > formula to calculate the GI of a meal based on GI's of its individual > components. Can you show the "alleged formula" .... And can you show any expeirment in which the ability of the formula to PREDICT actual Blood Glucose response is VERIFIED? I'll bet not. The chemistry is too complex for the simple "Rule of Mixtures" type of rule to apply. Rule of mixtures: Aggregate response = summation of portion weighted responses of the components. These simple models are based on the lack of interaction between foods in the stomach... but there is competition for enzymes, for example, as just one of many interactions of foods digesting in the stomach. Anything more complicated is not useful to the average "math limited" dieter, or would be just too much trouble even if the math could be performed. I am sure that there is no EXPERIMENTALLY VERIFIED formula for GI/GL response of food mixtures. I, of course, will follow up with any references you can provide. > I am surprised that no one has taken this study to task. After years of > flawed studies that bashed low carb, I would think that old-timers on [quoted text clipped - 10 lines] > > Cookie > >> I remember reading that in real eating, you mix up a lot of foods of > >> differing GI and GL (Glycemic Indices and Glycemic Loads).... and the [quoted text clipped - 6 lines] > > Can you show the "alleged formula" .... Yes, I'd like to see it too. > And can you show any expeirment in which the ability of the formula to > PREDICT actual Blood Glucose response is VERIFIED? [quoted text clipped - 21 lines] > > I, of course, will follow up with any references you can provide. Plus whatever the alleged formula is, assuming that the resulting GI from mixing lower GI foods with higher is still a net result that is lower than eating just high GI foods, then why didn't it show up in this study? I think another issue with this study is that it apparently was done with diabetics? Not sure how this then translates to normal subjects. > > I am surprised that no one has taken this study to task. After years of > > flawed studies that bashed low carb, I would think that old-timers on [quoted text clipped - 10 lines] > > > > Cookie :: Jbuch wrote: ::: Cookie Cutter wrote: [quoted text clipped - 48 lines] :: with diabetics? Not sure how this then translates to normal :: subjects. Well, for normal subjects it won't matter much, right? They aren't IR and won't have insulin swings, so they can basically eat whatever. Until the can't, of course. :::: I am surprised that no one has taken this study to task. After :::: years of flawed studies that bashed low carb, I would think that [quoted text clipped - 12 lines] :::: :::: Cookie > :: Jbuch wrote: > ::: Cookie Cutter wrote: [quoted text clipped - 52 lines] > won't have insulin swings, so they can basically eat whatever. Until the > can't, of course. Don't people without diabetes have swings in BG depending on what they eat? Seems Atkins spent a lot of time talking about this, including recommending against caffeine, because it could cause blood sugar swings. And I seem to recall studies done on sugar alcohol showing how some had more impact on BG than others > :::: I am surprised that no one has taken this study to task. After > :::: years of flawed studies that bashed low carb, I would think that [quoted text clipped - 12 lines] > :::: > :::: Cookie > Don't people without diabetes have swings in BG depending on what they > eat? Seems Atkins spent a lot of time talking about this, including > recommending against caffeine, because it could cause blood sugar > swings. And I seem to recall studies done on sugar alcohol showing > how some had more impact on BG than others People with intact pancreatic function mostly stay in a tight range of 85-105 no matter what they eat. There's a progression of worsened glucose tolerance between completely intact and diabetic ranges during which increased bg swings occur. But even without the swings in bg, we know that the high amount of insulin secretion needed to manage high carb intake is although unhealthy; it's associated with CVD and higher incidence of some cancers. Susan > Can you show the "alleged formula" .... > > And can you show any expeirment in which the ability of the formula to > PREDICT actual Blood Glucose response is VERIFIED? > > I'll bet not. OJ = Orange Juice, 4 oz CF = Kellogg's Corn Flakes, 1 oz M = Milk, 4 oz T = 1 slice of toast Carb = Grams of Carbohydrate in the food %Tot_Carb = %of total carbohydates supplied to the meal by this food GI = Glycemic Index Contribution = The GI contributed by this food to the mixed meal Food..Carb...%Tot_Carb.....GI.....Contribution ----..----........----.....--.....------------ OJ.....13.........23.......46....23% * 46 = 11 CF.....24.........43.......84....43% * 84 = 36 M ..... 6.........11.......27....11% * 27 = 3 T .....13.........23.......70....23% * 70 = 16 ............................................___ TOTAL GI for Meal .......................... 66 Mixed meals have been tested at the University of Sydney. Formula is from "The Glucose Revolution, The Authoritative Guide to the Glycemic index" by Jennie Brand-Miller, et al. This edition was published in 1999 and can be purchased at used book websites. The second edition called "The New Glucose Revolution" is geared to a non-technical audience and does not have a technical chapter containing the scientific explanations of the previous book including this formula. Cookie :: Jbuch wrote: :: [quoted text clipped - 34 lines] :: containing the scientific explanations of the previous book :: including this formula. In other words, a major BG roller coaster ride. But we knew that from the total carb count. >> Can you show the "alleged formula" .... >> [quoted text clipped - 33 lines] > > Cookie Thanks, but what is here is "that the mixed meals have been tested at the University of Sydney". You can test all kinds of things and that testing doesn't mean anything if you don't explicitly REPORT RESULTS. This text doesn't say that the meal prediction was VERIFIED. That would be to list the prediction and the observation. The observation would be the predicted glucose spike and the observed glucose spike...... preferably with a graph showing the buildup and the peak. But at least to explicitly compare the predicted blood spike with the observed. Again, I can have a theory and claim to have tested something. If I don't report that the test did/didn't verify the theory, and show the results, then I have mislead the reader. And, of course, one would have to verify the formula with a lot of different mixtures to show that it is generally applicable to mixtures of meals, and not just one lucky statistical hit. The above meal consisted of Orange Juice, Cereal, Milk and Toast. It didn't include fatty breakfast sausage..... which is often quoted as slowing down the Blood Glucose spike. It didn't include lean meaty beef, which is also often quoted as a way of slowing down the glucose spike. As far as I can see.... the above shows a linear rule of mixtures prediction --- which generally fails in many situations in real life. I made my living as a metallurgist for a while. Part of metallurgy involves mixing two or more metals together to create an allow. The simple linear rule of mixtures almost never produces an accurate answer because nonlinear chemical reactions happen. Anyone who could create a formula to predict the properties of mixtures of metals could end up quite rich. "Magic Formulas" for complex real physical situations usually don't exist except in the minds of .............. Thank you for presenting the source of your opinion. I can see how you could easily have formed your opinion. Signature1) Eat Till SATISFIED, Not STUFFED... Atkins repeated 9 times in the book 2) Exercise: It's Non-Negotiable..... Chapter 22 title, Atkins book 3) Don't Diet Without Supplemental Nutrients... Chapter 23 title, Atkins book 4) A sensible eating plan, and follow it. (Atkins, Self Made or Other) :: The simple linear rule of mixtures almost never produces an accurate :: answer because nonlinear chemical reactions happen. [quoted text clipped - 4 lines] :: "Magic Formulas" for complex real physical situations usually don't :: exist except in the minds of .............. GI/GL is so complicated....mixtures and non-linear effects. A big "Argh" in the real world with real people. Simple: limit carb intake grams. Works well. KISS. |
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