As many of you are aware, Atkins Nutritionals have devised a new "seal" wherein they will replace the term "net carbs" with the term "Net Atkins Count" (a proprietary term.) This labeling rests loosely on the glycemic index — putting the GI back in the forefront of media attention. So, we've asked our Expert Panel members to comment on the Glycemic Index and whether they feel it has (or doesn't have) value.

It's important to remember that not all members of our Expert Panel will agree with one another. And that we (Low Carb Luxury) may not necessarily always agree with our panel members. But each of them bring some valuable insight to the table. And each has tried to share their viewpoints and reasons behind them.

Our background and explanation is from Gil Wilshire, M.D., Medical Director, Technology Catalysts International Corp. of Falls Church, Virginia this month. We thank him for writing such an in-depth piece in response to our query.

Glycemic Index (GI) and Glycemic Load (GL, a.k.a. total carbohydrate) are two concepts that have significant similarities and significant differences.

The GI is an estimation of the speed and height of the blood sugar peak after eating (i.e. the post prandial glucose curve). The GI, therefore, is an aid to individuals with diabetes (who need to tailor their insulin or other medication requirements), or to people with with hypoglycemia (who may benefit from prolonged, steady release of sugar from the gut). The GI does not reflect the Area Under the Curve (AUC) or total amount of carbohydrate that is actually released into the circulation. The AUC is a crucial concept to understand to be able to wrap one's head around these issues.

GL best reflects the amount of total carbohydrate that is contained in a food. For traditional carbohydrates, this more accurately reflects the AUC of post-prandial blood sugar, and indirectly, the amount of insulin (i.e. fat-storing hormone) released after eating. Insulin levels are just one piece of the fat metabolism picture, however, and the AUC of other hormones and metabolites (i.e. growth hormone, steroids, and a host pancreatic incretin hormones) and their concentrations in the all-important portal circulation (blood flow inside the belly between the gut and liver — not measured by blood from the arm) are all important in the equation. These hormones are involved in fat and carbohydrate metabolism, and their roles are still being elucidated. This is where a lot of the confusion regarding other dietary food stuffs (i.e. sugar alcohols, grain alcohol, mixed meals) lies.

GI and GL are similar concepts in the context of carbohydrate-restricted diets: low GL intakes are in fact low GI... even if a small amount of a high GI food is consumed. (Imagine a teaspoon of sugar in your coffee; it is a relatively high GI food, but its GL content is almost trivial for most active people with an intact pancreas.) In contrast, a large meal of low GI food can have a huge GL. The blood sugar may never get very high, but the AUC can be very large, and the impacts on encouraging fat storage profound.

Based on my understanding of the current scientific literature, the GL best reflects the potential of a meal to either contribute or detract from body fat stores (the most important end point for most people engaged in a carbohydrate-aware lifestyle). I anticipate that this generalization will become further fine-tuned as more data is generated about the effects of particular dietary components and carbohydrate-like substances. [for example, see the hot-off-the-press article: Resistant Starch Consumption Promotes Lipid Oxidation by Higgins JA, Higbee DR, Donahoo WT, Brown IL, Bell ML, Bessesen D in Nutrition & Metabolism 2004, 1:8 (6 October 2004)]

On a practical level, GI of meals is variable from person to person, varies dramatically with meal composition, and is impractical to calculate by the vast majority of people. In contrast, GL is much easier to estimate by simple rules of thumb (i.e. total carbohydrate grams minus fiber), hence is actually doable in real life. I am following this issue very closely for the Carbohydrate Awareness Council, and I look forward to keeping Low Carb Luxury updated with the progress of this issue as the scientific literature evolves.

                                     

From Fred Pescatore, M.D.
The Centers For Integrative and Complementary Medicine
Author of The Hamptons Diet

The Glycemic index has some value but it is not a definitive guide to anything. Just because we think we know how well or poorly something is metabolized by the body, does not mean it has any effect other than to add calories to our diet. Let's keep in mind that ice cream has a glycemic index of 35 only slightly higher than maltitol, but no one would consider ice cream to be a healthy food.

There are multiple things to consider in a glycemic index of a food, including the fat content which slows down absorption. So, while the GI may be a decent indicator of the "healthiness" of a certain food, it is too simplistic to be used as a definitive guide. Also, I am not convinced that there is any standardization of the technique used to determine a food's GI and there is no scientific evidence to support its use in dieters, diabetics or the like.

Bottom line: use it as a guide, but not as a bible.

From Pete Maletto
Chief Science Officer
DynaPure Nutrition

I think the glycemic index has and always will hold great value in the nutritional industry, for people using carbohydrates as strategic alliance to athletic training. Unfortunately, one of the many problems I can see with this is the complexity involved in formulating the correct glycemic value for the food and the individual digestive responses which vary greatly from person to person.

Take for instance fructose, which has a very low glycemic value (26). Fructose must first rely on the liver to convert it to glucose, so even though it's a 100% carbohydrate sugar, it's low glycemic. I have to doubt that Doctor Atkins would endorse this method, as it can be quite confusing and still introduce more carbohydrates into the consumer's diet. Of course, it would make for cheaper food which is great if you're a manufacturer, but hey low carb food IS low glycemic.

The other issue is that Atkins has developed its own patent pending method of testing, which seems like a conflict of interest to me for sure. As another example, the glycemic index of fat free mashed potatoes is a high 88, but if you put a pat of butter on it the fat lowers the glycemic index to a paltry 55, and if you add a steak then the total glycemic index for the meal would be around 40 from the added protein. Not too bad if you like carbs, but hey the Glycemic Index would be low. Now we will have more discrepancies in label macronutrient count because of the confusion caused by another variable.


From Joy Pape, RN BSN CDE WOCN
Certified Diabetes Nurse Educator

The glycemic index does have value in meal planning for people who have diabetes. I know this by the response of my patients as well as some of the studies that have proved this. I have several patients who are more concerned with the glycemic index of foods than the actual carb count who have done very well. They choose lower glycemic index foods for their choices and have better glucose control as well as many that have needed to lose weight have.

In the past the American Diabetes Association (ADA) did not recommend the use of the Glycemic Index because most people do not eat one food alone, but rather mixed meals. My understanding is that the ADA is changing their recommendation, soon to be out. I agree, most people do eat mixed meals, but when the mix is chosen from lower glycemic foods, I have, for the most part seen only improvements.