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CakeNutrition’s Feature Article Friday – The Glycemic Index

December 16, 2011

The Glycemic Index: The Old, the New, and Why it Affects YOU

The Glycemic Index has been around for a while now (in fact since the early 1980’s ). For those unfamiliar with the glycemic index (GI). It ranks foods – mainly carbohydrates – depending on how each affects your blood sugar.  Since the GI’s first exposure there has been confusion at ALL levels of society as to its actual application in the daily diet. Models and TV stars have proclaimed LOW GI foods are best because they think it helps keep a low body fat. Gym rats have declared that HIGH GI foods are better because they are supposed to build most muscle. Even on the scientific end there is confusion; studies have “proven” how either HIGH or LOW GI diets have profound effects on health  parameters (like risks for diabetes, heart disease, and even certain cancers) weight maintenance, and sports performance. . . and I’m sure you’re all aware of my biased towards scientific findings over word of mouth advice. But on the topic of GI, even this “proof” in some studies has been countered by other studies “proving” the exact opposite!! How can we apply the GI to help our health and fitness goals if there are so many conflicting pieces of evidence? The answer may lie in the inherent weakness of the GI as a way to assess an entire diet. But there is still hope! The newer concept of “Glycemic Load” has not only helped to clarify the GI situation but has also shown specific and unique effects on many individual concerns like disease risk, weight management and sports performance.

To understand the GI, you first need to understand a little about carbohydrate metabolism

When you eat carbohydrate foods – like breads, cereals, and fruits – your body digests them, breaking them down into smaller, easy to use, sugars. These sugars are then transported into your cells via the blood stream (blood sugar). Your cells can then use these sugars for several purposes including immediate energy use, storage for later energy use, and even as building blocks for other important functions.

*For an in-depth understanding of carbohydrate metabolism and regulation, read my [link]Overview of Carbohydrate Biochemistry[/link] – Article soon to come

So, you eat carbs, the body turns them into small sugars and uses blood to move them around. But what exactly is the Glycemic Index?

                The Glycemic Index (GI) is a way to rank single foods depending on the increase in blood sugar after eating them. High glycemic index foods (GI>70) raise blood glucose sharply, but levels decrease quickly as well. Examples would be white bread, bagels, chips, pineapples and many candies.  On the other hand, low glycemic index foods (GI < 55) provide a steady blood glucose level for a longer period of time. Examples of these would include whole wheat breads, oatmeal, pasta, sweet potatoes, most green, leafy vegetables and legumes. For a comprehensive list of GI values for common foods visit http://www.diabetes-guide.org/glycemic-list.PDF

So What is the Difference Between the Numbers of the GI?

This is something that confused me for a bit. What really helped me to understand the GI better, was putting foods into GI categories, rather than thinking about them as having an individual GI number.

3 Categories of the Glycemic Index

HIGH GI = Foods with a GI rating over 70

MID GI = Food with a GI rating between 55-70

LOW GI = Foods with a GI rating below 55

 

So for example, I don’t care that “Food X” has a GI of 77, and “Food Y” has a GI of 85, but rather I simply consider both Food X and Y to have a HIGH GI.

*Want to Learn More about the GI? Visit my in-depth article on [link]Carbohydrate Structure and Its Effect on the GI[/link] – Article soon to come

What’s Causing All the Confusion?

                I believe a reason stems from the innate downfalls of the GI. For one, the glycemic index does NOT take into account the AMOUNT of any food you eat. For example, let’s consider eating a single skittle. Because of its GI of nearly 100, we consider it a HIGH GI food. In this category, we believe it will cause a sharp increase in blood sugar. However, in reality because we are just eating a single skittle, it won’t even make your blood sugar budge. On that same note, if you decide to eat AN ENTIRE loaf of LOW GI, whole-wheat bread, your blood sugar will shoot through the roof! The GI has a clear inability to factor in the amount of food consumed. Also, the GI only considers the blood sugar effects of individual foods, and cannot be converted into whole meals. For the GI to be properly used to judge a diet, each item in any meal would have to be fully digested before the next food is eaten. When is the last time you ate your mashed potatoes, then waited 3 hours to fully digest it before eating  your steak, and then waited another 3 hours before drinking your soda? Probably never.

Solution: The Glycemic Load

                The glycemic load uses a simple equation to account of nearly all the problems of basing a diet using the GI by itself. In particular, it accounts for the amount of food eaten along with the foods GI ranking. Beyond that, it is able to account for consumption of different foods in a whole meal. Recent studies have proven (and been verified) that glycemic load modulation can have a profound effect on weight management (specifically body fat and waist size), cholesterol levels, triglycerides, and sports performance and muscle growth just to name a few. I will be discussing each of these benefits in subsequent articles so keep an eye open for them!

So … You’re Saying NOT to Use the GI???

                No, no, not at all. The GI is an AMAZING tool to help with your health and fitness goals and is necessary for utilizing glycemic load. But, I do want to stress that changing the GI of your diet alone may not provide the benefits you are looking for. By considering the Glycemic Load of the diet, rather than just the Glycemic Index we can accomplish direct goals such as:

-Working desserts into a weight loss diet

-Optimizing sports performance without feeling bloated

-Controlling blood sugar and diabetes risk without giving up favorite foods

-Maintaining energy levels throughout the day (avoiding that 2 pm crash *cough cough*)

Awesome – So What Do We Want? High GI? High GL? Low GI? Low GL?

Unfortunately, there is no one single answer. Modulation of the glycemic values in your diet has to be custom fit to your own personal goals. For example, athletes looking to refuel their muscle will want frequent high GL meals, whereas diabetics wanting to control blood sugar will want low GL meals. The goal of this article was to provide a general overview of the applications of glycemic index and glycemic load.

Piece of Cake … Nutrition:

-Glycemic Index (GI) ranks single foods on how they affect your blood sugar

*High GI >70, Low GI <55

-Glycemic Load (GL) describes how a meal will affect your blood sugar

-No matter what your goal, utilizing GI and GL can help you optimize results!

-Different goals require different changes in GI and GL – check in for future articles on the topic!

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