Glycemic Index: A Closer Look

You’ve probably heard the term “Glycemic Index Factor” popularized by the book, The New Glucose Revolution – Life Plan by Jennie Brand-Miller, PhD. This is not another shift your body’s chemistry and presto the pounds fall off diet like, for instance, the “Grapefruit Diet” which allows you to predominately eat one type of food – yes, grapefruit and theoretically you can lose weight. Obviously it is difficult to stick to and it is not very nutritionally balanced. This book describes more than just a weight loss plan it outlines a life plan to help in the management of chronic, degenerative diseases.

This book was a valuable resource for me to suggest to my patients to read to gain some insight into my clinical approach.

We’ve all heard the term Glycemic Index Factor (GIF) but what is it really and what are its clinical applications for managing chronic, degenerative diseases?

As the term GIF does not contain the word diet, it is not a diet. It is a way to measure foods’ carbohydrate content. Any food that contains carbohydrates has to some degree, a physiologic effect on blood sugar levels, BG, insulin and ultimately fat storage. Understanding and using the GIF can help us decrease our sugar intake with knowledgeable choices which leads to better BG numbers and overall body composition. Overall, better body composition; less fat and improved lean tissue contributes greatly to better metabolic numbers. – Some of those important numbers impacted are cholesterol, triglycerides, LDLs and HDLs, insulin and HbA1c.

We can design a food intake regime that creates lower, steadier, blood glucose levels throughout the day. From a clinical standpoint we know this is useful in managing DMII (diabetes type 2) and all metabolic diseases in general; insulin resistance, hypoglycemia, GI disorders, migraines, joint pain and general inflammation can benefit from better, lower levels.

There also can be weight loss.

The GIF was originally developed in 1981 by diabetes researchers to study blood sugar levels and potential ways to control these levels. Researchers wanted to measure the ability that they knew different foods had to raise blood sugar levels which is referred to as a “glycemic response”. The higher the response or rise in blood sugar levels that a food elicits the greater insulin response occurs from the pancreas. All foods were categorized based on their ability to raise insulin levels into high, moderate and low GIF response categories.

All foods are based on or compared to pure table sugar (glucose). This has the highest, single index of (100). Let’s compare similar low, moderate and high index food values. Higher value foods are definitely to be eaten in smaller amounts due to their ability to quickly raise blood sugar levels and their generally higher calorie values. High GIF values foods are typically above an index of 70 like; parsnips (97), red baked potatoes (93), dates (97), Cheerios (106), cornflakes (119), pretzels (116), waffles (109).

Now, how can so many foods have index values above 100, pure sugar? These very processed foods notably cereals that are so refined they almost “melt” into your mouth and into your blood for that matter without much digestion process needed. The GI has brought these starches more to the fore front and the wallop that it packs on the glycemic response. As pointed out, the digestion of starches is rapid because it starts in the mouth via the enzyme, amylase as opposed to most other foods which start their digestion primarily in the stomach. This double whammy; starches being very processed and allowing its very fast break down and digestion will exceed an index of 100.

Though many of the cereal items appear to be a grain product they have been so mechanized that they are now the consistency of pure starches which are equivalent or above that of sugar in their GIF classification as they are so refined. And, more importantly in the rapid and intense impact they have on BG as we see. When eating these starches that are also almost always combined with sugars – the blood sugar levels then become quickly high and the response is great,100 plus. And these high responses, “spikes” are what precipitates the following effect of BG lows, “crashes” as seen with hypoglycemia.

Other foods similar to these are; white bread, crackers and chips. All of these are highly processed, come in a box and are very far from a whole food.

Unprocessed, whole foods contain more fiber and protein and provoke a lower GIF response – the digestion has to “work” a bit more and the specific enzymes need adequate time to work – that is what it was designed to do and makes for a healthier Gastro intestinal environment and also slows the digestion of any of the carbohydrates in the foods or meal as well.

Moderate value foods are typically between 50-70.Some of these are; sweet corn (56), yams (54), pineapple (66), Special-K (54). I picked these foods to compare because of the similar foods that we compared in the high index category. The difference from the higher category in their glycemic response is largely due to the lowered starch and sugar content and higher fiber content of these moderate foods.

These are some of the lower ranked foods and are below 50, some may be surprising; black beans (43), chickpeas (47), apples (54), grapefruit (36) and rice bran (27). The beans, peas, fruits and whole grains have gotten reputations as “no-no” foods with low carbohydrate diets but they are “slow burning” healthful, carbohydrates. Their glycemic responses are very low due to their very high fiber makeup and protein contents as in the case of especially the beans. When eaten in the right amounts, over time, can create a healthful decrease in weight with better body composition. You can also put almost every green leafy vegetable in this low category.

We just can’t get around it — we’re just going to have to start eating better.

Lower rises in blood sugar elicits a lower rise in insulin which allows less fat storage and sugar highs and the sugar crashes. This is what we want! Also spikes in insulin create hunger pangs and make us want to eat more – it’s a bad cycle. We want to keep these to a minimum especially when we’re restricting our food intake. So, higher protein and fiber foods creates a slower energy/calorie burn that keeps us going on a steadier basis with more normal BG levels and weight loss will follow.

We know that increased adipose tissue (fat) creates a cascade for Metabolic Syndrome and longevity. But diets don’t work – We need to educate on how to completely adopt healthful eating practices. The Glycemic Index when followed can foster a sound guide to intake. It is the basis of most current weight loss diet plans today.