The Glycemic Index - Your Weight and Your Health

From - Rouge Valley Health System - Cardiac Rehabilitation Services - Toronto, Ontario
August 2003
By: Maria Ricupero, R.D.

Obesity is a known risk factor for health. Weight loss can help lower cholesterol and blood pressure, and control blood sugars for people living with diabetes. You don't have to get to your "ideal" weight to be "healthy." Working toward achieving a healthier/lower weight is what matters. There's a big difference.

Several studies show that losing 5-10% of your current weight is associated with improving overall health and lowering your risk of certain diseases. Eating right and exercising regularly will help you get closer to your weight loss goals.

People are always looking for the latest trends in diets. We know about and maybe have even tried the "grapefruit diet", the famous (or infamous) "low carb, high protein diets", "the Bernstein diet", and so on.

More recently, there has been a lot of talk about the "glycemic index" (GI) and it's role in weight loss. The truth of the matter is that this is nothing new. The glycemic index has been studied for years, but until recently, more people have been interested in its role for managing diabetes, cholesterol and now, weight loss.

So what is the glycemic index (GI) anyway?
The glycemic index is a rating scale. It ranks carbohydrate foods (like potatoes, rice, noodles, pasta, bread, etc.) by how much they raise your blood sugar. The ranking of foods is compared to a standard, which is usually glucose. Glucose is rated at 100 on the GI scale. Foods that have a GI rating of over 70 are considered high, while moderate GI is 40-70, and low GI less than 40.

Foods that are high on the glycemic index are considered fast-acting carbohydrates. Typically, highly refined or processed foods have a very high GI rating, like instant mashed potatoes or instant noodles, canned pasta, etc.. Most of the nutrients have been stripped from these foods as a result of processing. It's almost as if digestion has occurred even before the food has gotten into your body. The grains are very fine. Typically, the more wholesome and fibrous the food, the lower the glycemic index. Examples include, legumes (chickpeas, kidney beans, lentils), pasta and whole grain cereals.

So, why is all this important and how does this relate to weight loss?
Foods that are digested and absorbed quickly by the body are known to be high on the GI scale. These foods cause blood sugars to rise and fall quickly. A low blood sugar often triggers signs/symptoms of hunger. You might find that eating high GI foods stimulates hunger sooner. And, that means you may be tempted to eat more. Eating more means taking in extra calories that you otherwise could have done without.

Foods that take longer to digest (ex. high fibre foods) stay with you longer and increase satiety. These foods are low on the GI scale and prevent your blood sugar from spiking. In this way, it also helps to control and regulate blood sugar levels in people with diabetes.

In my practice, I often hear my clients complain that they feel hungry approximately 2-3 hours after they have eaten breakfast. When I probe and ask them about what they are eating, often they will tell me they are having cold cereal. Most cold cereals, like cornflakes rank very high on the GI scale. Although a healthy choice, cold cereals are processed. It takes very little effort for your body to digest and break down cold cereal. So it doesn't surprise me when my clients complain that they are not satisfied.

I will often recommend switching to a high fibre cereal, such as All Bran buds, Optimum, 100% All Bran sticks or oatmeal that are typically low on the GI scale. The high fibre content not only satisfies your hunger, (which may help with weight loss,) but it can also assist in lowering cholesterol and improving blood sugar control. It's a win-win situation!

Although the glycemic index can provide us with a better understanding of certain foods, it should not be looked at as yet another fad diet. There is no magic bullet out there. The key to weight loss and managing your health is to make better food choices. Avoid fast food restaurants. Don't include ready-prepared, processed or refined food products in your diet. Emphasize and include vegetables every day. Good eating habits must be accompanied by regular exercise for overall health and fitness.

For years, dietitians have been promoting and encouraging people to include more wholesome and fibrous foods in their diet. Typically these foods rank low on the GI scale, so choose them more often. The message hasn't changed. Now there's just a fancier title for it.

The table below outlines some examples of foods that are high, moderate and low on the GI scale:

Food High GI Value (70-100)
Baguette, French 95
Rice cakes 82
White bread 70
Corn flakes 84
Potato, white-skinned, baked 85
Food Moderate GI Value (40-70)
Oatmeal 45
All-Bran buds with psyllium 45
Banana 55
Spaghetti, white 41
Rice, brown 55
Chickpeas, canned 42
Food Low GI Value (< 40)
Barley 25
Milk, skim 32
Yogurt, flavoured, low fat 33
Apple 38
Soybeans 18

Foster-Powell, K and J. Brand Miller. "International tables of glycemic index," Amer J of Clin Nut 1995;62:871S-893S.

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