Glycemic Index


Hi, I was wondering if you've heard of the glycemic index. If so, how credible is it? I find it really hard to stay away from seemingly healthy foods, like carrots, potatoes and from low fat snacks like rice cakes and Honey Nut Cheerios. All these foods I have named above are considered "unacceptable". I am not a diabetic, but I am trying to lose 8 pounds the healthy way.

The glycemic index is a measurement of the effect a food has on your blood sugar level. Some foods, which have a high amount of sugar in them such as, maple syrup, honey and candy, as well as, foods, which are "starchy" such as those, you mentioned - carrots, potatoes and cheerios are rated high on the gycemic index. They are rated this way because when you eat these foods you will experience a rapid rise in your blood sugar level.

Other foods, especially foods high in fiber such as, whole-grain rye bread and All-Bran cereal are rated low on the Glycemic Index because they do not produce a rapid rise in blood sugar after eating them.

The purpose of the glycemic index is for diabetics who need to be concerned about their blood sugar levels on a daily basis and athletes who need to restore their blood sugar levels after an athletic performance. The glycemic index is not a good way to lose weight. For weight control it is important to use the Food Guide Pyramid. You should concentrate on having a diet with a foundation in the grains, breads and cereals group (six - eleven servings each day), five or more servings from the fruits and vegetables group, two servings from the milk group and two servings from the meat group. Good luck with your diet.


I am an ACSM and ACE Certified Personal Trainer. I've been in the business for about 10 years now and one of my missions has always been to help dispel the fads and myths about health and fitness. I have been reading your FAQs for some time now and would like to thank you for an outstanding contribution to the health education of our society. I enjoy reading your website and greatly appreciate the information that you make available to us all.

(I also want to tell you that I admire your patience and lack of defensiveness when answering questions from people who sound as though they are trying to educate you, instead of visa-versa!)

My question is about the relationship of insulin to sugar and refined grains. It is my understanding that when we eat a lot of sugar at once, we induce the release of large quantities of insulin. This large insulin release causes the cells to take up large, unregulated quantities of sugar from the blood and actually leaves us with a low blood sugar level in the end. This gives us the tired feeling- loss of energy which is due to the "sugar crash" which comes after the very temporary "sugar high" that we get from eating the sugary foods. My few questions are based on the assumption that the above is correct.

1.) I read somewhere when eating fats with large amounts of sugar, the fats will be absorbed into the cells quicker, due to increased levels of insulin. What do you say about that?

2.) I have heard the claim that eating refined grains, (i.e. white rice, white breads, etc.) will cause the same "energy low" due to the speedy breakdown of the refined grain into sugars in the digestive system - (causing a high blood sugar level, causing increased insulin levels, causing quick sugar uptake into the system, leaving the body with low blood sugar and that tired feeling again). Is this true?

3.) Regardless if the above sugar-effects are correct, I am aware of the nutrient benefits of whole grain foods and encourage my clients to eat them. However, many of my clients tell me that they have compared calories in whole grain breads to calories in white breads and the whole grains have much more calories so they don't want to eat them! Is this increased caloric content due to the fiber? Is fiber counted when measuring calories of a product? If so, fiber isn't absorbed, so I'd think that the calories of fiber really don't matter.

I'd really appreciate any response. I have been trying to find the answers to these questions for quite some time now! Much Thanks.

Your basic assumption about the insulin response to foods is called the glycemic index. What that means is depending on the carbohydrate you eat, your blood sugar can go up very little or a lot. Typically though meals consist of several carbohydrates i.e. milk, bread, fruit, vegetables as well as desserts or sweets which can cause either a varied (from individual to individual) or accumulative increase in blood sugar.

All carbohydrates are made up of sugars. The body is going to break carbohydrates down into simple sugars (glucose, fructose or galactose) whether the carbohydrate is refined grains such as white rice or white bread or a more complex carbohydrate like starches or dextrins. The end product will always be the same - glucose. The difference is the carbohydrate in starches like breads is 100% available for conversion into glucose. Whereas other sources of carbohydrate like fruits are only 50% available. Therefore, some carbohydrates have a higher "glycemic" effect on blood sugar than others.

Some "diet" plans are built around the principle that carbohydrates with a high glycemic index should be avoided. While this may make sense for uncontrolled or insulin dependent diabetics, it doesn't make sense for the person with adequate insulin who just wants to lose weight. Avoidance of foods with a high glycemic index not only cuts out foods with valuable vitamins and minerals, it does not increase weight loss.

1. When you eat a lot of fat with a lot of sugar, you are eating a lot of calories, probably more than your body can use right at that moment. These excess calories will end up as fatty acids or glucose in your blood. When there is an excess of fatty acids in your blood, your body will keep some fat in your blood and store the rest in fat cells. Your liver also clears fats from your blood either by turning fats into bile that is stored in the gall bladder or cholesterol (LDL) and triglycerides (HDL and VLDL).

Insulin does increase fat storage when glucose is in excess and thereby enhances the storage of fat, but insulin doesn't contribute the largest source of blood fats, which is from food fat. We know that the best way to reduce blood fats is to restrict saturated fat and total fat in the diet. Insulin dependent diabetic's often gain weight because they have higher insulin levels in their blood and poor insulin receptors on cells. So diabetics need more insulin to move glucose out of the blood and into cells to be metabolized. Also, the injected insulin can't be "turned off" by the body and continues to work on clearing glucose from the blood. Therefore, a diabetic needs a precise balance between the amount of carbohydrate they eat and the amount of insulin they take. Too much of either results in weight gain when insulin levels are increased to take care of high blood sugars.

To conclude that because insulin is secreted to metabolize glucose which result produces some fat that you need to restrict carbohydrates because they increase blood glucose and thereby stimulate the release of insulin is faulty logic. Insulin is produced in response to even small increases in blood glucose above fasting levels. Furthermore, insulin levels decrease as carbohydrate is cleared from the blood. The real problem is too many calories which increases fat storage.

2. An elevated blood sugar can numb a person and make them sleepy which is the reverse of the sugar high you describe. When your blood sugar (glucose) goes up, your body responds by making insulin to remove glucose from your blood and move it into cells to be metabolized. As the blood sugar drops to near normal, your body responds by making glucagon which causes the release of glycogen (stored glucose) from your liver to prevent your blood glucose from dropping even lower where you could pass out. It is your body's balance between these two hormones that regulates your blood glucose. If you have normal insulin and glucagon secretion, then you should not experience "low energy" just because your blood sugar comes back down to fasting levels. If your blood sugar drops more than 15% below your fasting level, you may feel "sugar crash" or other symptoms of hypoglycemia.

3. Dietary fiber is the foodstuff that is not digested by the stomach or small intestine. There are two kinds of fiber, insoluble and soluble. Insoluble are the foodstuff that is not dissolved by water or metabolized by bacteria in the large intestine, examples are cellulose, hemicellulose and lignin. Soluble fiber is dissolved in water and metabolized by the bacteria in the large intestine, examples are pectins, gums and mucilages. The soluble fiber is metabolized into short chain fatty acids and gases. These are absorbed into the blood. Soluble fiber yields about 3 kilocalories/gram. Whole grains contain the entire seed of the plant, which includes the bran, germ and endosperm. Whole grains are an example of insoluble fiber. Since insoluble fiber isn't broken down in the body, it doesn't yield any calories. But since you eat a diet of soluble fiber and insoluble fiber, you cannot conclude that fiber contains no calories.

I would continue to encourage people to consume foods high in dietary fiber. These foods help in weight control and reduce the risk of obesity. The foods high in fiber fill us up and don't yield much energy. Foods high in fat do the opposite. There are more potential benefits to fiber such as the reduction of the risk of colon cancer and a lowered blood cholesterol level, but these topics are still being researched.


Thanks so much for your prompt and detailed response regarding my question about a low carbohydrate diet. I very much appreciate your professional opinion because I don't want to do anything harmful. Just so you know, when I said I "had trouble" with a low calorie diet, I simply meant I had trouble staying on it because I felt hungry most of the time. Again, I appreciate your help very much.

You're welcome. Did you try the Healthy Body Calculator? It will calculate calories based on different weight goals including 1 - 2 pound weight loss or weight maintenance. Use that as a guide to planning meal.

If you have trouble staying on a low calorie diet like 1200, perhaps, you should try a slightly higher calorie level that still will achieve slower weight loss. You may not lose as fast, but you may be more likely to stay on your weight loss program. Also remember to include exercise.