The carbohydrates we consume are combinations of sugars. Simple carbohydrates consist of one or two strands of carbon atoms (which are sugar molecules) and include honey, fructose (the sugar in fruits), sucrose (table sugar), lactose (the sugar in milk) and corn syrup. Complex carbohydrates consist of three or more sugar molecules and include grain products, crackers, bread, potatoes, corn, rice, and pasta.

When we consume carbohydrates there is digestion in the intestine with conversion from simple or complex carbohydrate to glucose (a simple sugar). Glucose is the only form of carbohydrate usable by the body and all carbohydrates are converted and absorbed in this form.

When carbohydrates are eaten the blood glucose (sugar) rises stimulating secretion of insulin by the pancreas. Insulin causes the transfer of some of the glucose into tissues and then initiates the process of converting the remaining glucose into fat.

Some carbohydrates when eaten are converted faster to glucose than others. These cause a more rapid rise in the blood glucose and a corresponding more rapid release of insulin. The blood glucose drops quickly in response to the insulin output and we become hungry again. This often leads us to again eat the same carbohydrate endlessly repeating the cycle. These fast converting carbohydrates are called high glycemic.

It is not obvious which carbohydrates are low and which are high glycemic. For instance potatoes, a complex carbohydrate, have a higher glycemic index than table sugar! Each food has to be tested for its behavior. The testing results in a Glycemic Index Table in which all carbohydrates are compared to an arbitrary standard such as potatoes or white bread. Rice Cakes are frequently eaten by dieters but they are very high glycemic. They are low in calorie content but tend to result in hunger leading to more food intake.

Consider the following summary of a study reported in the medical journal Pediatrics in 1999:.

Twelve obese teenage boys were evaluated on three separate occasions. During each evaluation, subjects consumed identical test meals at breakfast and lunch that had a low, medium, or high glycemic index.

The high and medium glycemic index meals were designed to have similar percentage of fat, carbohydrate, and protein, fiber content, and palatability. All meals for each subject had equal calorie content. The amount of food intake was determined in the 5-hour period following lunch.

Voluntary food intake after the high-glycemic index meal was 53% greater than after the medium-glycemic index meal, and 81% greater than after the low-glycemic index meal. In addition, the high-glycemic index meal resulted in higher serum insulin levels, and adversely effected a number of other metabolic parameters being measured.

The rapid absorption of glucose after consumption of high-glycemic index meals induces a sequence of hormonal and metabolic changes that promote excessive food intake in obese subjects. Additional studies are needed to examine the relationship between dietary glycemic index and long-term body weight regulation.

A prevailing opinion is that repeated glucose-insulin spikes from high glycemic meals results in tissues that fail to respond to the effects of insulin (insulin resistance). This is thought to be a major cause of adult onset diabetes.

High glycemic does not mean that the particular food is bad, however, iIt does have particular characteristics which you should be aware of. By combining high glycemic foods with protein or fat, the absorption characteristics are changed markedly and the mixture is no longer high glycemic. Putting sour cream or butter on potato significantly changes the high glycemic nature of the potato.

Remember a high glycemic index is assigned to foods that cause a rapid rise in blood sugar and leads to a correspondingly rapid rise in insulin levels. This may result in a low blood sugar level sometimes with unpleasant symptoms such as anxiety, shakiness, lightheadedness, and hunger.

For more on the Glycemic Index go to:
http://www.mendosa.com/gi.htm

For a list of foods and their glycemic index go to:
http://www.mendosa.com/gilists.htm