Glycemic Index

A viable method for measuring a person's body size according to their fat mass is the Glycemic Index to give a clear indication of person's body weight status.

It helps to determine if a person is overweight, obese, at their correct weight or underweight. The result can help a person such as a parent or doctor to decide on a suitable course of action regarding their diet, fitness level and lifestyle.

What is the Glycemic Index?

Three major food groups are fats, carbohydrates, and proteins. The Glycemic Index, also known as glycaemic or GI, is a measure of the effect carbohydrates have on blood sugar levels.

The Index ranges from high to low. Carbohydrates that are rapidly broken down during digestion and releasing glucose into bloodstream quickly are considered to have a high GI.

On the other side, carbohydrates that take longer to break down and release glucose slowly into the bloodstream are considered to have a lower GI.

How Did the GI Come About?

Dr. David J. Jenkins and his colleagues from the University of Toronto developed the GI concept in 1980-81.

They were conducting research to determine which foods are best for people with diabetes. Jenkins was able, by categorizing carbohydrates into an Index, to determine which foods were more diabetic-friendly and which weren't.

What Are the Indicators?

The best use of the index is in ascertaining where on a fixed scale a person's weight with regard their height lies.

A high GI indicates a rapid elevation in blood sugar levels along with a similar high insulin demand.

Low GI indicates slower body absorption of carbohydrates. This could also mean that the liver and peripherals are more efficient in extracting carbohydrate products.

A lower glycemic response is important for diabetics. It usually indicates a lower demand for insulin (although this may not be true in all cases).

This could help improve long-term glucose control as well as blood lipids. The insulin index is a direct method of measuring insulin response to certain foods.


The definition of a food's GI is the area below the 2 hour AUC (blood sugar response curve). This is obtained after consuming a fixed amount (typically 50 g) carbohydrate.

The AUC for the food being tested can then be divided by the AUC of a standard. This standard can be either pure glucose or white bread.

This yields two definitions. The total is multiplied with 100 and the average GI value can then be calculated using data taken from ten human subjects.

Each food is is given a relative ranking according to its test results. The reference food is glucose, which is allocated a GI of 100.

This creates a universal standard for accuracy in results. White bread has a GI of 100 as well.


This sums up what the Glycemic Index is and how it is used.

Using this standard is a measurable way to determine if a person is the right size, overweight, obese, or vice versa and is a helpful measure when choosing a diet or fitness plan.

Consult your doctor if you have concerns about your physical size or need to know more about your health.