The glycemic index measures how quickly sugars and starches in foods get converted into the simple sugar glucose and cause a rise in blood sugar. It is measured on a scale of 0-100, with pure glucose being set as the standard for 100. Foods with no carbohydrate content, such as most meats, are a 0 on the scale. Since fluctuations in blood sugar are linked to fat storage in the body, diets based on the glycemic index help dieters shed pounds.
Basics
Most foods break down in the body into sugars, which are then sent into the bloodstream to be utilized by the body as energy or stored as fat. Some foods enter the bloodstream very quickly, with pure glucose being the quickest to hit the bloodstream. Other more complex foods take a longer time to break down, so they enter the bloodstream slowly, causing blood sugar levels to gradually increase instead of shooting up. The slower the rise in sugar levels, the less likely the body is to produce spikes of insulin, a hormone that signals the body to store energy as fat.
Numbers
The glycemic index of foods is given in numbers and also as a rating of high, medium or low. A high glycemic index food is considered to have a glycemic index of 70 or higher. A medium glycemic index number is between 55 to 70. Low glycemic index foods are those with a glycemic index under 55. Pure glucose is the reference point, set at 100 on the scale.
Insulin and Low Glycemic Index
Foods with a low glycemic index take a long time to break down and therefore cause blood sugar to rise slowly. Insulin levels react slowly to these foods. A diet consisting primarily of low and medium glycemic foods lowers overall blood sugar and makes the body burn fat to use as energy, since having low blood sugar levels sends a signal to the body that it needs more energy.
Insulin and High Glycemic Index
High glycemic index foods are more like pure glucose. These foods boost sugar quickly in the blood and cause the body to respond by producing lots of insulin quickly in response. The body reacts to high insulin levels by storing more fat, since it sees this as an indication that there is plenty of energy available in the body. Eating lots of high glycemic foods causes the body to store pounds and leads to weight gain. Over time, the insulin response can even wear down and stop working, leading to diabetes.
Types of Low Glycemic Foods
Low glycemic index foods usually have little to no carbohydrates. Proteins and fats don't even appear on the glycemic index because they have no carbohydrates to raise blood sugar levels. Of foods containing carbohydrates, those with high fiber, such as most vegetables, fruits and some whole grains, are considered best. Pasta has a lower glycemic index than many other types of grain products because of the processing method. Diets based on the glycemic index encourage eating a lot of meat and complex carbohydrates under the idea that these foods will encourage the body's natural fat-burning processes by maintaining low blood sugar levels.
Types of High Glycemic Foods
Aside from table sugar, other high glycemic index foods include white bread, candy, bakery products and sodas. Some surprising foods that have a high glycemic index are breakfast cereals, watermelon and potatoes. Since eating these foods will cause a spike in blood sugar leading to weight gain, eating them is discouraged.
