Updated: Dec 17, 2019
The glycemic index (G.I.) is a way of ranking carbohydrate foods relative to how they affect the blood sugar. The American Diabetes Association recommends that choosing low glycemic foods be part of the menu plan recommendations for those with diabetes. Stabilizing the blood sugar with a low glycemic index diet is also good for those trying to lose weight as blood sugar spikes and dips can increase hunger and a low glycemic index (g.i.) can help control that.
Three Classifications for G.I.
To put the G.I. into practice, one needs to know the cut-offs for the different foods and how they affect the blood sugar. We want to avoid those foods with a high glycemic index and concentrate on choosing those carbohydrates with a low glycemic index.
Low: 55 or less
The cut-offs for foods are a little different than for the whole day. To calculate the g.i. for a meal we use the following cut-offs:
Low: 45 or less
Point: We need to aim for a diet with a g.i. of 45 or less.
Examples of Low Glycemic Index Foods
Low: Green vegetables, most fruits, raw carrots, kidney beans, chickpeas, lentils and bran breakfast cereals
Medium: Sweet corn, bananas, raw pineapple, raisins, oat breakfast cereals, and multigrain, oat bran or rye bread
High: White rice, white bread and potatoes
What Affects the G.I. Value?
The g.i. value can be manipulated by several variables such as:
How Refined the Carbohydrate is
High fiber foods lower the g.i. of a food. Thus, a whole apple has a lower glycemic index than applesauce. Or, adding a fiber supplement to a meal can lower the g.i. of the entire meal.
Chemical Structure of the Carbohydrate
The body cannot metabolize fructose very well thus it has a lower g.i. than glucose. Glucose has a g.i. of 100 but sugar, a mixture of glucose and fructose, has a g.i. of 65
Physical Structure of the Carbohydrate
The starchy particle size and size of the carbohydrate molecule make a difference in the glycemic index of the food product. Most breads, for example, are high g.i. because of fine particle size and the expansive area for digestive enzymes to work quickly in breaking down the starch to form blood sugar.
Ripeness makes the g.i. go up.
How Carbohydrates are Cooked or Prepared
Cooking pasta less lowers the g.i. by making it resistant to digestive enzymes. Thus, cooking can make a difference. Pasta normally has a g.i. of 40-50. This can be lowered by cooking it al dente or cooking it less.
Fiber Slows Down the Digestion
As mentioned earlier, fiber can lower the g.i. of a food by protecting it from digestion from enzymes or prolonging transit in the intestinal tract.
Fat and/or Acid Slows Down Digestion/Meal Composition
The presence of fat or acid will slow the emptying from the stomach and lower the g.i. of a food. Adding vinegar, lemon juice or pickles to lower the g.i. of a meal is effective at doing so. Just take care if you have a hiatal hernia or GERD as this can cause gastric reflux and a subsequent burning in the esophagus.
Taken alone fat or acid will not affect the g.i. but taken as part of a meal it will have an effect. Protein stimulates insulin which lowers blood sugar and fat slows down gastrointestinal emptying thus giving the body more time to digest and absorb the carbohydrates. The composition of a meal affects the overall g.i. of the meal eaten.
What is Glycemic Load and How Does it Relate to G.I.?
How high blood sugar rises depends both on quantity and quality of the food product. Although the glycemic load has been useful scientifically, using the G.I. is more practical.
Choosing at least one food at a meal with a low G.I. and then mixing it with good fats and proteins will keep your G.I. and your glycemic load low.
For a diet with a lower glycemic load eat:
· More whole grains and high fiber foods that are unprocessed like whole grains, nuts, legumes, fresh fruits and non-starchy vegetables
· Fewer foods with a high glycemic index
· Fewer sugary foods such as potatoes, white bread, white rice, noodles, candy, cookies, pies, desserts
· If you eat a high glycemic food combine it with high fiber, healthy fats and high protein
Why Eat Low Glycemic?
Aside from controlling blood sugar spikes, diabetes and appetite, low-glycemic diets have also been linked to reduced risks for cancer, heart disease, and other conditions.