A glycemic index (GI) diet focuses on foods that prevent rapid spikes in blood sugar. Many popular weight loss diets have adopted the principles of the glycemic index, which was originally developed for diabetes patients to help control blood sugar. Low GI diets improve glucose and lipid levels in patients with Type 1 and Type 2 diabetes. Low GI foods also aid in weight loss because they are digested more slowly, helping to control appetite and delay hunger. Insulin levels are also improved in people with insulin resistance.
Insulin Resistance
When you eat, your pancreas secretes insulin to help blood sugar, also called glucose, get into the cells of the body to burn for energy or store. If insulin levels stay high in response to high blood sugar, the cells become resistant to it. The insulin loses the ability to help the glucose get into the cells, so blood sugar levels remain high. Insulin resistance is associated with many health problems, including Type 2 diabetes, polycystic ovary syndrome, obesity, high blood pressure, stroke and heart disease.
Basic Principles
Carbohydrate-containing foods affect blood sugar more than protein or fat since they are made of glucose molecules linked together. When the longer chains break down into glucose or other simple sugars, the intestine absorbs them, releasing them into the blood. In general, more highly processed foods raise blood sugar more quickly than "whole" foods because the body has to do less to break them down. For example, orange juice will raise blood sugar more quickly than eating a whole orange. The fiber in the orange helps it digest more slowly. Cooking methods also affect GI. For example, pasta has a higher GI the longer it is cooked, and mashed potatoes are higher in GI than a whole baked potato.
Glycemic Index Values
Foods are scored on a scale of zero to 100 based on how they compare to a reference food, usually white bread or glucose. A GI of 70 or greater is considered high; these foods are more likely to raise blood sugar levels. Examples include plain white bread, skinless baked potatoes, instant white rice, and soda crackers. Medium GI foods are between 56 and 69. Sweet corn, bananas, raisins and other fruits are in this category. Low GI foods are lower than 55. This category includes skim milk, raw apples, peanuts and many beans.
GI Diet Tips
Many foods remain unranked, and most foods are ranked as a single food item, not as part of a mixed meal. Foods higher in fat digest more slowly and are more satiating. For example, peanuts have a very low GI but are high in calories. Thus, although a low GI food item will not spike blood sugar, remember that any food eaten in excess will lead to weight gain. Consult food labels and watch portion sizes. Eating more whole foods and high-fiber foods, consuming some protein at each meal and snack, and focusing on foods with monounsaturated and polyunsaturated fats should help ensure an overall low to moderate GI diet, help balance your blood sugar and aid in weight loss.
