The glycemic index

Dr. David Jenkins, from the University of Toronto in Canada, developed the glycemic index to measure the speed at which foods break down in the body to produce glucose. While originally intended to help diabetic patients control their glucose levels, it was soon used to help individuals trying to lose weight to control their eating habits and hunger. The key was to decrease the fast breakdown of foods into glucose. Glucose is the natural source of energy for the body. It produces a rush of energy when the food is broken down, and then when it is burned up, it leaves a feeling of hunger and fatigue.

Depending on how fast they elevate the blood sugar level after eating, foods are considered high, medium and low GI foods. Low GI foods rank less than 55 on the glycemic index scale, medium GI foods go from 55 to 70 and high GI foods rank higher than 70. High GI foods break down very quickly in the body and make you feel hungry again soon after consuming them. Low GI foods are slowly digested and absorbed so you feel fuller for a longer period of time after you eat.

High GI foods include:

• white flour products like white bread, croissants, doughnuts;
• heavily processed foods like corn chips, potato chips or pretzels;
• foods high in sugar like cookies, rice krispies, ice cream;
• high starch vegetables such as potatoes and parsnips;
• fruits high in sugar - watermelons, dates and other dried fruits.

Medium GI foods include:

• most types of pasta;
• rice;
• some fruits like mangos, apricots and raisins;
• some vegetables like baked beans.

Low GI foods include:

• most fruits and vegetables;
• legumes;
• cereals that are high in fibers but low on sugar;
• dairy products like low fat plain yogurt, whole, low fat or skimmed milk;
• whole grain breads.

The Low GI Diet

The low GI diet focuses on changing eating habits so that the majority of the foods consumed are from the low GI food group. These foods take longer to break down into glucose in the body. This does two basic things:

• Produces a more even level of glucose throughout the day to avoid those high glucose times followed by the low glucose slumps.
• Stops cravings and hunger from occurring as much.

When these two components combine, they allow the dieter to eat a balanced meal and not experience the "energy slumps". The whole grains and unprocessed foods take more time for the body to convert to glucose and keep the feeling of being full for longer. It also prevents those cravings which tend to cause overeating or consuming foods that are not on the eating plan.

However, the diet should not rely exclusively on the glycemic index as low GI foods aren't necessarily healthy. Foods should be chosen based on their overall nutritional value. The glycemic index is influenced by a sum of factors like: the nutrient content of the foods, the extent to which they are processed, the cooking method, food combination or ripeness in the case of fruits and vegetables.

Products that are high in fat have a low GI as they don't break down as easily as the ones high in carbs. That doesn't mean you should choose to eat high fat foods in order to stick to the index. As an example, whole milk is ranked lower than the fat free or low fat one.

The glycemic index doesn't rank foods that do not contain carbohydrates, like fresh meat, chicken, fish, eggs and cheese. However, it includes processed foods that include meat and diary products. For a healthy low GI diet you should choose lean or low-fat meats that have been trimmed of visible fat, skinless poultry, fish and low-fat dairy products, even though they aren't ranked.

The nutrient content is also very important. Between dates or watermelon and a bag of crisps the obvious choice is the fruit even though the watermelon is considered high GI because of the sugar content and the crips are considered low GI as they are high in fat and slow down the absorbtion process.

It is also important to remember that the glycemic index ranks invidual foods only, not whole meals. Depending on how the foods are combined, the overall GI value of the meal can change and cannot be measured accurately, but the main idea is that including low GI foods in your meal will result in lower GI value overall.

The low GI diet does not lead to rapid weight loss; rather it results in a steady and constant decrease in body weight. The individuals who use this plan find that they have more energy and therefore are more likely to exercise.

So is the low GI plan a diet or a lifestyle? Most experts agree that it is a diet plan that leads to changes and becomes a lifestyle. Eating low GI foods just makes good sense for weight control and maintenance, energy levels and healthy eating.