Obesity significantly increases one's risk for several diseases including diabetes, heart disease, and many cancers, so prudent dieters are seeking methods to slim down. Historically, low fat, high carbohydrate diets have been the most common weight loss strategies, but depending on the quality and quantity of the carbohydrates chosen, this may result in hyperglycemia and increased insulin demand. The glycemic Index, or GI, diet was established to help prevent this.
Glucose Metabolism
Glucose is the primary source of energy in the body and the body works hard to tightly maintain it at a consistent level. When blood glucose, or blood sugar, goes low, you become tired and hungry. After you eat, glucose rises. But if this increase is too rapid, the pancreas will secrete more insulin to bring it back down. This excess glucose is then converted into fat for storage. The theory behind the GI diet is that if someone consumes fewer foods that cause fast spikes in blood glucose, the appetite will be suppressed, fat storage will be slowed and unnecessary weight gain can be avoided.
GI Overview
The glycemic index is a dietary tool developed approximately three decades ago by Dr. David J. Jenkins. It categorizes many foods based on their short-term effects on blood glucose. Foods shown to cause sharp spikes in blood glucose are considered high glycemic index foods, while those that are slower to absorb are given a lower GI rating. Pure glucose has a GI of 100 and is used as the reference point. The lower a food is on the GI index, the less it will affect your blood glucose level. In the book "The G.I. Diet Clinic," a color-coded system is described in which foods are grouped into three color categories based on assigned GI ratings. Green, or low GI foods, are OK to eat anytime; yellow foods have moderate GI levels and are to be eaten less often; and red foods are discouraged because they have high a GI ranking.
Benefits of GI
Many foods that are low on the glycemic index are known to be part of a healthy diet including fruits, vegetables, whole grains, lean meat, low fat dairy and healthy fats. Foods high in refined grains and added sugars are eliminated. In the November 2010 issue of "The New England Journal of Medicine," T.M. Larsen and his research team at the University of Copenhagen in Denmark concluded that diets that modestly increased protein rich foods and modestly reduced carbohydrate foods that caused rapid spikes in glucose, seemed to lead to weight loss.
Word of Caution
As with any diet, proceed with caution as the glycemic index diet is not perfect. For example, watermelon is a high GI food but is also a very good source of vitamin C and A and can be included in a healthy diet. Many low GI foods are also high in fat and calories. Potato chips, for instance, are a low GI food but should still be eaten in moderation due to their saturated fat and sodium content. The glycemic index of a food can be affected by preparation methods and by their combination with other foods. Finally, every person is unique and may have different glycemic responses to a particular foods.
References
- "The Journal of the American Dietetic Association"; Glycemic Index, Glycemic Load, and Prevalance of Metabolic Syndrom in Cooper Center Longitudinal Study; Carrie E. Finley, et al.; December 2010
- "The New England Journal of Medicine"; Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance; T.M. Larsen, et al.; Nov. 25, 2010
- "The GI Diet Clinic"; Rick Gallop; 2008
Member Comments