It is generally accepted that going on a diet of low glycemic foods is a great way to lose weight, prevent certain illnesses and generally encourages a healthier lifestyle. But let’s look more closely at the glycemic index, at both its known benefits and some of the limitations.
Lets first cover some of the main know benefits of using the GI index
- The index was first developed by david Jenkins at the University of Toronoto in their research to find out which foods were best for people with diabetes and in this respect it has been very beneficial for diabetes suffers in identifying foods that they can eat and those foods that they should avoid.
- It helps both diabetes suffers and non diabetes suffers to quickly identify low and high glycemic foods. Therefore, a person that requires quick energy for recovery, for example after an endurance exercise, or a person experiencing hypglycemia, will know from looking at foods that are high on the glycemic index, that these are more suitable than low glycemic index foods.
- Recent animal research provides compelling evidence that high GI carbohydrates is associated with increased risk of obesity and so the glycemic index is a helpful tool in the fight to eradicate obesity.
- Several recent studies have shown that people who follow a low GI diet over many years were at a significantly lower risk of developing both type 2 diabetes and coronary heart disease than others.
- The Glycemic index identifies low GI foods that are associated with slow releasing carbohyrdates and blood glucose levels. The benefit of following the index has been shown to result is less binge eating as energy and appetite satisfaction levels remain relatively constant.
Now lets have a look at some of the limitations of the glycemic index
- foods that are generally considered to be unhealthy can have a low value on the index, for example chocolate cake (GI 38), ice cream (37), or pure fructose (19) whereas foods like potatoes and rice have GI values of 100, yet some countries that have these foods as there stable diet, have low rates of diabetes.
- The glycemic index can only be applied to foods with a reasonable amount of carbohydrate content as the test relies on subjects consuming enough of the test food to yield about 50 grams of carbohydrate in that test food. Fruits and vegetables contain very little carbohydrate per serving and the average person is unlikely to consume 50 grams of carbohydrate from these foods. The results therefore tend to overstate the glycemic level and response of certain foods such as watermelon since it requires the consumpton of a large amount of watermelon to yield the required 50 grams of carbohydrate.
- There are known regions such as Peru and Asia where people eat high GI foods such as rice and potatoes but without high levels of diabetes or obesity. It is believed that the mixing of high and low GI carbohydrates produces moderate GI values. In South America there is a high consumption of legumes, and fresh fruit and vegetables in Asia.
- The glycemic index does not take into consideration other factors other than the glycemic response for example the insulin response of eating certain foods which is measured separately by the insulin index which may be more appropriate for measuring the response of some food contents other than by reference to carbohydrates.
- The values on the glycemic index is influenced by the type of food, its ripeness, the amount of processing involved, the length of storage, cooking methods and its variety e.g a potato will vary considerably depending on its type and can measure anywhere from low to high GI even with the same variety.
- The glycemic response can vary from person to person, and even in the same person within the same day depending on their blood glucose levels, insulin resistance, what they ate earlier in the day as the glycemic response has been shown to be strongly influenced by what was consumed in the previous meal, particularly when meals were consumed within an interval of a few hours.
In conclusion, therefore the glycemic index is not in my opinion to be treated as an accurate measurement that is intended to be rigidly followed. The main attraction of the GI index is its flexibility and the fact that unlike many diet systems on the market there are no strict rules on what you must or must not eat. Instead the glycemic index provides a helpful framework or guidance on what is considered good eating habits for a healthy lifestyle. By remaining within the recommendations of GI eating, a person is able to eat healthily and still comfortably achieve weight management targets, without the imposition of strict and highly inconvenient rules.