The glycemic index is a scale that measures how quickly carbohydrates are broken down into glucose. The original purpose of the glycemic index was to help diabetics keep their blood glucose under control. The glycemic index has recently attracted a lot of attention in the bodybuilding, fitness and weight loss world and is all the rage these days. Nary an issue of a fitness or bodybuilding mag is published without some reference to the glycemic index and diet books such as "The Zone," and "Sugar busters" worship the index like some kind of idol. According to advocates of the glycemic index system, foods that are high on the scale such as rice cakes, carrots, potatoes, or grape juice are "unfavourable" and should be avoided because they are absorbed so rapidly and are therefore more likely to convert to fat. Instead, we are urged to consume carbohydrates that are low on the glycemic index such as black eye peas, oatmeal, peanuts, apples and beans.
While the glycemic index does have some useful applications, the flaw in stringently adhering to the glycemic index to dictate all your carb choices is that the index is based on carbohydrates being eaten by themselves in a fasted state. An effective fat-burning, muscle building diet is based on always combining carbs and protein together. When carbs are eaten in mixed meals that contain protein and some fat, the glycemic index loses some of its significance because the protein and fat slows the absorption of the carbohydrates. For example, mashed potatoes have a glycemic index near that of pure glucose, but combine the potatoes with a chicken breast and vegetables and the glycemic index of the entire meal is much lower than the potatoes by itself. Similarly, rice cakes have a very high glycemic index, but if you were to put a couple tablespoons of peanut butter on them, the fat would slow the absorption of the carbs, thereby lowering the glycemic index of the combination.
A far more important and relevant criteria for selecting carbs is whether they are natural or processed. To say that one should not eat natural foods like potatoes simply because they are high on the glycemic index is ridiculous. Potatoes are an outstanding source of starchy complex carbs. Eaten exactly as it is found in nature, an 8 oz potato has only 170 calories, almost no fat, is loaded with essential nutrients and is satisfying to eat. Compare that to 8 oz of a processed carb such as pasta, which has 840 calories. Which do you think is the better choice if you want to get ripped?