The reason to be concerned about the Insulin Index is that insulin is essentially a storage hormone, evolved to put aside excess carbohydrate calories and store them in the form of fat in case of future famine. In other words, when we eat too much carbohydrate, we’re sending a hormonal message, via insulin, to the body (actually, to the adipose cells). The message is “STORE FAT” It is even worse than that. Not only do increased insulin levels tell the body to store fat; they also tell it to NOT release any stored fat. This makes it impossible for you to use your own stored body fat for energy. So the excess carbohydrates in your diet not only make you fat, they make sure you stay fat.