The Glycemic Index is a well documented resource for understanding how food will effect our bodies.
The Glycemic Index is often associated with the nutrition needs of diabetics; the goal is understanding how the food we consume effects our blood sugar. We all should consider looking to the diet of a diabetic for overall health and wellness.
A main component of a Diabetic's Diet is balanced blood sugar throughout the day; that happens to be a plan that will work for most everyone.
A steady state of blood glucose (sugar) keeps the body in balance and prevents the body from storing extra calories. Fat can only be stored when insulin is present. Insulin is produced in reaction to high blood glucose (sugar). That is why you don't want to consume carbohydrates or sugars in the evening. They are fuel that won't be used and the high insulin reaction to those carbs will ensure weight gain; that would be a great plan for a sumo wrestler, are you a sumo wrestler? Then don't eat like one.