If the body is supplied with all the carbs it could ever want then it doesn't need to burn fat. After many many years of this (depending on the person) the bodies ability to burn fat starts to suffer (Basically the body gets lazy and stops burning fat as well as it should). Burning fat is required to keep your body weight correct so with that system not working properly the body ends up storing more fat than it's burning.
Result = People get fat
Solution = Eat less carbs and eat more good fats
Also, what most people consider begin "Hungry" is just a sugar craving, hunger is a slight pain in the stomach area and not.. "mmm.... want food"