Sugars stimulate appetite, they will indeed make you hungry, this is one of the reasons why sugar is added to almost everything, and of course the fact that most people simply crave sweet things. Fat has the opposite effect, and induces a large satiety responce.
Sugars digest very quick, 0.5 hours for simple ones, and 2-3 for complex ones. Thus unless you eat very frequently, you can't maintain stable energy levels on carbs alone.
Fats and protein digest *much* slower, 3-5 for most protein, seven for casein, and fats are 5-7 and delay gastric emptying as well, thus slowing down the digesting of whatever else is eaten.
The only reason you would want high sugar intake would be if you were in a very demanding situation and had exausted your glycogen reserves and need to refill them quickly (like an hour) so you would be ready to be active again.
-Cliff