Yeah it's a hunger suppressant but it can wear out your adrenals if you use it that way regularly and very often. (spikes cortisol if you drink it on an empty stomach; I think it's either the chlorogenic acid).

Coffee is best with a meal; it raises the stomach acid, which improves digestion of the meal. Plus you don't get the cortisol spike when it's taken with a substantial meal.

Definitely wean yourself away from adding sugar to coffee. I have it without any sugar, but a bit of cream, and nible a pastry along side drinking the coffee. So if you can nibble on something sweet, absolutely skip the added sugar in the coffee.