I wouldn't rely on it for fat loss or suppression of appetite. It can help, but you quickly become acclimated to the level and require more, and more, and more, etc. Long term, it's not viable. And, the fat loss isn't that much, anyway.
Before a workout, a cup or two of joe can give you a boost that can help. Plus, two cups of coffee 3-4 times a week isn't that much or that regular, so you shouldn't get acclimated to the level much.
I often have one or two cups before a workout, while I'm finishing up my email, etc. for the day. Then I head to the gym.
Here's a little article from t-nation. Just this week, too.
The Stimulant Roundtable