It's all been said before, but:
Long term- running 3-4 days a week, lifting 3-4 days a week. Running burns the fat, and when done a regular basis, raises your metabolism even when you aren't running. Lifting increases your muscle mass, so it takes more energy just to move around. It's like needing more gas for your truck than your Honda.
Short term, Atkins type diet. High protine, low carbs. If you really have to shed the weight, almost all protine will put you into a state of ketosis (sp?). Bad for your internal organs (liver and/or kidneys, I forget) but you lose FAT fast, keep muscle. Much faster and better ratio than starvation. Again, a RISKY, SHORT TERM solution.
PS, does caffine affect weight? I'm no rocket sceintist, but I thought if anything it would go the other way, as it is legal "speed".