I take zantrex and for you only being 16 I would have to say no...
I think you should try something else, they may be hard on you being young.Try to do it natural.
Cut out fast food, soft drinks,fried food,sugar, and add walking,swimming,work out tapes,ride a bike.
Try and use ****** to help watch what you eat.Its free all you have to do is add what you eat and your workouts and it gives you your total caloire count for the day...You can set a goal and it will tell you how many days you have and how much weight you need to lose each week to get to that goal weight.
Maybe you have tried these and it didnt work, I just think the caffeine may be to much for you.
Good luck and no matter what happens enjoy yourself on vaction.