hi well you can't lose soo much in 3 months cos ull just develop an eatin disorder or something or get cellulite or stretch marks. Anyways cut down on starchy carbohydrates such as bread cereal rice and pasta and eat more fish and chicken and soem salads salsa is also good for speeding up your motabolism and instead of fizzy drinks drink iced water which is very good since drinking it v.cold takes your body 22 calories to get your body back to normal temperature. But you can't just eat healthy foods you also have to exercise try going on a walk everyday do you have a dog?? wlel if you do that is a start cyceling is very good aswell and tones the thighs. And also why not get a swim suit with verticle stripes they make you look taller and thinner and black is also very slimming. Good luck and have a great cruise!! Have fun!