you can use the eliptical all you want man, they are great and your knees will love you for it. the only way to loose body fat lies in a calorie deficit. make sure you count your calories and your burning more than you eat. also, every five days or so eat more food (refeed). that way you dont go into starvation mode. focus on your diet to loose weight. it doesnt matter what kind of cardio you do - do whatever burns the most calroes.