old post but I haven't checked this part of the forums in awhile.
To lose weight the fastest you gotta do High Intensity Interval Training (HIIT). Ever done "suicides" in gym class? They're basically those. You sprint as fast as you can for 10-15 seconds then jog for 40 secs - 1 minute. This makes your heart constantly work instead of staying at a steady BPM, and this speeds your metabolism to ridiculous levels. You will also lose a lot less muscle than normal cardio. Look at pictures of sprinters and then pictures of marathon runners and you'll see a huge difference. Weight lift on Mondays, wednesdays and fridays with no cardio, then tuesday and thursdays do HIIT. Weight lifting burns a ton of calories on its own, and the HIIT will help it even more.