What are some good exercise programs to lose as much body fat possible in a short period of time, but still keeping it healthy. A treadmill and elliptical is available to me 24/7. I am 5'11" and weight 185lbs, and I have lots of body fat.
You need to do enough exercise to burn more calories than you consume in a day. For every 3500 calorie deficit, you'll lose approximately a pound. The more strenuous your exercise is, the more calories you'll burn and the longer your excess post oxygen consumption phase will last. Anywhere from 30 minutes to about an hour and a half is considered healthy, as long as you aren't overworking yourself by doing this routine more than every other day.
Just remember, fat loss has very little to do with exercise, it's simple mathematics of calories in/calories out. If you eat more calories than you burn, they get stored as fat for later. If you consume 5000 calories a day and burn 3000 with lots of exercise, you'll still put on a 2 pounds every 3.5 days.
If you are eating a proper healthy diet, you should be able to healthily lose 2-4 pounds each week. Considering that with exercise, one will doubtfully burn more than 3000 calories in a day, so on a 2000 calorie diet, burning 3000 calories, you'll lose 2 pounds a week.