I'm gonna get flamed for this, but I am a fatty, and I started off 100 pounds heavier. At 5'8'' and over 290, I had to lose weight and FAST. I got down to about 250 and then I went on a PSMF like Lyle McDonald outlines for 4+ months and dropped down to about 190 on just 600-800 cals/day. I lost some strength....but not a lot to be honest. I think brief, intense workouts that don't burn a lot of calories but still keep strength up and adequate protein is the key. Beyond that, I think people have too much fear about this unless they're talking about getting below 10-12% bodyfat. If you're above this range, your body has fat and will burn it just fine. Once you're around or below 10%, the game obviously changes.