The bigger you are the more fat you'll expend. I think the ceiling must be something like 3 lbs of fuel a day. When I was a bit overweight I lost 2 lbs of fat a day for half a week then it went to 1.5 lbs and ended closer to 1 lbs a day. This is probably what most can expect. The biggest surprise was learning how much visceral fat I had clustering around my organs. A dream to have that cleaned out.