What I’ve read is that it is easier to gain muscle (weight) after you have lost your original fat. In other words, concentrate on losing the “hard-to-shed” fat that has been stored in your body for years, before focusing on increasing muscle mass (weight-gain). This makes losing weight while gaining muscle mass (strength) easier in both respects. By changing to a routine to focus on a strength and fat-burning routine you will see a difference in your body all around with less effort.
Although I guess it really depends on your workout goals, I am just suggesting that if you are 40lbs. overweight you may be putting more stress on your body and your heart, and not getting an optimized workout for your body. It will take you longer to achieve the exercise goals you are looking for.
I would imagine also that 40lbs overweight, you may actually see a difference in BPEL after some weight is lost, but it really depends on where that fat is stored on your body and for how long its been there.