Munchkin
Full of Fairy Dust
This is the DS...not the SADI, right?
I hope you won't be surprised or disappointed - it's the science of weight loss.
Most of what you are losing is water - early weight loss is from loss of glycogen stored in your muscles and liver; every pound of glycogen requires 4 lbs of water to keep it in solution. Note that a pound of glycogen has only about 1550 calories, whereas a pound of fat has 3500 calories. When you lose those first 10 lbs (2 lbs glycogen plus 8 lbs of water), you have only lost about 3100 calories total (if you had lost 10 lbs of fat, it would be 35,000 calories).
As big as you are, you probably have 20 lbs of glycogen + water) stored. So your first 20 lbs of weight loss probably only amounts to a 6200 calorie deficit, rather than 75,000 calorie deficit.
The next 40 lbs is NOT going to happen nearly as easily, because your body will resist losing fat FAR more strenuously than losing glycogen, and will slow down your metabolism and increase the efficiency in response to the caloric deficit, further damaging your metabolism. And the minute you stop starvation dieting, you are going to put the weight back on.
I hope you won't be surprised or disappointed - it's the science of weight loss.