To build any tissue, fat or muscle, you have to have an excess of calories.

It would be physically impossible for your body to have lost 40lbs of fat and gain 15 lbs of muscle at the same time on only 1300 cal. a day.

The laws of science, mathematics and human physiology would make this impossible.

Was someone else taking your body fat percentage? Because if they were, they were manipulating the numbers. Big time. More likely you lost 20-23lbs fat, 2-5 lbs muscle.

The hcg diet has nothing to do with "re-programming your body's chemistry"and everything with making money by injecting you with a pregnancy hormone and having you consume insanely low amounts of food (I don't eat that few of calories and I'm a woman.)

Luckily you were saved from the normal "hcg rebound" because of heavy lifting. But it didn't retrain your body's chemistry, you ate fewer calories than your body burned.

(I'm not attacking anything you said personally, but my biggest pet peeve is misinformation when it comes to diet and exercise.)