Equicalorie is not Equimetabolic.
If you ingest 100 calories from protein or fat sources ( like lean meat or oils ) versus 100 calories from carbohydrates ( bread, pasta, sugar etc) it activates different hormonal cascades in your body.
This is proven by people losing weight with Atkins diet even when they ingest enormous amount of calories from protein and fat .
In contrast, if you ingest carbohydrates then you have to watch the calories closely.
We are now discovering that this sensitivity to different food groups may lie in your genes.
Hold your breath..
That day might not be far when we can take a genetic test and prescribe a life style based upon your genetic make up.