>> Likewise it is physically impossible to maintain organic mass if you consume at a calorie deficit.

Well, this is not an absolute thing. If you reduce your calories your body can sense that, and will reduce your metabolism as well (e.g. reduce your average body temp or other body function). With the reduced metabolism you will probably still keep your original mass. And then we didn't even talk about carb-protein difference, while those still has the same calorie content, their metabolic effect is totally different.

Search for "set point weight theory" for more info.