Body type is determined by genetics, including things like muscle mass, muscle attachment or bone structure. It can be changed artificially
somewhat with lots of effort and an unnatural diet, with often detrimental side effects, and still, a stocky guy with a body ideal for wrestling or weight lifting will never turn into a lean rock climber or long distance runner.
Allen wrote
1. What is a good name for this concept?
Hogwash.
You will never become a fitness guru.