Maybe, though you can't always believe what these guys claim. They might be completely clueless or simply lying for whatever stupid reason. I'll give a couple of ridiculous examples of pros fucking around. Vic Richard claimed to eat 30,000 calories day, in reality it probably was like 8K on a particularly heavy day, just based on his stats. Nasser claimed to eat 80 grams of protein a day in the off-season, in reality he most likely ate more than that just for breakfast.
There is simply no way that Juan Morel would need say twice the calories compared to someone like Ramy. If you starve for a week you could have a monster cheat day and it all averages out pretty similarly.
Yes, well bodybuilders lie for many reasons, I still believe that there are big differences between the metabolisms of these guys, although with all the drugs they are using it is impossible to know if their metabolism is more fast or slow, or they just are hacking it.
Are you talking about screwed metabolism due to some medical issue or screwed from low calorie diets causing "metabolic damage"? Maybe both? They have looked at these things. In the case of diets, they have looked at metabolic downregulation from long term starvation and also measured things in the recovery period, for example in the Minnesota study I linked to. The downregulation might not be as big as you think.