Yes I did a bit of a look into that too and being overweight affects a fair bit,high blood pressure,poor fitness,all the factors of being over weight are to be vectored in I would say.
I guess thats why the NAUI and PADI dive tables are so conservative because they are broad spectrum to allow for the different pysical conditions of divers.
My GEKKO even has a mode to make the standard tables more conservative allowing for fatigue etc etc...
The pysical condition of your average Navy diver would be completely different to that of your average Recreational Diver....hence we dont use the "straight" Navy tables...(stating the obvious arent I..
If I remember correctly the Navy tables were a lot less conservative than any others I have seen.