0.7.1 looked to replace the variable for the 'Crash Diet System' with the variable for the 'Loan System'. In 0.7.4, the Crash Diet System variable was officially removed from the game making all saves before the change no longer work. The saves are just text files which can be edited in a txt document program like Notepad++ for editing, but you would load the save by opening the game, choose 'Load Game' and selecting the save file you would like to load. If your game save doesn't work, you might have to restart, unfortunately...