As far as I know, there are no differences when buying shoes for a weighty runner. You need a stability shoe with decent cushioning to prevent you from injuries by good shock absorption. An average running shoe is created to endure two and half times your weight. More important for you is to make a wet test to see what kind of foot you have – normal, flat or high-arched and after that pick your shoe according to that. You should bear in mind that if your weight is excessive, then you will have to change your shoes more frequently. When you notice that they have lost their shape and that they’re not comfortable as they used to be, buy a new pair.