investigation by mother jones said gun violence costs $ 700 per american each year , with a total of $ 229 billion .
the cost of the obesity epidemic is $ 224 billion .
$ 8.6 billion is direct costs , such as prison for those who commit homicide .
indirect costs account for $ 169 billion for ` impact on victims ' quality of life '
over 750,000 americans have been injured by guns in the last 10 years .