In the case of disabled people they should be able to buy whatever they want as long as they maintain height/weight standards. Poor people though should have multiple restrictions and, honestly one of the best programs I have ever seen as far as health oriented is WIC (Women, Infants and, Children) when my wife was approved for it she was able to buy beans, milk, cheese, rice and, a few other things as well as being given an allotment for fresh produce. I think food stamps should be modeled after that.