Good question @victoriacalloway. It's highly individual. The only reason to completely exclude a certain food group is if the individual has an intolerance to that food. Other than sugar, people can be intolerant to all of the foods you mentioned and many more.

If someone is intolerant, I would advise removing that food. If they are slightly addicted to that food, it depends on the person. Some people can eat a little and not have a problem, every now and then. Some people must avoid completely so as not to trigger their cravings!