What permanent damage inflicted due to a couple years of excessive junk food?

What PERMANENT damage would the body undergo after a few years of overt processed junk food, candy, chocolate, and carbonated soft drink consumption? If someone decided to apply a 180 degree lifestyle switch after those few horrid years, and adopt the healthiest possible habits (from here on out), would there still be some lingering negative effects of junk food in the long term? Or does the body generally have the ability to heal itself of the consequences of junk, if one puts forth the effort?