I think it's a hard problem, especially if you have to tell someone they have control over the cause. (certainly not always the case)

Recently a couple of friends had heart issues. One event went so far as the Mayo clinic and the doctors there said that she needed to stop eating white sugar (one issue at least) because it was scratching her arteries and causing inflammation.

Is inflammation really the problem she is having? She is overweight and didn't want to change her diet. All she heard was "inflammation is the problem", not "change your diet".