Best way to stop eating unhealthy food?

Do not do the Atkins diet! This is dangerous, as not eating carbs will cause your blood to become acidic (ketoacidosis). Start buying healthy foods that you like, so you can wean yourself off of the bad junk. Don't do the punishment thing, as you are depriving your body of needed calories. Starving yourself will only lower your metabolism, so when you do eat you'll retain all the food as fat, and you'll gain weight.