There is a big difference between smoking and eating junk food that people are forgetting -
cutting back on junk food is practical, unlike cigarettes where "cutting back" just does not work.
When trying to quit smoking, one has to give it up completely.
When trying to get in shape, you can still have some junk food, just have the discipline to cut back.
But also, try to limit the junk food on hand. Do not be like me and have three or four different kinds of ice cream in the freezer.
Well shoot, I quit smoking, what the hell more does my stupid body want?
Anyways so yeah, moderation.