The answer to this question tends to greatly depend on whether you overeat / eat in an otherwise unhealthy way such that it's causing you harm or if you merely don't like the idea of eating junk, so you want to cut back.

For instance, I'm just finishing a medically supervised protein-sparing modified fast where I lost 70 pounds in 5 months by eating only prescription liquid foods and only about 800 calories a day. This has the effect of "rebooting" your cravings. I can't tell you how much I'm looking forward to some fresh vegetables and fruit right now, and I used to be a big junk food craver. Having said that, you'd think 5 months of not eating anything except protein pudding would be difficult, but it was incredibly easy, and I enjoyed it a lot. And it mostly unscrambled the signals to my brain that said, "Eat all the cookies you can find," that ran 24 hours a day.

If that sounds like you, and your weight or other stats like triglycerides / cholesterol / liver enzymes / blood sugar are unhealthy, you should see a doctor and ask about medical weight management right away. I can tell you from experience that it's a lot easier to lose 20 pounds than it is to lose 70, so you can't win by waiting. Also, a great book on the subject is David Kessler's "The End of Overeating." He goes into great detail on the psychological and chemical triggers that induce hypereating.

Now, on the other hand, if you're just prone to snacking on junk in fairly moderate ways, you ought to exercise a little environmental control:

- Shop at farmer's markets for veggies and corner grocers for milk and staples.

- Don't go to the supermarket. If you do go to the supermarket, only shop the aisles with wholesome foods, and never buy anything on the eye-level shelves (the worst, most processed stuff).

- Don't bring junk home. If you buy something junky, buy only one serving. If it only comes in multi-serving packs, take one serving out, then freeze the rest. Make it harder to dig into.

It's also useful to keep records of your eating. If you have an iPhone, I had a lot of success with the app LoseIt. Studies show that people keep off 50% more weight when they keep records than when they don't. If you're mindful of what you're eating and how you're eating it, you create brief openings in which you actually have a choice to eat or not rather than to just eat mindlessly. It also helps to know what macronutrients (fat, sugar, protein, fiber, salt) you're consuming and in what balance. If it's out of balance, shop in a way that balances it out.

Consider foods that induce satiety. Protein has the highest satiety value - if you have to snack, try a protein pudding or shake first, let it settle in your stomach, and see if you're still hungry. Add water on top of that, because thirst often feels like hunger.

Finally, if you seem to be resolving your hunger, but you still feel an overwhelming urge to eat in spite of not being physically hungry, see a doctor or psychiatrist who specializes in eating behaviors. Most people who compulsively eat have no idea they're doing it because A) it snuck up on them over a number of years and B) everyone around them does it too (consider how many startups we've seen full of thin young folks who turned into chunky folks while they worked together).

Good luck!