Occasionally we get desires to do things that we intellectually don't want to do. When it comes to food, these desires show up as cravings. Often these cravings are for foods that aren't usually the healthiest. Most of us have been taught that discipline is a great way to "combat" these cravings.
The challenge with discipline is that it is a technique to rid desire, but discipline based on desire. When someone says, "I have discipline," what they often mean is that they are experienced at taking one desire and making it stronger than another. Not that this doesn't get the job done. In fact, discipline often does works, temporarily. However, discipline will ultimately always let us down because one day (for some people, many days) we'll have a desire that can't be trumped.
So what are our other options? If discipline can only get us so far, what else do we have?
When a strong craving or desire shows up, just watch it. Let it be and pay attention to what it is saying. Notice it and how it is promising you that, "If only I had this, my life would be better."
When you watch your desires, you will begin to see their root conditioning (e.g. I'm feeling like I need this food because it is emotionally familiar). After the conditioning is observed what will start to show up is a natural detachment to your story, the story of why you need what you think you need. Slowly you will begin to NOT identify yourself with the thing that you once "were". Ultimately, a greater degree of peace will start to arise.