Research on food, mood, substance abuse and cravings is still fairly new and poorly understood. Drugs and alcohol can override normal hunger and appetite cues, so now you are learning new habits. Blood sugar fluctuations from irregular meals may cause cravings and mood swings, which were formerly cues for using drugs or alcohol. Cravings are associated with desire, not necessarily with hunger or a need for a specific food.
Don't skip meals. You are going to have sugar craving when you are hungry. If you go long periods without eating and your blood sugar gets low, you are going to over-indulge in sweets and carbohydrates. After eating a meal high in carbohydrate or sweets, insulin levels stay up a long time and cause your blood sugar to crash later.
It is important to eat healthy snacks like fresh fruit, vegetables, low fat cheese or nuts to keep yourself satisfied. Incorporate exercise into your daily routine. This will help increase your metabolic rate, and will keep you feeling good about yourself. So be sure to start your day with a healthy substantial breakfast, and supplement this with healthy snacks to keep your cravings in check.