I used to have this problem. I prepared healthy meals for the day and ate every 2 hours. Always pair a protein with a carb. (Turkey sandwich w an apple, oatmeal w a protein shake, grilled chicken w steamed broccoli and brown rice etc). Exercising for sure helps, it makes you hungry. Try to eat small meals throughout the day. I wouldn't just eat only when you're hungry. It will be hard at first but your body will adjust. It worked for me, I hope this helps. Good luck
Do you do any exercise? A big proportion of being healthy is exercise as well as dieting. Both work well together, if you exercise you are more likely to stick to a healthy diet and then you will reep the rewards. Feeling unhealthy is mot a nice feeling but unhealthy diets and bad ratings habits can make you very fatigued, depressed, bloated, unmotivated and just a general lack in esteem. Hope this is the start of the road to healthier active living for you :)