You Must Change Your Life
Try to understand that whatever has contributed to you gaining weight in the past will contribute to you gaining weight today and again in the future. That is, if you don't change it. You must identify where your weakness are.
For instance, you could be a "stress eater" that munches or gorges on food when life gets difficult Are you a "reward eater", rewarding yourself for having a good day or accomplishing something great? Are you a boredom eater that just eats because there is nothing else to do right then? Perhaps you feel like you always must be chewing something because of nervousness. Are you a "social eater" who goes out to a rib restaurant with your friends and gorges on the main entrée but then forces down a dessert (even though you're not hungry) just because it looks good or your friends are having some?
Your first step to overcoming weight loss is to identify what the problem is. You need to identify what motivates you to eat other than normal hunger. Stress, depression, reward eating, social eating, boredom eating, nervousness, anxiety etc. all contribute in a MAJOR way to weight gain. Identify what the problem is and replace the behavior with something else. For instance, the next time you're stressed and you find yourself heading for the refrigerator say to yourself "This is stress eating, I can't do this!" Then replace the behavior with something like going for a walk or reading a book, etc.