Not only is it possible to lose weight for life, it is actually a lot easier than most people think.
The diet industry like to make a huge deal of losing weight, making enormous amounts of money off of common folks like you and I when in fact, the knowledge to take off weight is freely available on your good friend the internet.
The key, and there is only one true key, is behavioral change.
Re-patterning your life, restructuring your mental processes.
Instead of, for example, picking up fast food for lunch every day, make one small change, of bringing a bagged lunch from home. Now it'll seem awkward the first couple of days, but consider the advantages:
By preparing the food yourself, you control what's in it. You control it from the simplest sandwich to the most ornate sushi. You can begin to take power regarding food, because that's what you're loosing by buying a fast food meal.
Financially of course, a peanut butter sandwich and an apple is one heck of a lot better for your wallet, than the nine bucks you would spend at Subway for a full meal. It's a case of where less is more, and in this economic downtrend, you need every advantage you can get. Think about this, as well. Once the downtrend has reversed itself, your habits won't go anywhere, and you'll end up saving even more money in the long term.
You have just made a behavioral change. Congratulations.
That is all there is to it.
When you park your car at the grocery, park as far away as you can, and then walk in. Do not use a shopping cart; use either your fabric reusable bags, or one of those plastic hand baskets.
Why?
First, you are less likely to make huge amounts of purchases if you have to carry everything. You will be thinking more and more about what you're buying. You are developing a sense of awareness, and critical thinking, and this is what the commercial diet industry does not want you to have. You're also getting a touch more, very subtle exercise by carrying everything.
Stay of course, to the outside lanes of the grocery store, and in particular, produce is your special friend. Very few fruits and vegetables have large amounts of fat in them, and ones that do generally have 'heart healthy' fats such as avocados. These are fats that are good for you, as opposed to the artificial fats that aren't.
By making small behavioral changes, you'll also start to change your thinking, your relationship with food. That's the name of the game. This is how permanent lifestyle changes are made. This is how you develop healthy habits that you can pass onto your children, so that one day as a culture, as a species we won't need to worry about losing weight for life.