I guess I'll throw my 2 cents into the hat as well.

I lost 40 lbs over the span of a couple of years. I took it off slowly in about 12 lb chuncks (and I'd kind of stagnate for a few months before starting the weight loss again -- I swear that helped it STAY off in the long run). I was on Weight Watchers and learned some good stuff from them. Ultimately, it was just the right combination of diet and exercise that made the difference for me. Here are some of the things I learned ...

Everyone needs SOME fat in their diet. If everything in your cupboard and fridge says "fat free," you're making a mistake. Instead of a fat free salad dressing, try olive oil (just 1-2 teaspoons) & vinegar with some herbs and a dash of Splenda for sweetness.

Carbs were my enemy. I almost completely wiped them out of my diet. I'd have bran flakes for breakfast and a wheat wrap for lunch (with meat, lots of veggies, no condiments). I completely cut out pasta, rice, potatoes and bread. I found it to be true that carbs actually caused me to feel hungry faster.

Lean proteins are my friend. A very small portion of scrambled eggs at 8:30 keeps me satisfied until lunch at 1:00. However, a huge bagel with margarine at 8:30, and I'll be hungry by 10:30-11:00. So, proteins really do stick to your ribs!

Many experts recommend that you graze instead of eating "meals." Combining the lean proteins, less carbs approach, I'd have one scrambled egg for breakfast (and coffee) or some bran flakes. Mid morning maybe a slice or two of turkey. And water. Lunch I'd have my wrap (no condiments, no chips on the side!) and water. Mid-afternoon maybe some tuna with lemon juice or a TOUCH of lite mayo or some nuts. And water. Dinner a HUGE salad, or a piece of fish with a HUGE portion of veggies. Dessert would be some peanuts in the shell (they take longer to eat) and water. And I always take a vitamin and calcium supplement.

Then there's the exercise part of the plan. Whatever you are doing for exercise, either double it, or change it altogether. Sometimes your body needs a kick-start by using different muscles than you usually do. (And weight training is a must.)