There is a lot of debate in regard to which diet is better and everyone has a horse in this race. Low carb, high carb, low fat, high fat, low protein, high protein, Zone, Atkins, Paleo... did I miss one? They all make an effort to substantiate why they are superior to other diets and why you should use it. But do they address the real problem or even mention what the problem is? Nope... and there's a reason for it. The problem isn't the diet or the number of calories you consume - it's the quality of the food you eat.
It doesn't matter what diet or eating plan you follow if you are still consuming processed foods that the body is going to convert and store as fat. The one thing that researchers and scientists agree on is that if you really want to lose weight permanently then you have to change how and what you eat. Primarily you need to realize that the number of calories you consume is secondary to the quality of the calories you consume. In other words, if you are eating bread, pasta, and processed carbohydrates then you are going to continue to store fat and not burn it.
NOTE: this brings into question the meal replacement diets in my mind as well. The calories that you consume on these diets, in the form of highly processed meals, that while they may offer short-term weight loss but not lasting results. In addition, because of the high level of processing that the food is subjected to, are the calories actually usable by the body or are you in effect starving yourself?
Check out this article from the NY TImes that discusses this problem as well as links to other articles that contains research from Lancet and JAMA. It may make you think twice about your next meal...