You hear so much bad press about 'fad' diets and people who have purchased diet advice and not had any results that it is easy to become jaded about the whole idea of losing weight. So do any of the diets you can buy actually work?
Do not forget that really all we need to do to lose weight is to eat a balanced diet which gives us slightly less calories then we need (roughly 2000 for women and 2500 for men), and then exercise gently too. Or cut out the exercise and cut down on the calories per day instead.
The diets that are available just help you to regiment that and give you a plan to follow, along with their own variations on that concept like cutting out carbs. The more extreme diets like the Atkins diet usually do work, but they are not usually sustainable, and as soon as you switch back to your normal habits then you will find the weight coming straight back.
The better diet systems give you an intense introductory phase, usually around 30 days, where the system is more strict and you will see good results, then they switch over to the maintenance phase which forces you to change your habits to make them more healthy and keep that weight off.
This is a much better way as you still get the motivation early on with the intense phase as you see your weight drop, so you stick out the full 30 days, but then after you do not fall back into your old habits, plus if you need to lose more weight you can just repeat the intense phase again until you get to where you need to be.
Systems like Slimfast® and Medifast help you to cut down on your calories by substituting some of your meals for their items like shakes and soups. The companies make sure that while the replacements are low in calories then they contain lots of essential minerals and nutrients that you need, this is far better than just missing out on meals to try and cut down your calorie intake. You can even try the Cookie Diet (TM) which uses special cookies as meal replacements!
So yes, some diets do work, in fact most do but some of them are a bit extreme to be healthy in the long term, of course no diet works if you do not stick to it … There are of course scams out there and dubious promises, but if you research them first you should be able to find the one that is right for you and avoid getting ripped off.