There are literally hundreds of diets out there.  Everyone promoting them says that their particular regimen is the only way to fast weight loss.  The problem is that every diet author can't be right - or can they? 

Some diets target calorie counting.  These are usually a very strict regimen that allows certain foods but denies the dieter any contact with other "bad foods."  This type of diet has its following.  Most of these folks are able to stick to a fixed plan for extended lengths of time, without losing their self-control.  These diets do require a stick-to-it mentality that, frankly, most of us don't have.  Give me a diet that only requires strict control for 2 or 3 days and I am OK, but set me up with a diet that requires 2-3 weeks of total control, and I, like most folks, will give in to temptation and blow the diet.

Other diets require that you eat certain key foods or control a particular food group, like the control of fats and carbohydrates that are the biggest item in South Beach and Atkins diets.  The downside to these plans is that they are strict in control of the key foods and must be followed closely for the best results.  A carbohydrate binge on either of these can put pounds on very quickly as many of us who have done this will attest.  This type of diet does have an advantage in the fact that fats are considered "friendly" items, versus the "evil fats" concept of most of the calorie counter plans.  South Beach has the added advantage that it has 3 phases, making it more adaptable to real human needs and wants.

A third group of diets that seem to be popular are the ones that require that you take certain key supplements along with certain foods.  These, like the others, have people that think that this is the best way to get shed of those excess pounds.  The problem with most of these is that the supplements may be very expensive, or they may only be available from a certain vendor who came up with the special formula or blend of ingredients.

The answer to the question is two-fold in nature.  What type of person are you and what has the greatest effect on your metabolism.  If you can't keep to the diet itself, then it won't do you any good.  On the other hand, if a particular diet doesn't work well with your metabolism, it won't do you much good, either.  That means that there is no one diet that fits all dieters. There is no cure-all.  What you should do is to target diets that match you, as a personality type.  Target what you can do, then find the type of diet that will give you the best results in the shortest amount of time.