It seems like every couple months, there's a newer, more effective diet that's the rage of Hollywood. The diet gets really popular because of the star power and press it receives, hangs around for a few years, then flickers until no one even thinks twice about doing the diet again. These are known as Fad Diets.
Just like anything else (Pogs, Furbies, Pet Rocks, etc.), most diets that use some product or service fall into the fad category. Most of these Fad Diets are loosely based on science, if they're even science based at all. The problem is that most of the time, these diets are such a drastic change in your normal dietary patterns that they will make a difference, but it is commonly short lived.
For example, one of the biggest diets on the scene right now is the HCG Diet. The HCG diet is loosely based on the premise that getting a regular supplement, or even injection, of HCG, aka Human Chorionic Gonadotropin (a normal physiological hormome most prominent in pregnant women, it's actually the hormone that's tested when a pregnancy test is performed), will help someone in their quest for weight loss. However, when you actually start looking into the diet portion of the HCG Diet, the daily caloric intake (how many calories you eat) is severely restricted. And if anyone severely restricts the amount of food they eat, they're at least going to lose some weight. Not to mention that severely restricting how much you eat is unhealthy. Your body needs food.
On the unhealthy note, some fad diets are just plain dangerous. Remember the Atkins Diet. Basically you wouldn't eat any carbs and then load up on proteins. It didn't matter if the protein was bacon or quinoa. But of course more poeple are going to eat bacon and other "unhealthy" meats instead of quinoa. These unhealthy proteins can lead to severe problems like atherosclerosis (plaque in the blood vessels) and other diseases. In fact, Mr Atkins himself died from complications typically linked to a diet rich in high fat foods.
So the next time that you hear that Scarlett Johansson used the X Diet to lose 15 pounds for her next role or Ryan Reynolds tried the Y Diet to beef up for his next gig, just pass it off as another one of those tricky Fad Diets. After all, you know what you should and shouldn't be eating. Just listen to that little voice in your head and reach for a handful of sugar snap peas instead of a handful of Cheetos.