As a registered dietitian, I am constantly asked about the latest diet craze - Atkins, South Beach, the Hollywood Cookie Diet, the Grapefruit Diet, the Master Cleanse. I've been asked about all of them! It is my job to not only to be educated about these diets, but also to do my homework and research the scientific validity behind them. Unfortunately the average dieter may not be concerned about scientific validity, and who can blame them? They want a diet that is going to help them lose weight quickly, and these diets promise to do just that. But behind the enticing statistics and the convincing consumer testimonials, fad diets continue to disappoint. But how can you tell the difference between a fad diet and a healthful approach to losing weight? There are a few key things to look for that will help you spot what really works and what looks too good to be true. If you ever spot the following three items, back away from the diet.

1. It Omits Entire Nutrient or Food Groups

The Grapefruit Diet, for example, promises quick weight loss by combining grapefruit or grapefruit juice with high amounts of protein at every meal. Salad dressing can be used in unlimited amounts and proteins can be deep fried if you wish, but grains are strictly prohibited. The Grapefruit Diet even restricts dieters from certain vegetables that are higher in starch. Virtually all health experts have come to the conclusion that a healthy diet consists of a variety of foods from all food groups, so any diet that eliminate food groups are not a good idea.

2. It Contains Words Like "Detox" or "Cleanse" in the Title

Although these diets vary slightly in their function and composition, they all claim to focus on foods, or oftentimes an expensive supplement, that contain detoxifying agents that will somehow lead to weight loss. Proponents of these diets insist that our bodies are constantly exposed to toxins such as alcohol, artificial sweeteners, pesticides and smog-- and the only way to cleanse ourselves from these toxins is to follow a detox or cleanse regimen. However, our bodies already have natural detoxifying systems in place such as the liver, kidneys and gastrointestinal system that are designed to eliminate these toxins naturally. So although it may sound tempting to follow a diet that will "cleanse" you, in the end you're paying for something that your body does for free!

3. It makes Some Kind of Sweeping, Unbelievable Claim

"Lose up to 5 pounds in 24 hours!" "Lose weight while you sleep!" - claims like these sound too good to be true...and they are! They rely on shock value to draw consumers in, but lack the sound science to back them up.

So are fad diets ever a good idea? Short answer - no. Knowing how to identify these fads will have you on the right path to choosing a healthy diet that's right for you.