Spotting a fad diet is not that hard. All you have to do is ask yourself “Does this sound too good to be true?” If it does, then it probably is. Fad diets often:

Promote unrealistically quick weight loss (this kind of weight loss primarily results from a loss of body water)

Limit food selection and have very specific rules, such as having to eat soup for lunch and dinner or drinking their shakes for breakfast and lunch

Use testimonials from high-profile people or celebrities

Claim their diet and products work for everyone no matter what age, size, or health problems they may have

Are often highly expensive

Carbohydrates have been given a bad rap over the past ten years due to fad diets such as the Atkins diet, the Four-Day Wonder diet, and the Scarsdale diet. These diet plans recommend a low or restricted carbohydrate approach to quick weight loss. The primary reason these diets work in the short term is due to calorie restriction. If you eat less than 20 percent of carbohydrates in a day you are most definitely cutting out calories. Carbs are a quick and easy way to eat something that's fast and inexpensive. Think about most snack foods — crackers, pretzels, chips, popcorn — they're all primarily made up of carbs.

Now take a look at a regular meal. You have a sandwich, a salad, and a soft drink for lunch. The bread from the sandwich is a carb, the salad is all carbs, and the soft drink is also a carb. According to the low-carbohydrate diets, the only thing you are able to eat in that meal is the meat and cheese in your sandwich and a few veggies.

This is merely limiting how much food you intake. This does not seem so bad for one meal, but when you deplete your body of carbohydrates you are depleting your body of energy as well. Without energy it is very hard to exercise, and when you do you are likely to experience a great deal of muscle fatigue and muscle cramping due to lack of proper nutrition.

Low-carb diets can lead to quick weight loss, but since these diets do not include fruits, vegetables, and whole grains, nutrition experts do not recommend them for a healthy diet. The American Heart Association has also warned against following such a diet due to the high amounts of fats and proteins required for such a plan.

Think of carbohydrates as the fuel for your body. If you are exercising regularly, then you are going to need a certain amount of carbohydrates in order to get through your training session. If you have a day of the week in which you do not have activity, then it may be appropriate for you to consume fewer carbohydrates on that particular day. Think of the car analogy. If you are driving a long distance, you may need to fuel up your tank before you hit the road. Of course, if you are only going to be driving a few blocks and back, there's no need to stop at the gas station.

Low-fat diet plans usually limit your daily intake of fats to 5–10 percent of your caloric intake per day. The most common low-fat diets are the Pritikin and the Dr. Dean Ornish diet plans. These are not usually harmful to a healthy adult. The problem is they are very hard to stick with. People become bored with the limited choices of food they have. Remember, some fat is needed for the body to function properly. It is recommended to have a little more fat in your diet than the low-fat diet recommends.