Hollywood health fads come and go–and some seem to hang around and never quite disappear altogether. One of those with staying power is the juice cleanse.

A juice cleanse is a method of detoxifying your body by drinking only fruit and vegetable juice. It can be expensive. It is said to help starlets fit into those unrealistic dresses on the red carpet. And it is once again establishing itself as the "hot" Hollywood health trend, which may tempt you into trying it.

Before you go out and buy a juicer and load up on melons and exotic lettuce, consider the following:

Juice CleanseJuicing is expensive. There are a lot of companies selling bottled "juice cleanses" right now. And they are expensive. The BluePrint Cleanse, for example, which is sold in a plastic bottle and claims to use a process that gives you maximum nutritional value in every serving, costs between $65 and $80 per day–and that is on the inexpensive side.

It may not work. Juicing advocates spend a lot of time espousing the benefits of consuming nothing but juice, but the there is little scientific evidence it actually does your body any good. Consider the Life Juice Cleanse, which costs between $60 and $180 per day. It's full of Himalayan sea salt, which is said to help your body digest all the helpful vitamins and nutrients in the bottle. However, experts say that paying a lot for a little Himalayan sea salt probably doesn't help your body absorb the nutrients from the fruit and vegetables.

Your body can only take so many vitamins and minerals at one time. Even ultra-fancy juicing techniques, such as those used in Liquiteria, that claim to leave the maximum amounts of vitamins and minerals in a bottle of juice might not be worth it. This is because your body can only take so much of a good thing. Ever notice that your urine is a bright-yellow color after you take a vitamin? That's the excess nutrients leaving your body.

The bottom line is this: Drinking fruit and vegetable juices is good–just do it in moderation.