It seems almost as if there is a new fad diet every week. Many of these contain elements of truth, but on the whole they contain much more good marketing than good science.

There is the 3-day diet, which touts eating little more than fruits for three days, followed by vegetables or meat or grains the other days. There are lots of variations.

While it's certainly true that eating fruit regularly is a key element to good health - most contain needed carbohydrates, vitamins and fiber - eating almost exclusively fruit for three days leads to imbalance - in carbohydrates, fiber and additional otherwise healthy components. To an extent the body will equalize and store what it needs for later, but there are limits.

Similarly, the 'low carb, high protein' diets, such as Atkins, recommend cutting way down on carbohydrates and eating substantial amounts of food high in protein. Here again protein is vital to proper nutrition, but so are carbohydrates. Putting too much emphasis on the first over the second leads to rapid, temporary weight loss, but at a high cost.

Carbohydrates are essential for supplying energy for all biochemical processes. Though the body, when needed, will use other sources, such as fat and protein. Too great an emphasis on protein reduces the ability of the body to store and regulate the appropriate amount of water, whereas carbohydrates help that.

There are very attractive sounding 'chocolate diets'. Nearly everyone loves chocolate and, contrary to some reports of a few years ago, it is healthy - in moderation. Chocolate contains anti-oxidants and other compounds that are helpful. But, as with anything, too much of a good thing is just that - too much. Also, since many will seek chocolate in forms that come with high fat, high sugar amounts it's possible to get some not-so-helpful elements along with the good.

There are ultra-low fat diets. Once again, the problem isn't with reduced fat, but going to extremes. A certain amount of fat in the diet is a healthy thing.

Any diet which makes promises of radical, rapid or quick weight loss - or any other extreme claim - is almost guaranteed to be more harmful than helpful. The human body has evolved over millions of years and decades of good nutritional research still confirms the common sense truth: balance is good, moderation is healthy.

Eat moderate portions at regular intervals of fruits and vegetables (for vitamins, carbohydrates and fiber), grains (for carbohydrates, vitamins, minerals and fiber), protein (for amino acids) and dairy products (for calcium, unless you're lactose intolerant). For the average person, between 2000-2500 calories per day is appropriate. Less for women, on average, and for those seeking rapid weight loss.

A balanced diet, coupled with age-appropriate, moderate and regular exercise, will lead to a healthy percentage of body fat, good muscle tone and a well-tuned system. You'll find you feel better and look good.