What it means today is a myriad of food arrangements. Most popular these days is called Low Carb (carbohydrates) diets, Atkins and South Beach to name a few.

A version of this was popular back in the 50's. Prior to the 50's, people didn't "diet" very often. Lifestyles and family meals were more effective along with less pre-packaged foods, level of exercise in everyday activities was higher and eating at fast food places was a rarity.

By the 70's dieting became more organized with support groups forming. This gave accountability and behavior changes more prominence. As society became more aware of health issues and weight, the focus changed to low fat. These changes were positive, with the exception that portions went out of control. A serving of pasta went from one cup to 5 cups. Snacks went from an hors d'oeuvre or two to "fat free" pretzels by the handfuls. Muffins and Danishes went to 5" bagels...Get the idea. The idea was planted if it was "fat free" it didn't count. Sort of like eating nachos with cheese, sour cream, etc. and drinking a diet soda....

The food industry contributed to the problems with "new and improved" products. These new and improved products typically meant they just added more sugars and high fructose. We developed whole new lines of "fat free" cookies, candies and snacks. Only one problem, they still have calories. Often we rationalize if it's fat free we can eat more!

After years and years of studies and research, so-called "advances" in the food industry we can still follow the simple plan before fad diets existed.

Eat whole foods, or foods with minimal amounts of processing.
Avoid "white" foods. Try sweet potatoes rather than white. Look for whole grains for breads and pasta rather than white.
Consider other sources for breads all together
Rather than simply drinking the juice, eat the whole fruit which has a lower glycemic index and more fiber.
Eat the majority of your carbohydrates in the form of fruits and vegetables rather than breads and cereals.

It's not that carbohydrates are so bad. They are quite necessary. The real culprit in weight management is simple carbohydrates.

Not all carbohydrates like pasta and potatoes are to blame. However, overly refined foods such as white bread, snack foods, sodas, juices can become a source of weight gain. The best choices are the whole grains or ones that have minimal processing.

Take a great full spectrum vitamin/mineral supplement.
Get active. Anyway you look at it, you got to exercise!
Get motivated to change your eating habits.