FROM SOUTH BEACH TO SONOMA, Americans are struggling to lose weight and keep it off. We jump from diet to diet in search of a quick-fix solution with lifelong results. What we don't realize is that the only true "Diet Revolution" is no diet at all.

A fad diet typically promises fast, dramatic weight loss through a restrictive plan. These get-thin-quick plans have been around for centuries despite unimpressive long-term results. William the Conqueror is said to have been one of the first fad dieters, concocting a regimen of booze and bed rest. He lost some weight, only to lose his life in a horseback riding accident.

While his tale is comical, the dangers of fad dieting are no laughing matter. Yo-yo dieting, which results in a cycle of repeated weight losses and gains, has been linked to a number of health problems including a weakened immune system. Extreme dieting can lead to malnutrition, irregular heart rhythms, and injuries due to electrolyte imbalance.

Yet the best reason to avoid fad diets is that they just don't work. Even low-calorie plans become ineffective over time because as the body adjusts to fewer calories, it burns less fat. Unless dieters also increase their physical activity to adjust to a lower metabolism, their attempts to lose weight will fail. At the same time, dieters often become preoccupied with food, weary of restricted meals, and frustrated by their declining results. All this can lead to overeating, even binge eating.

This is why nutritionists promote a no-diet approach to weight loss. They suggest the best way to lose weight and keep it off is to set realistic weight-loss goals, watch portion sizes, get regular exercise and eat well-balanced, healthy meals.