There are two eternal truths about diets: One, if properly followed they will result in weight loss; and two, most people will cheat.
Only an iron will, an in-house nutritionist or numbed taste buds can guarantee a successful diet. But this isn't just a question of discipline. It's also boredom, timing and preconditioning. For example, an athlete accustomed to consuming large amounts of food will find it hard to reduce his or her caloric intake when no longer in training. Even if the foods are tasty--the Atkins diet actually encourages people to eat bacon and butter--people will hunger for the forbidden.
The reason is that many diets are too restrictive and are not designed to be sustained over time. For example, go to a spa, drink lots of water, go for hikes, do yoga, eat 1,000 calories a day and lose weight. Within a short time of coming home, though, the weight that had been lost, like the prodigal son, has now returned.
Many diet books offer the same kind of planned obsolescence. Spas want people to come back. So do most diet programs and low-calorie foodmakers. The last thing these companies want is for people to get so thin they won't need them anymore.
Diets are, after all, a business--and a staggering successful one. In 2005, according to Tampa, Fla., market research company Marketdata Enterprises, Americans spent more than $48.6 billion trying to diet. That is up 47% from 1989.
The key to losing weight is not through quick fixes and fancy spas, no matter how much we may enjoy them, but rather it's taking a more sensible and long-term approach that balances diet with lifestyle.
"Lifestyle is very important. You have to think about what it encompasses, like exercising and taking the time to actually enjoy meals," says Connie Guttersen, author of the latest in best-selling weight-loss books, The Sonoma Diet.
Guttersen's diet focuses on ten of what she calls "power foods": almonds, bell peppers, blueberries, broccoli, grapes, olive oil, spinach, strawberries, tomatoes and whole grains, while combining the flavorful cuisine of the Sonoma wine country, which she says, is a combination of Asian, Latin American and Mediterranean cuisine. " The Sonoma Diet is about enjoying foods so it's easy to stay motivated and stick with it."
Organic lifestyle and eating has also taken its place among popular diets. Companies such as the Austin, Tex.-based Whole Foods(nasdaq: WFMI - news - people ) are exploding with stores in every city. They guarantee consumers food and other items that are free of pesticides, preservatives, sweeteners and animal cruelty--the basis of an organic lifestyle. In 2005, Whole Foods saw a one-year sales growth of 21.6%, with revenue leaping to $4.7 billion from $3.8 billion in 2004.
Few nutritionists would dispute that an organic diet is beneficial to health--not only is it more nutrient-dense, but also it is free of chemicals and additives--but there is one problem. Although many people consider organic to be synonymous with guilt-free, it doesn't mean organic food won't cause weight gain. It's a common misconception that food allowed in any diet can be eaten in abundance, when on the contrary, eating too much of anything, organic or not, is a surefire way to get fat.
"There are as many ways to cut down on calories as there are foods out there," says Marlene Schwartz, the associate director of the Yale Rudd Center for Food Policy and Obesity. "My advice is to use nutritional common sense--maximize fruits and vegetables, limit the amount of processed foods and keep portion sizes reasonable."
While new diets are growing in popularity, there are plenty that retain their status as weight-loss icons. Some have even expanded and become large brands such as Nutrisystem (nasdaq: NTRI - news -people ), a company that delivers prepackaged low-glycemic meals to clients, and Weight Watchers (nyse: WTW - news - people ), the weight-loss giant that racked up more than $1.1 billion in sales last year.
The South Beach Diet also continues to grow in popularity. Since being released in April 2003, the book spent 37 weeks at No. 1 on The New York Times best-seller list and currently holds the No. 3 spot. The author of the book, Dr. Arthur Agatston, believes its success is due to the diet's basic principles: Eat good fats, nutrients and protein, and exercise. A theme that he says will continue to grow throughout the next few years because it is simple and flexible. "What we're starting to see for the future of diets is coming from more understanding of functional foods and nutrient value. Americans in the last 30 years have been walking around hungry all the time because they're eating white bread, potatoes and sugar. If you're eating nutritiously, the calories pretty much take care of themselves."