Who this diet is not for:

The basics: It's the diet that never stops being controversial. Critics have questioned how it could possibly promote weight loss. They've said it's dangerous for your heart. But independent studies published last year have disputed both those points, and millions of adherents swear by it. A recent Harris Poll found that 32 million Americans are on a high-protein, low-carbohydrate diet of some sort, with Atkins dominating the pack.

How it works: The diet was founded by Dr. Robert Atkins, who died last year after slipping on ice outside his Manhattan office. Its premise is that by metabolizing fat, rather than carbohydrates, as your primary energy source, you are less likely to gain weight.

Atkins said that the body naturally burns carbohydrates for fuel before turning to fat for energy. So to get your body to burn fat first, rather than carbohydrates, you need to cut the carbs from your diet. Atkins dieters get their energy from nutrient-dense, unprocessed foods instead - mostly proteins.

The Atkins plan has four phases: induction, ongoing weight loss, premaintenance and lifetime maintenance. The only restrictions are on the amount of carbohydrates you eat.

Limiting the carbs: In the induction phase, the first two weeks of the program, you can have as much protein, oils and fats as you want. That means you're allowed all the chicken, turkey, seafood, red meat and eggs, olive oil, butter and mayonnaise you can stomach.

You're limited to 20 grams of carbohydrates a day, though. They can come from leafy green vegetables, cheese, avocado and olives. No caffeine, alcohol, nuts or seeds are allowed. (There is a link to a sample induction menu below.)

The next three phases are more flexible, and let you gradually add more carbohydrates, such as asparagus and blueberries. During the second and third phases, you'll continue to lose weight, but at a slower rate than in the induction phase. The last phase lasts for life. By then you've figured out how many carbohydrates, and which ones, you can eat and still stay at your target weight.

About cholesterol: That people following Atkins have lost weight while increasing their levels of HDL, or "good" cholesterol, and lowering their levels of triglycerides - blood fats that can clog the heart's arteries - defies conventional wisdom about nutrition. Many doctors remain skeptical about its safety and why it seems to work for so many people.

Additional government studies measuring cholesterol levels and other important health markers over longer periods of time may resolve some of the controversy.

"Prior to this low-carbohydrate movement, managing your weight and health meant sacrificing and just not eating certain things or eating less," says Dr. Stuart Trager, chair of the Atkins Physicians Council. "Now it means eating differently. And eating differently gives people more choices and options and lets them take greater control of their health.

"Just knowing how many calories are in different foods always translated into the need to eat less. Improved carbohydrate awareness is extremely empowering and is helping many people who previously weren't able to take a role in lowering their weight to join this movement, shedding pounds and improving their cardiac risk factors."