By ABBY ELLIN

Cookies? On a diet? Apparently so.

Just ask Christina Kane, who had tried many weight-loss programs with no success. Then she heard about Dr. Siegal’s Cookie Diet, which involves eating six prepackaged cookies a day plus one “real” meal - say, skinless chicken and steamed vegetables.

“I thought, ‘That diet looks so incredibly easy,’ ” said Ms. Kane, 43, a legal secretary in Washington, who started paying $56 a week for the prepackaged cookies in June, when she weighed 115 kilograms. Three months later, she was 18 kilos lighter. “If you can make it through the first week you’re in the clear,” she said.

Ms. Kane is one of an estimated 500,000 people who have lost weight on Dr. Sanford Siegal’s diet - at least according to Dr. Siegal. The gist of it is simple: Eat cookies and lose up to 4.5 kilograms a month. Or, in blunter terms: Consume a substance whose ingredients and nutritional value are somewhat vague and drop weight, because how can you not when you’re consuming only 800 to 1,000 calories a day?

Dr. Siegal’s diet isn’t new; it was created in 1975, but for years was only available to patients in his Miami medical practice and at other doctors’ practices that he supplied with cookies.

That changed in 2006 when he started CookieDiet.com. This year he began selling his cookies at stores . He expects 2009 revenues to be $18 million, up from $12 million in 2008.

Other companies have emerged: Smart for Life (six 105-calorie cookies a day; a 35-day kit costs $279); the Hollywood Cookie Diet (one 150-calorie cookie three to four times a day, plus a light dinner; $14 to $20 a box); and Soypal Cookies, marketed as “the most popular diet in Japan” (about 22 calories each; $49 a box).

However, critics of these diets contend that weight-loss plans centered on a diet of below 1,000 calories do not lead to long-lasting weight loss and can result in potassium deficiency, gallstones, heart palpitations, weakened kidney function and dizziness.

The cookie diet particularly concerns eating disorder activists, who have long criticized fad diets, such as the grapefruit diet . “Generally speaking, fad diets misinform the public and fuel a fire of continued curiosity with this dieting mentality, which we know gets us nowhere,” said Dr. Ovidio Bermudez, medical director of Laureate Eating Disorders Program in Tulsa, Oklahoma.

Despite such criticism, the cookie diet thrives. Richard Kayne, chief operations officer at Smart for Life, said he expected $82 million to $95 million in gross revenue this year, up from about $30 million last year.

Never mind that there are no clinical studies on any of the diets and that a key ingredient in Dr. Siegal’s cookies ? special amino acids, which supposedly curb appetite ? is known only to Dr. Siegal and his wife. “It’s the particular mixture of proteins that does the job,” he said.

Dr. Siegal says his product is nutritionally sound, but just to be safe, a seven-day supply of multivitamins comes with each weekly package .

Some nutritionists don’t think you should embark on the program at all. “The bottom line is that you can’t meet your nutritional needs in six cookies and one meal a day,” said Keri Gans, a registered dietitian in New York City. “It’s not possible.”


Diets based on cookies are gaining sales and skeptics. / TONY CENICOLA/THE NEW YORK TIMES