Updated May 01, 2014.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Cookie diets have basically one rule: Eat about 6 cookies a day and one small meal. That's it. Of course, who can resist a diet that starts out with "eat cookies...?"

What is a Cookie Diet?

A cookie diet is one of several diets available that have dieters eat pre-packaged cookies throughout the day and then have one small meal. This keeps the total calorie count very low (around 1,000 calories a day) to promote weight loss.

The cookies are purchased from the company for around $60 a week.

What are in Cookie Diet Cookies?

Good question. The "original" cookie diet by Dr. Sanford Siegal contains "secret ingredients" that are said to reduce appetite. These ingredients, according to the diet's website, are proteins that help you feel full.

Is A Cookie Diet Safe and Healthy?

It's hard to say, because the nutritional ingredients in the cookies are not known. But here's one thing that most nutritionists agree on: Eating 1,000 calories a day is not a healthy way to lose weight -- it's too few calories. You can't get the nutrients your body needs in that few calories. Some cookie diet plans try to counter this by including multivitamins with the cookies.

But Do Cookie Diets Work?

There are a good number of testimonials out there, but no scientific studies have proven whether cookie diets work. The key question is whether or not the cookie diet sets you up for a lifestyle of being at a healthy weight. It seems obvious (to me) that the cookie diet must be a temporary diet - it cannot be sustained for a lifetime (even people practicing calorie restriction for longevity eat more calories that this).

So, after a cookie diet, the dieters are still going to have to learn how to eat in the real world.

Should I Go On A Cookie Diet?

I can't answer that question. I recommend proceeding with caution and the advice of your doctor. Only eating 1,000 calories a day is an extreme strain on your body. You'll have to balance that with your need to lose weight, your history of dieting, and other health conditions that you might have. Of course, you can always alter the cookie diet to have more calories simply by adding a second meal of "real food." Talk to a nutritionist or physician to learn more.

How Can I Learn More About Cookie Diets?

Here are some links to the most popular cookie diets. Please keep in mind that these are marketing sites trying to sell you cookies:

• Dr. Siegal's Cookie Diet
• Smart For Life
• The Hollywood Cookie Diet

You can also read this piece from The New York Times on cookie diets.