But can you really have your cookie and eat it, too -- eat cookies and still lose weight?
Registered dietician and Early Show contributor Keri Glassman looked at four popular ones Tuesday.
She says all the cookie diets are basic meal replacement diets, with the cookies taking the place of one or more meals, the idea being that, "Hopefully, you're so satisfied from the cookies that you're not going to want to go and eat anything else until your sensible dinner."
"If you ate a few Chips Ahoy or a few Mrs. Fields and you didn't go overboard, and then you ate a reasonable dinner and kept your calories under control, technically, it's very similar to the cookie diets," Glassman added. "However, the cookie diets are either fortified with a little bit of fiber or protein or some vitamins and minerals to keep you full and add a little extra nutrition."
But are cookie diets nutritious?
"Better to eat real food. Much better to eat real food!" Glassman exclaimed.
She says cookie diets DO work -- in the short-run. Cutting calories leads to weight loss. But in the long-run, they're too short on calories to remain effective. You should be getting your vitamins and minerals from real food, she adds. And cookie diets don't teach how to approach eating properly, or how to deal with "emotional" eating.
Hollywood Cookie Diet
Four of the company's cookies a day, to replace breakfast and lunch, 150 calories each. Then
eat a sensible dinner. The cookies have added vitamins and minerals, some artificial sweetener, sugar, and protein fortification. The real reason this works when it does is the convenience and portion control.
Dr. Seigal's Cookie Diet
Has been around the longest, since about 1975. A bag a day of six 90 calorie cookies to replace breakfast and lunch. Then eat a sensible dinner. The company claims a proprietary blend of amino acids (the "building blocks" of protein) in the cookies helps curb hunger.
Smart for Life
Six 105-calorie cookies a day replace breakfast and lunch. The have a dinner of lean protein and vegetables. This one says it helps teach you to eat sensibly throughout the day but, Glassman says, you should really be learning this with food.
This one is from Japan and has been hugely popular there! It's different in that you eat sensible meals and replace your highest calorie meal (usually dinner) with a bag of seven cookies. They contain okara, a soy bi-product that expands in the stomach when consumed with liquid. So, you are supposed to "feed" the cookies fluid!