Fat behinds ruin the lines of Calvin Klein, and Dior doesn't come in plus sizes. It's time for a diet! But which one? A new one pops up every day. We help you sort them out with Fad Diet du Jour.

The catchy name: Dr. Siegal's Cookie Diet, Hollywood Cookie Diet, Smart for LIfe

The story: In the 1970s, South Florida-based Dr. Sanford Siegal realized that "Hunger Wrecks Diets" and started to make appetite suppressant cookies for his patients who were trying to lose weight. The recipe is a secret, but it involves amino acids. You can order the cookies from his site, and there are also shakes and soups. It's a super-low calorie diet, around 800 calories a day, so you are only supposed to do it under the supervision of a doctor.

The scrawny celebrity dieter:
Mr. Madonna, Guy Ritchie

The anti-diet propaganda: Oh, this is a diet. That's totally explicit, and they advertise that many people lose 15 lb a month.

The regime: Eat six of these cookies throughout the day, drink eight glasses of liquid (coffee and tea are allowed) and finish up with a "sensible dinner" of 6 oz of fish or chicken and a cup of vegetables. That's it.

Our judgment: If you stick to it, you'll probably lose some weight because it's so low cal. But there's no recommended exercise plan, and most people will inevitably succumb to food boredom binging, so the pounds will probably return. Not a long-term solution, but might be worth talking to your doctor about it if you're struggling to jump start a serious weight loss program. Not for the diet dabbler.