Pippa Middleton, whose real name is Philippa Charlotte Middleton, is getting married on May 20. She is marrying 41-year-old hedge fund manager James Matthews. Since she knows the world will be watching her, she wants to look flawless on her wedding day. The younger sister of Kate Middleton is quite active and works out at the gym often. She was spotted last Wednesday after taking a 75-minute Pilates class.

Pippa's diet

Pippa is reportedly on the Sirtfood diet that is making headlines because doctors and nutritionists say it is extremely dangerous.

The 33-year-old bride-to-be has been on this particular diet before. Apparently, she feels comfortable enough with it and its results to be on it again.

The Sirtfood diet

The Sirtfood diet is a very strict food plan that was designed by health consultants Aidan Goggins and Glen Matten. In their book, they contend that people who stick to their instructions can lose seven pounds in seven days. In essence, that's one pound for each day of the week. Foods are grouped together in the way Goggins and Matten suggest to help activate a person's skinny genes. The food plan includes all of a person's favorite rich foods, but the key is to know how to group them together.

Meal plan

The meal plan consists of two phases.

The first phase limits a person's calories to 1,000 per day for three days. In order to get the set amount of calories, dieters should drink three Sirtfood juices and one Sirtfood meal. During the second phase, 1,500 calories are permitted for the remainder of the week with two green juices and two full meals each day.

There are 20 specific foods that must be eaten because they are rich in polyphenols, the chemical that speeds up the body's metabolism which causes a person to burn fat faster.

Some of the foods that contain that chemical include apples, strawberries, blueberries, citrus fruits, parsley, capers, green tea, soy, turmeric, olive oil, red onions, kale, walnuts, chocolate, coffee, and red wine.

Experts explain the danger

Experts say diets like the Sirtfood diet don't work in the long run. Besides, they are dangerous.

Registered dietitian Brigitte Zeitlin related that most people usually burn out on diets like this because they’re starving themselves.

Nutritionist Laura Thomas told the Huffington Post that this diet is focused on drinking two or three juices a day. Thomas doesn't approve of drinking that many vegetable juices for meal replacements.

Whether you are getting married soon or want to lose weight rapidly for another reason, there are safer methods than the Sirtfood diet.