Kate Middleton has been known to be very active since her university days. Many individuals attributed this to her lean and slim figure.

However, it was recently claimed that her active lifestyle is not the only thing that makes up her diet completely. As revealed, the Duchess also follows strict diet rules, which were deemed as a secret until today.

According to Express UK, the Duchess of Cambridge utilizes "unusual" diet methods to maintain her appearance and figure. It was even noted that one of these methods is a popular diet that has been followed by celebrities like Jennifer Lopez and Giselle Bundchen.

This diet is called the Dukan method. It was reportedly designed by a French nutritionist and dietitian, Pierre Dukan. He proposed the diet as a "healthy eating plan" based on how primitive hunters eat.

It consists of only 100 foods. 72 of which are sourced from animals and the remaining 28 are plant-based. In this diet, it was said that foods can be eaten at any amount as long as the foods are included in the list.

The sources claimed that Kate Middleton used this specific diet before her wedding. It was shared that this method allowed her to lose two wedding dress sizes.

But, when she is not doing the said strict diet, the Duchess of Cambridge reportedly sticks to eating raw foods. Aside from intending to maintain her figure, it was said that this also helps her to improve her hair and skin health.

As per Good Housekeeping, several insiders revealed that Kate Middleton loves to prepare the food for her family, despite having their own chef inside the Kensington Palace. It was said that her love for cooking and preparing meals can be accounted for her background as the Middleton family reportedly loves to cook and prepare foods.

For breakfast, the Duchess reportedly always makes a smoothie. The usual ingredients were said to be blueberries, spirulina, kale, match, cilantro, romaine, and spinach.

As for lunch, it was said that Kate prefers meals that are "rich in antioxidants." So, these meals largely focus on bowls of salads and "seasonal fruits."

At the end of the day, roast chicken is the most popular meal served for the Cambridge family. It was said that this is Prince William's favorite.

But, amid all the healthy foods and diet rules, Kate Middleton reportedly has "one vice" that she is partial to every night. It was said that she "indulges" into a glass of white wine, which is basically deemed as a treat for herself after a busy day.