Princess Beatrice’s nutritionist Gabriela Peacock has written her first nutritional wellness book, sharing healthy eating tips.

Peacock believes that you can have huge results even with the smallest of changes in your diet. She told PEOPLE, “Biochemistry is so powerful — you can really change someone’s well-being in just a week,” but “it has to be easy otherwise it’s not sustainable.”

In her new book “2 Weeks to Feeling Great,” Peacock advocates intermittent fasting, supplements and minor tweaks to what you eat and when you eat it.

Beatrice, who is a huge fan of Peacock, has even endorsed the new book, stating that its principles “are effective and realistic guidelines to follow no matter what you are doing in the day.”

Peacock said Beatrice, who announced her pregnancy in June, has never looked better, adding, “She looks amazing, just super happy, and they are all fantastic — it’s great news!”

The nutritionist has not put the princess on a special maternity diet regimen, but she said that “like all friends, I try and be helpful, no matter what kind life changes they go through,” adding, “I talk about nutrition, all the time, so I think it slightly rubs off on my friends!”

Peacock went on to say, “There is so much [information about nutrition out there], it’s a minefield. With COVID, it showed everyone how important it is for your body to be functioning at its best.”

Appreciating intermittent fasting, she said it has been scientifically proven not only for weight loss but also for others. She said, “It’s anti-inflammatory, it prevents cardiovascular diseases and it’s anti-aging, which is fantastic. And it really works for my clients’ lifestyle.”

Furthermore, Peacock said she is a firm believer in trying to balance your blood sugar levels. She said, “Never eat fruit on an empty stomach because it will spike your blood sugar levels, as will coffee. It’s fine to have them, but eat with a portion of protein too.”

She encourages people to have protein-based snacks such as yogurt with nuts and seeds, nut butter and apples or a protein bar for an afternoon snack. The story was published on PEOPLE.