Duchess Kate, who finds it "very hard to eat", is undergoing hypnotherapy to cure her morning sickness.
The 31-year-old royal - expending her first child with husband Prince William in July - has taken up the subconscious therapy to help overcome "negative thoughts".
A friend of Duchess Catherine - known as Kate Middleton prior to her marriage - Jessica Hay told Australia's New Idea magazine: "[Kate] still looks at food and feels nauseous, [she's been plagued with] that feeling you have when you've had food poisoning and your stomach's shrunk.
"She finds it very hard to eat a full meal and gets full very quickly. The hypnotherapy is taking away any negative thoughts connected with food from the morning sickness, and replacing them with cravings for healthy, nutritious food."
According to Hay, the Duchess has been eating wholesome meals and snacks consisting of food such as avacadoes, berries, oatmeal and broccoli while surrounding herself with her loved ones.
Hay added: "All in all, Catherine's very happy. With so much family around her and William, they're starting to enjoy the pregnancy after such a traumatic start."
Kate has also taken up Pilates to keep fit during her pregnancy and is keeping a regular schedule of three workout sessions a week, as well as catching up on sleep whenever she can.
A source said previously: "She's been doing it three times a week because she feels it's the best type of exercise for her - unlike yoga, she can focus on specific areas of her body."
"Kate's been looking after herself by making sure she gets eight to 10 hours of sleep a night."