Britain's Catherine, Duchess of Cambridge.

Is Kate, the Duchess of Cambridge, too thin?

This is the question royal watchers are asking as she and Prince William celebrate their first year of marriage tomorrow.

As Kate sheds weight, there are concerns in particular because of the history of weight problems suffered by William’s mother Princess Diana. According to some sources, Kate’s weight has dropped to 42kg.

“She looks malnourished. Her face appears gaunt. She looks tired,” nutrition expert Lisa DeFazio told Star magazine.

A month ago, both Hollywood Life and Life & Style reported that William was planning an “urgent intervention” to address his wife’s weight loss, which has been attributed to persistent exercise and calorie-counting.

A source told Hollywood Life that the prince was aware of his mother’s battle with bulimia, due to royal pressures.

However, Ingrid Seward, editor-in-chief of Majesty magazine said Kate’s “transformation into a highly regarded member of the royal family is nearly complete”.

“She is now the Duchess of Cambridge, a striking woman who is comfortable speaking in public, going to charity events.” – Pretoria News Weekend