Sang Tan/AP Photo

Kate Middleton and her husband, Britain's Prince William, visited a London charity for homeless youth on Wednesday.

Middleton - who wore an olive jersey dress from designer Ralph Lauren that was nearly sold out within hours after  she appeared in it - looked sleek. A black belt accentuated her thin waist and flat stomach, dampening the feverish media speculation that the Duchess of Cambridge could be pregnant.

William and his brother, Prince Harry, both were introduced to the charity by their late mother, Princess Diana. William now serves as its patron.

The Duke and Duchess joined Centrepoint youth in a healthy cooking lesson - the pair made low-fat mince piece and gingerbread, attended a talent show and watched a group session of a work preparedness program.

During their visit, the royal couple teased each other and appeared affectionate, according to several reports.

William, who was dressed in casual clothes, even danced alongside one of Centrepoint's residents. His playful antics brought a smile to Middleton's face.

The couple will reportedly spend Christmas weekend and Christmas Day with the entire royal family at Sandringham Manor, the Norfolk, England, retreat of William's grandmother, Queen Elizabeth II.