Katharine McPhee

McPhee was born in Los Angeles, California. Her father, Daniel McPhee, was a television producer. Her mother, Peisha (née Burch) McPhee, has been a vocal coach on American Idol since 2011. The family moved to the Sherman Oaks neighborhood of Los Angeles when she was 12 years old. Peisha McPhee recognized her daughter's musical talent and decided to train her. McPhee's older sister, Adriana, has been a vocal coach on American Idol since 2012. McPhee is of English, Irish, Scottish, and German descent.

She attended Boston Conservatory for three semesters, majoring in musical theatre. She left college before graduation on the advice of her manager, and returned to Los Angeles to try out for television pilots. McPhee was cast (during the time she had dropped out of college and was auditioning in Los Angeles) in a mall-based MTV soap opera pilot, You Are Here, playing the older sister of a more popular younger sister. MTV never aired the pilot and did not pick up the series.

In March 2005, McPhee starred as Annie Oakley in a Cabrillo Music Theater production of the musical Annie Get Your Gun. McPhee was nominated for a Los Angeles Stage Ovation Award in the category of "Lead Actress in a Musical". McPhee had a small role as Paramount Girl in the 2007 musical film Crazy, based on the life of Hank Garland. McPhee filmed the role in early 2005, before she auditioned for American Idol.

McPhee has struggled with eating disorders. She told People that at age 13, she began starving herself and exercising compulsively, and at age 17, became bulimic. McPhee gained weight in college due to her bingeing. After seven years of illness, she finally entered a three-month rehabilitation program after successfully passing her American Idol audition; her rehab stint ended just before the Idol semifinals started in February 2006.

She told Teen Vogue in May 2007, "I eat whatever I crave—I'm just really careful about portions." McPhee and her sister appeared on the debut of The Dr. Keith Ablow Show on September 18, 2006, to discuss her struggles with bulimia and her childhood fear of her father.