Vogue editor Anna Wintour once relied on a daily 4 p.m. coffee milkshake from a restaurant called Burger Heaven to get her through the afternoon, according to her former assistant Jill Demling.

Demling, who worked for Wintour from 1998 to 1999 and later booked celebrity covers for the magazine for nearly two decades, made the revelation on Amy Odell’s “Back Row” podcast. "At 4 o’clock, she always wanted her coffee milkshake, and we got that at Burger Heaven,” Demling recalled. “It was so good.”

The routine changed in 1999 when Condé Nast, Vogue's publisher, moved its offices from Madison Avenue to 4 Times Square. With Burger Heaven no longer nearby, Wintour switched to Starbucks Frappuccinos. Demling noted that Wintour was initially concerned about the lower calorie count of the Frappuccino compared to the Burger Heaven milkshake.

Demling also recounted the story of how Beyoncé landed her first cover for Vogue in April 2009. The planned cover star, Katherine Heigl, had to withdraw due to a film release date change. Demling suggested Beyoncé, who had a movie, "Obsessed," coming out. According to Demling, Wintour only agreed to the cover because of Beyoncé's film promotion.

By September 2015, however, Beyoncé had gained enough influence to decline an interview and insist on final approval of her photos for her cover shoot. Demling stated that at that point, Vogue likely needed Beyoncé more than she needed the magazine, and Beyoncé has maintained final image approval ever since. "No, she’s not okay with it,” Demling said of Wintour’s reaction to this arrangement, “But it’s Beyoncé."

Demling, who described herself as "talent first," also shared that she learned the importance of celebrity image control from Avril Lavigne. The singer reportedly turned down a Vogue shoot with photographer Steven Meisel at age 16 because she wanted to do her own signature hair and makeup, rather than use the photographer's preferred team.