*First Lady Michelle Obama flew up 40 spots on this year’s Forbes magazine list of powerful women to claim the top spot, ending the four-year reign of German leader Angela Merkel as the magazine’s most influential woman in the world.

Ms. Obama’s quick track up the list was mirrored by that of her husband’s former rival and now secretary of state Hillary Clinton, who moved up from 36th place last year to crack the top 10, taking fifth place.

Merkel, who is struggling with a rocky second term in office, dropped to fourth place behind Kraft Foods CEO Irene Rosenfeld and talk show host and media mogul Oprah Winfrey.

In compiling this year’s list, the magazine said it opted to “look up and out into the broader culture.”

“Our assessment is based less on traditional titles and roles and more on creative influence and entrepreneurship.”

That could explain the presence of singers Lady Gaga and Beyonce Knowles in the top ten, at seventh and ninth places respectively, along with talk show host Ellen Degeneres, who took tenth place.

At number six was Indra Nooyi, PepsiCo’s chief executive and a perennial inclusion on the list, who fell three places from last year’s rankings. Rounding out the top ten was Gail Kelly, chief executive of WestPac, who came in at number eight this year.

Forbes said Michelle Obama had been “a true change-maker since taking lodge in the White House in 2008,” citing her “Let’s Move!” campaign aimed at reducing childhood obesity.

“The first African-American in the post, she’s changed the face of the office (literally), and with consistently high approval ratings, she’s given a new generation of girls and women around the world a role model,” the magazine said.

(L-R) Lady Gaga, Oprah Winfrey, Hillary Clinton, Michelle Obama, Indra Nooyi

Female US politicians ranked high in this year’s list, with House of Representatives Speaker Nancy Pelosi in at number 11 and Republican former Alaska governor Sarah Palin making number 16.

Female US Supreme Court Justices Sonia Sotomayor (19), Elena Kagan (25) and Ruth Bader Ginsberg (31) made appearances, as did British Queen Elizabeth II (41), athlete Serena Williams (55) and Costa Rican President Laura Chinchilla (83).

View the full list here.