Jennifer Hudson before and after 80-pound weight loss

jennifer-hudson-before-after.jpg"American Idol" alum turned Grammy and Oscar winner, Jennifer Hudson, stops by "The Oprah Winfrey Show" on Thursday (Feb. 10) to share her weight loss success story, and of course, plug Weight Watchers.

It's easy to peg her success as the result of a paid sponsorship and access to personal trainers and chefs, but Hudson disagrees, saying the results are all mental.

"I've cooked all my meals at home, when I work out I do what I like to do, I don't believe in overdoing myself," she explains. "It's all about self motivation because at the end of the day you can have all the money and all the personal trainers in the world, but if you don't have that mindset it's not possible... You have to do it for yourself."

Joining Hudson in the audience is her Weight Watchers leader, Liz, who was adamant about not disclosing Hudson's weight.

Liz claims that people shouldn't obsess over the number of pounds, saying "You've got to do what feels good to you. Who cares about the number?"

After being asked multiple times to share her weight loss, and repeatedly saying that she wants to tell, but isn't allowed -- Hudson finally blurts out, "I've lost 80 pounds! I'm sorry, I had to do it."

The now size six singer then received a standing ovation from Oprah herself, and the audience.

She admits that getting used to her new body is definitely taking some adjusting, and that mentally she's not quite in sync with her new look.

"I'll go in the store, and I'll pick up the extra larges or the bigger sizes... or I'll even pick up a medium and they're like 'That's too big,' and I'm like 'For who?'" she says of her current shopping days. "It takes a while to get adjusted to it mentally, my mind still hasn't caught up yet."

Hudson also opened up for the first time about her 2008 family tragedy, and debuted her latest single.
Photo/Video credit: Getty Images