Oprah Winfrey has purchased a 10 percent stake in the Weight Watchers diet company, and it’s sent the company’s stock soaring.

In speaking with NPR, Winfrey said that she didn’t even have to think about the investment. Weight Watchers asked, and she said yes.

“They called me and asked would I be interested in talking to them about establishing a relationship and I said, ‘Uh … sure.’ … I didn’t even think about it. … I’ve had many, many friends do Weight Watchers over the years and so we had a meeting, yes, and I said, well, I couldn’t do anything with them without trying the program first to see if that worked for me. So far I’ve lost about 14 pounds on it.”

I believe in the @weightwatchers program so much I decided to invest, join the Board, and partner in #wwfamily evolution.

— Oprah Winfrey (@Oprah) October 19, 2015

This is the kind of effect Oprah can have on your stock:

“It was not strictly a business decision. It was a personal decision that allowed me to make a smart business decision. I always lead with my heart because the truth is, my heart is my brand,” said Oprah.

#Excited to welcome @Oprah to our #wwfamily in a big way! Can't wait for all the goodness in store! http://t.co/XxqTdMw8Nt

— Weight Watchers (@WeightWatchers) October 19, 2015

“The good thing about picking Oprah Winfrey is that although she is very much a really strong media personality, lots of people still see her as being a very ordinary person, a person that has struggled with things like weight loss,” Neil Saunders, managing director of retail research firm Conlumino, told Reuters.

And that’s a good point. Oprah is a brand, and when it comes to struggles with weight, she has authenticity. Can Oprah help Weight Watchers improve its reach? If anyone can, it’s her.