Presley and more celeb transformations

At 46, Lisa Marie Presley is feeling 16 again. Eating clean and organic has helped her to reach "the weight I was at when I was a teenager," she tells People magazine. Presley, the daughter of Elvis Presley, was inspired to get fit because of her father's family history of shorter life spans. "I didn't know where I would land," she said. "So I said, 'OK, I'm going to play it safe and try to be as healthy as I can be.' "

Tom Arnold has lost about 90 pounds since his first child was born last year, and he was looking quite thin at this year's South by Southwest festival, left. He'd actually lost the same amount of weight before but regained it when he didn't maintain healthier habits. After his son was born, he knew he needed to make a lasting change. "I saw that little baby and I thought, 'I gotta stay alive for as long as possible,' " Arnold said in January. "That's a lifelong commitment."

Jessica Simpson shows off a supersvelte look in a Weight Watchers ad released in February. "I was so insecure -- I couldn't even believe what I weighed," Simpson told "Good Morning America." The singer/fashion mogul says she is feeling better than ever since giving birth to her second child in June.

Christina Aguilera turned heads on the American Music Awards' red carpet for two years in a row. At the awards ceremony in 2013, Aguilera surprised onlookers by arriving in a skin-tight white gown with revealing cutouts, displaying a much different look than her voluptuous appearance at the 2012 event.

At the 2013 CMA Awards, singer Miranda Lambert revealed a slimmer physique. Apparently, her fit frame is courtesy of personal trainer Bill Crutchfield: "Hey @CrutchCamp," Lambert tweeted November 7. "I got some compliments last night thanks to you!"

Chaz Bono told People in April 2013 that he had lost 60 pounds since appearing on season 13 of "Dancing With the Stars." "Diets don't work," he told the magazine. "You just have to change what you eat, and I have." Bono is pictured arriving at the GLAAD Media Awards in April 2010, left, and in April 2013.

There's no way Marissa Jaret Winokur could play "Hairspray's" zaftig Tracy Turnblad these days. The Tony-award winning actress dropped 60 pounds in 2012.

Jennie Garth slimmed down after splitting with husband Peter Facinelli in 2012.

Lisa Lampanelli said she underwent surgery to help her shed 80 pounds and give her a new look.

From thong to thin: Matthew McConaughey reportedly dropped 40 pounds for a role in "The Dallas Buyers Club," and the transformation was startling on the "Magic Mike" star.

Paula Deen announced in June 2012 that she lost 30 pounds over a six-month period after she was diagnosed with Type 2 diabetes. These days, she is looking slimmer than ever.