Marilyn Sorensen of West Jordan set a lot of goals for herself since being chosen for the "Dr. Phil" TV show's The Ultimate Weight Loss Challenge last September.

One is to be able to ride the roller coaster at Lagoon. Years ago, she had to get off when they couldn't fit the safety latch over her body.

"My husband was just mortified because here we were, walking out in front of hundreds of strangers knowing I was too fat for the ride," Sorensen said.

The past five months have been another type of roller-coaster ride for the 29-year-old massage therapist, who weighed 348 pounds when selected to be part of Phil McGraw's weight-loss program. Sorensen has lost 47 pounds so far under the scrutiny of a national audience. The "Dr. Phil" show (airing locally at 3 p.m. on Ch. 4) runs occasional episodes showing the 13 participants' progress and pitfalls. The project will end when the season ends in May.

Sorensen's marital woes were also laid bare when she revealed that her husband, Jarryd, cheated on her, and she was afraid if she slimmed down she would leave him. That sparked a session on the couple's troubles, with McGraw dispensing his in-your-face style of advice.

She said she hadn't expected to comment on her marriage, but she's glad she did. "It just kind of came out," she said. "When Dr. Phil asks you questions, they're very pointed and very specific and you just have to go with whatever comes out."

She said since then her marriage has improved 100 percent.

"I was apprehensive at first about airing our dirty laundry, because, of course, your neighbors and family don't know everything that goes on behind closed doors," she said. "But for us I wouldn't change it at this point, because it has forced us to face hard issues and grow as a family."

On the show, McGraw accused Jarryd of trying to sabotage his wife's weight-loss efforts. Now, Marilyn said, he's her biggest supporter.

"They say you have to earn your way out of a divorce," said Jarryd, "and I can say honestly that I'm pretty much doing whatever it takes to make sure my marriage stays together and we stay together as a family."

But it's not easy to have your infidelity outed on national TV. "When she made that comment, it was a pretty big blow," said Jarryd, who was in the audience at the time. After the show aired, he was confronted by neighbors and friends who thought Marilyn should dump him.