A California woman who earned the title of the world's fattest woman last fall says she's dropped 100 lbs thanks to marathon sex sessions with her ex-husband, who said he couldn't resist her after she packed on the pounds.

Pauline Potter weighed in at 643 lbs in September when she earned the title of heaviest living woman from Guinness World Records.

It got to the point where the Sacramento woman couldn't go to the bathroom by herself - she had to have her teenage son help her.

Three years ago, she left her husband Alex. But after he saw her world record, he came back to visit her -- and they rekindled their relationship.

"I can't move much in bed, but I burn 500 calories a session - it's great exercise just jiggling around," Potter said Monday in an interview with the U.K. magazine, Closer.

"I hadn't had sex in three years, but we did it six times," she told the magazine of seeing Alex again. "He took charge as I couldn't move much, but he was so attentive."

She said they have marathon sex sessions when Alex comes to visit from Arizona, which has helped her lose weight -- something she's wanted to do since before being named the fattest woman.

"I sweat off loads of calories. I call it 'sexercise,'" she said. "I tell Alex he needs to visit more so he can help me shed the pounds quicker."

Alex said he enjoys their romps in the bedroom, but told the magazine they do have to be careful.

"Once, when she got on top, I couldn't breathe," he said.

When she won the title of world's heaviest woman, Potter said she hoped it would help spur her to a healthier life.

"I got in touch with Guinness World Records to start with because I was tired of being this size," she said at the time.

"I knew I was getting close to 700 (pounds), but I wanted to get my story out there so that a doctor or nutritionist could help me."