Model Molly Sims talks baby weight, thyroid problem

LOS ANGELES (KGO) -- A lot of new moms find it challenging to lose the weight they gained when they were pregnant, even supermodel moms. Molly Sims says she went to extremes in the gym to try and drop 72 pounds after her son was born.

The supermodel turned super mom wondered if she'd ever get that killer body back.

"I stepped on the scale," she said. "I actually have a picture of my scale and my feet and it was 204 pounds."

But it turns out, a doctor made the difference. And we're not talking about a plastic surgeon.

Sims says she was diagnosed with a condition that affected her weight and made her neck as thick as a football player's. And no amount of time on the treadmill was going to fix it.

Sims: "I would work out for an hour and 45 minutes, an hour and fifty."

Reporter: "So you were working out?"

Sims: "I wore a trash bag."

Reporter: "You wore a trash bag?"

Sims: "Uh huh. To sweat more."

Reporter: "Like, you were determined to get this weight off?"

Sims: "Turn on the heat. I had a corset on."

Exercise wasn't working. She also tried acupuncture and went to a Chinese herbalist.

Her baby bulge wouldn't budge. So she made an appointment with her doctor.

"He was like uh oh, something's wrong with your thyroid," Sims said. "My neck was huge. Literally huge."

Molly says she was diagnosed with thyroiditis.

"It can affect your mood," said Dr. Rashel Tahzib. "The way you are interacting with your family, your weight, your metabolism, and it can increase pregnancy related complications."

Dr. Tahzib says thyroid problems can be triggered during pregnancy and can lead to serious problems if left untreated.

Sims started taking medicine to balance her hormones and finally she lost the weight.

"My neck slowly started going down," she said. "It took about six months, eight months. It took a year."

Sims says she and her husband are now trying for baby number two.

According to Web MD, about five percent of women who do not have a history of thyroid disease develop the condition after having a baby.