Molly Sims, the American swimsuit model who has appeared on the cover of Sports Illustrated, gives new moms advice about losing baby weight. After the blond beauty icon had her healthy baby boy, Brooks Alan, in June 2012, she says she had a long road ahead of her.

“I would workout for an hour and 45 minutes, an hour and 50 [minutes],” Sims said

In an effort to lose exercise-resistant fat, she wore a corset, tried acupuncture, went to a Chinese herbalist, and wore a trash bag to induce more sweat while she exercised, which is a common practice among wrestlers who try to cut weight right before weight in. However, none of these tricks of the trade were working for Sims, who says she gained 72 pounds during her pregnancy and felt she would never get back to her regular pre-baby body weight again despite her efforts.

“My neck was….I looked like a football player,” Sims told ABC News.  “I kept asking people, I’m like, ‘I don’t feel right. Something’s wrong with me.’”

Sims couldn’t understand how she had gained so much weight, but moreover she had an innate feeling that something else was wrong. She followed up with her doctor and was greeted with a lot of backlash and passivity on her serious concern.

 “Oh, it’s your hormones.  Oh, you just had a baby.  Oh honey, don’t worry about it.  You’re in Hollywood and you’re putting so much pressure on yourself to lose weight,” Sims recalled of people’s reactions.

She continued to search for answers after she gave birth, and four months later her doctor finally gave her a definitive diagnosis: thyroiditis, which is the inflammation of the thyroid. The thyroid is a butterfly-shaped gland that sits at the base of the neck. This tiny gland that weighs less than an ounce, caused Sims to gain a significant amount of self-concerning weight and stress.

The thyroid secretes two main hormones, thyroxine (T-4) and triiodothyronine (T-3), that control the rate at which the body uses of fats and carbohydrates, and influence body temperature, heart rate, calcium regulation, and protein production. If the body is thrown off balance because of damage to the thyroid cells, an autoimmune disease, genetics, or after pregnancy, and other various unknown reasons; it can become inflamed.

Inflammation, or postpartum thyroiditis, can also cause an excess of T-4, which stores in the gland and leaks into the blood stream, according to Mayo Clinic. It creates discomfort and abnormal swelling of the neck, a symptom Sims couldn't allow to slide by untreated. Once Sims was diagnosed properly, she began taking medications to regulate her hormones.

"It's been difficult, I'm not going to lie,” Sims admitted to Us Weekly. “I've had to exercise and keep a very, very rigid diet. I mean, it's the hardest thing I've done -- and I've modeled since I was pretty much 21 years old!"

Weight loss took almost 13 to 14 months after her thyroiditis diagnosis. Although she says she found it difficult, she got it under control once she finally knew her gut intuition was completely right about there being something wrong.  

“My wish is that [women] don’t stop asking people what’s wrong,” said Sims. “I tell these women, I’m like, ‘If you think something’s wrong, ask a million people.’”

She contributed her road to recovery on her persistence and the important, yet often overlooked, practice of listening to one’s body for answers. An estimated 20 million Americans have some form of thyroid disease and up to 60 percent of those with the disease are unaware of their condition, according to the American Thyroid Association.

“Just don’t give up,” Sims encouraged.