NEWPORT BEACH, CALIFORNIA: Heather Rae El Moussa is shedding light on the challenges she faced upon discovering her diagnosis of Hashimoto's disease.

Speaking to People, the 'Selling Sunset' alum discussed the "shocking" revelation of the autoimmune disorder.

What is Hashimoto's disease?

According to the National Institutes of Health, Hashimoto’s disease is an autoimmune disorder in which the immune system attacks the thyroid gland.

The disease causes symptoms like slowed heart rate, thinning hair, fatigue, joint and muscle pain, weight gain, dry skin, and more.

Heather Rae El Moussa talks about 'hardest' part of learning about her disease

Reflecting on the "hardest" part of learning about her disease, El Moussa said, "When I found out that it was an autoimmune disease, I was definitely shocked because I've always been a very healthy person."

"So it has not been easy to get my levels right and to feel good again. Just doing the blood work, that was the hardest thing for me,” she added.

"I don't like giving blood and I was having to do blood work every 10 days. But I knew I had good people around me to help me get better," continued.

Heather Rae El Moussa says her 'lifestyle is very healthy'

The reality star received her Hashimoto's diagnosis four months after she welcomed her son Tristan with her husband Tarek El Moussa.

“After I had Tristan, I just felt really tired, really run down, barely any energy, just hard to get up in the mornings, and just exhausted throughout the day," said El Moussa.

"But I just thought it was being a new mom and being up all the time with a baby and just nonstop with a newborn," she added.

In her treatment plan, the 'Flipping El Moussas' star was prescribed Synthroid, and she made significant changes to her lifestyle to address the condition.

"I cut out gluten and I cut out soy, which is not easy for a vegan,” she shared, adding "I go on a lot of walks, I eat very clean, I drink a lot of water, I take electrolytes, so overall my lifestyle is very healthy."

"You have to be more diligent with what I eat. I eat a lot at home. I really try to cut it out as much as possible," she continued.

"I'm finally starting to feel better and I feel like my levels are doing well. I'm about to be getting blood work next week to see where I'm at," El Moussa said of the positive impact of the changes.