Brian Austin Greenis opening up about his “rough” battle with the inflammatory bowel disease known asulcerative colitis.

The actor, 48,appeared onGood Morning AmericaThursday morning, where he spoke alongside pregnant girlfriendSharna Burgessabout his recent health issues.

Noting that he has “dealt with ulcerative colitis a few times,” Green called dealing with the illness “a real rough experience.”

“Sharna had never experienced it at all,” he continued, before Burgess, 36, chimed in, adding, “I didn’t realize how debilitating it was until I saw him and watched weight drop off him.”

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As theBeverly Hills, 90210alum revealed that he “lost like 20 lbs.,” Burgess said that symptoms of the illness made her “scared,” given that she had no experience dealing with something like it the past.

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Brian Austen Green Says He Lost 20 lbs. During ‘Rough’ Ulcerative Colitis Battle on GMA

“Not having experienced this type of thing before, and still learning, I was supportive and loving and [like], ‘I’m here for you,’ and internally fearful for how long does this go on for?” she said.

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Brian Austin Green

Green then noted that he has revamped his diet in an effort to better live with the disease.

“I try and avoid gluten and dairy as much as possible,” he said during hisGMAchat. “It’s really just dietary, like, as long as I can keep things within my system that my body doesn’t think I’m poisoning it with, then it doesn’t fight back.”

He added: “I would eat food, and literally it was like, my body didn’t process any of that. So then, when you start playing catch up with, like, staying on top of being hydrated enough, that’s such a battle.”

Ulcerative colitis is “an inflammatory bowel disease (IBD) that causes inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum,” according to theMayo Clinic.

The condition can develop at any age, but the disease is more likely to develop in people between the ages of 15 and 30, according toNational Institute of Diabetes and Digestive and Kidney Diseases.

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Greenfirst revealed that he had been suffering from ulcerative colitisin a candidInstagram videopost last month. “Hey everybody, so I disappeared from Instagram for a while. I had ulcerative colitis for about six, six-and-a-half weeks, which wasn’t very fun,” he said at the time. “Horrible timing.”

“I always knew I wanted to have kids because that was a dealbreaker for me,” Burgess said onGMA. “One of the things I fell in love with him about was watching him be a dad and the way he parents. I thought, ‘It would be so incredible to raise a child with him.’ "

Good Morning Americaairs weekdays (starting at 8 a.m. ET) on ABC.

source: people.com