Brian Austin Green is not fighting his battle with ulcerative colitis alone.

The 90210‘s pregnant girlfriend Sharna Burgess was by his side to support him during a May 19 appearance on Good Morning America, where he opened up about how his diagnosis has affected his health after he suffered from an intense flare-up last month that lasted six-and-a-half weeks. 

“I’ve dealt with ulcerative colitis a few times,” he said. “It’s a real rough experience. And Sharna had never experienced it at all.”

The Dancing With the Stars pro said she “didn’t realize how debilitating it was until I saw him and I watched weight drop off him,” as Brian chimed in, saying he “lost like 20 pounds.”

Though there is no cure for ulcerative colitis—a chronic inflammatory bowel disease that creates inflammation and ulcers in the inner lining of the large intestine—Brian said that he is managing the illness by avoiding dairy and gluten. The new dietary restrictions have helped the Terminator actor ease the symptoms, which can include rectal bleeding, abdominal pain, diarrhea, cramping, fatigue and weight loss.