While fans have loved her cheeky approach to presenting the show, the 42-year-old showed a more serious side to her on Wednesday when she shared news of her ongoing health battle publicly for the first time.
WATCH: Rhiannon Ally reveals secret health battle to co-stars live on-air
According to the Mayo Clinic, ulcerative colitis is an inflammatory bowel disease (IBD) that causes inflammation and ulcers (sores) in your digestive tract.
Speaking to DeMarco and Jennifer about the effects of Crohn's disease and colitis, the 42-year-old said: "You know, this is not something that I've ever talked about publicly, but I actually have ulcerative colitis and I've had to make so many changes to my diet, exercise routine."
Rhiannon shared her diagnosis publicly on GMA3
She added: "You really have to find a way to mesh it. It's very hard. Different foods affect people differently, it's really amazing."
Rhiannon made her first appearance on GMA3 on Tuesday opposite DeMarco, who is filling in for T.J. Holmes.
Amy and T.J. are currently on hiatus from their gig on GMA3 while the network decides how to handle their relationship revelation.
Rhiannon is filling in for Amy amid news of her relationship with T.J.
ABC News President Kim Goodwin announced the company's decision in an editorial call last week and said it wasn't an easy decision to make.
Kim confirmed that the two hosts would be taken off the air while they figure out the next stages and that while Amy and T.J. were off, Gio Benitez and Stephanie Ramos would be keeping their seats warm.
They did so for the first week and now there are new anchors filling in for the duo. It has not been revealed when the pair will be back - or how long the hiatus will last.
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