"Shame on you."

Irish singer Una Healy has responded to a cruel comment about her body on Instagram. The former Saturdays singer shared a gorgeous snap of herself post-workout and captioned it, "Hard work pays off." While many friends and fans complimented the picture, one social media user decided to leave a cruel comment. They simply wrote, "Belly button", and accompanied the message with a vomit face emoji. The troll may have thought that they'd get away with leaving the unkind comment, but Una herself saw it and called them out. She addressed them, writing, "shame on you." Other fans had Una's back, with one commenting: "It's a beautiful belly button." https://www.instagram.com/p/Ca5J5NENcuG/?utm_source=ig_embed Last year, Una used her platform to tell her followers that she had been diagnosed with Hashimoto's, an autoimmune disease. Hashimoto's causes the immune system to turn on the thyroid gland and can leave a person with a number of different side effects like fatigue, fertility issues, and weight gain, among others. The pop star learned she had the condition after losing her voice on tour. She told Canadian singer Emma Gryner: "I remember when I joined The Saturdays first, you probably hear it a lot on my early recordings, my voice is a lot huskier, now I do have a huskier tone that comes out sometimes, like a rasp. "I found it was happening more and more and I went in one day to demo a song we were doing with the girls and the producer went 'OK, can you do that again' and he looked really worried." She was subsequently examined by a doctor who encouraged her to get her thyroid checked. Una has since been put on thyroxine, medication she will have to take for the rest of her life, and thankfully, she has said that she feels "totally healthy and completely normal".