The actress - who is returning in a reboot of Tracy Beaker this month - finished fourth in the BBC show with dance partner Vincent Simone, but says the sparkle was taken off the accomplishment thanks to the trolling.
Dani, 31, who was a size six when she performed on the show, told Radio Times how she was bombarded with abuse about her looks.
She said: 'I was like, "Holy moly, if I’m fat, God knows what other people must be thinking if they’re bigger than me!" That must be just horrible. I can think of things really logically and be like, obviously, I’m not fat, that’s ridiculous.
'This person, obviously, is just bored, or has something wrong with their life that they feel like this is the only way they can get some validation and I actually feel sorry for them.
'So I can kind of put it logically, I guess. But yeah, for kids it must be so hard.'
Now: 'I was like, "Holy moly, if I’m fat, God knows what other people must be thinking if they’re bigger than me!" That must be just horrible,' she said. 'I can think of things really logically and be like, obviously, I’m not fat, that’s ridiculous!'
Success? The actress finished fourth in the BBC show with dance partner Vincent Simone [pictured], but says the sparkle was taken off the accomplishment thanks to the trolling
Nasty! Dani, 31, who was a size six when she performed on the show, told Radio Times how she was bombarded with abuse about her looks
The star added that people are now 'a bit more open' about their mental health in the present days and that others were using their social media pages more responsibly.
The star impressed the judges during her time in the competition and ultimately reached the final -which was won by gymnast Louis Smith and Flavia Cacace.
Dani is preparing to reprise her iconic role as tearaway Tracey Beaker - with the BBC recently releasing a new spoiler ahead of the upcoming reboot -titled My Mum Tracy Beaker.
Dani, who played the former tearaway teen in the original 2002 series, will reprise the character who is now in her thirties.
In the reboot based on Jacqueline Wilson's 2018 book, Tracy is a single mother to 10-year-old daughter Jess, played by Emma Maggie Davies, as the duo try to 'scrape by financially'.
She's back! Dani will return to Tracy Beaker in February with the BBC releasing a new spoiler ahead of the upcoming reboot (pictured in show still with her on-screen daughter)
Yet their lives are transformed by Tracy's new rich footballer boyfriend, Sean Godfrey, played by Jordan Duvigneau.
Sean, who is recently retired and has always admired Tracy since they were young, wants to whisk the mother and daughter away to his lavish mansion.
But with things starting to go 'pear-shaped', it's up to Tracy's 10-year-old daughter Jess to save the day.
My Mum Tracy Beaker will also see original show regulars Lisa Coleman, who plays Tracy's foster mum Cam, Montanna Thompson, who plays Tracy's nemesis Justine Littlewood, and Ruth Gemmell, who plays Tracy's estranged mother Carly Beaker.
All grown up! In new show My Mum Tracy Beaker, Dani, 31, who played the former tearaway teen in the original 2002 series, will reprise the character who is now in her thirties (pictured with on-screen daughter Jess and footballer love interest Sean in show still)
Then and now: Dani began playing the iconic role of Tracy Beaker in 2002 when she was just 12-years-old
The reboot will be shown from the perspective of Jess and coincides with the 30th anniversary of Jacqueline Wilson's original 1991 book The Story Of Tracy Beaker.
Dani began playing the iconic role of Tracy Beaker in 2002 when she was just 12-years-old.
In October, the actress admitted she was nervous to return to the role that launched her acting career, especially as lockdown restrictions in Manchester meant she was had to stay away from her family.
Dani shares four-year-old Avarie-Belle Betsy with boyfriend Simon Brough, and tweeted that they would be apart for the duration of filming.