In recent months, Scarlett has lost a dramatic amount of weight by eating healthily and exercising, and she is almost unrecognisable in her latest photo.
Snapped in the mirror following a workout, Scarlett can be seen with her hair piled on top of her head while wearing shorts, a T-shirt and trainers.
One fan gushed: "Tell us how you did it - well done!" Another added: "You look so well, you should be so proud!"
However, some of Scarlett's followers feel she has taken the diet a little too far. One commented: "Ohhh! Don't lose any more weight!" This was followed by another fan, saying: "You're doing great but you're looking a little too skinny."
Scarlett hasn't replied to her concerned fans on social media. Reveal has contacted Scarlett's rep.
In August, Scarlett revealed how she had lost an impressive two stone after embarking on a new fitness regime.
She had previously revealed it was sparked by a visit to the doctor, telling Closer magazine: "I knew I was overweight but when I went to the doctor for a check up, she said, 'You're not overweight, you're obese.' I was really shocked. I almost cried."