Posing in a striped swimsuit, the 17-year-old revealed her slender figure with a mirror selfie, clearly having shed the pounds since her stint on the show.
Ella previously said she wouldn't lose weight to help her career - having dropped to a dangerous weight when she was just 15.
[ Josie Gibson confesses she's terrified of gaining weight after her boob job ]
She said: "If someone told me to lose weight now, I’d take no notice. My music isn’t going to sound any different whether I look like a bean pole or Mr Blobby."
But despite saying she stays ahead of the pressure, there's no denying she has lost some weight since last year.
Thankfully, it doesn't sound like Ella has embarked on any extreme diets, instead enjoying the various foody treats in LA while recording her album.
She tweeted: "In n out burger or Californian smoothie?? Mmm help me Guys?!"
Ella became the victim of Twitter trolls during last year's X Factor live shows, with one user labelling her an "ugly fat ******".
The comments led to the star revealing that she has previously struggled with keeping her weight at a healthy level for years.
She told the Daily Mail: "There is pressure out there on young women. You look around you, in magazines and you think, 'Should I be skinny? Do I need to go on a diet?'
"It’s easy to fall into that trap. Last year I was very body-conscious. I went completely the other way and I went underweight at a certain point.
"From the weight I am now, I lost about two-and-a-half stone. Now I’ve found the right balance and I’m happy. I’m a normal-sized girl.
"I’ll never be a size zero, that’s just not going to happen but I’m simply going to be myself and I hope people will accept me for who I am."
[ Christina Aguilera shows off her amazing weight loss in before and after pictures ]
[ Pregnant Kim Kardashian faces pressure from Kris Jenner to sign Weight Watchers weight loss deal ]