Eating disorders devastated Sienna's body. This is what she wants people to know

It was the impending arrival of Sienna Wiltshire's niece that made her appreciate that life was worth living.

At the time, Ms Wiltshire's kidneys were failing and she was facing dialysis and the need for an organ transplant, the result of years of eating disorders that had ravaged her body.

Ms Wiltshire was diagnosed with type 1 diabetes at age 8 and when she entered high school - with all the stresses and comparisons against peers that time can bring - she realised that misusing her insulin could lead to weight loss, a disorder known colloquially as diabulimia.

But this had severe consequences: she got gallstones at 16 from rapid weight loss, and she developed serious nerve damage in her legs.

Several years later, the latter led to her unknowingly giving herself third-degree burns from a heater, and in a separate incident a blister that worsened to the point two toes had to be amputated.

It put an end to a lifetime of dancing for the former Wollongong High School of the Performing Arts student.

Surgery for the gallstones shocked her out of misusing insulin but in its stead came anorexia and bulimia - serious conditions that were no less damaging.

At 17, Ms Wiltshire suffered her first heart attack. A second followed at the age of 21, and the diabulimia returned.

More was to come: malnutrition resulted in her breaking her leg and most doctors wanted to amputate, but she ended up with an external fixation device for six months to keep the bones in place, using a wheelchair for that time.

In 2019, Ms Wiltshire was told her kidneys were failing and the following year she suffered a stroke that left her blind in one eye.

Faced with the news she needed dialysis and a transplant, she said she did not want to go through with it.

"I didn't want to do the treatment. I was too tired. I'd gone through too much in my time," Ms Wiltshire, now 29, said.

But then she learnt her sister was pregnant, and faced with her own mortality, Ms Wiltshire began noticing the beauty in life.

"When I was preparing myself to leave this world is when I really realised the power of it, if that makes sense," she said.

"So that's kind of what I try to tell people. Like there's so much more life, there's so much more to all of us.

"We have so many good days that we haven't lived yet, and it's not worth it just because you don't feel like you're enough - because I was always enough."

Ms Wiltshire, who now lives between Tarrawanna and the US, does not want to put her body through any more hardship; she has undergone 45 surgeries stemming from eating disorders, including a kidney and pancreas transplant a year ago.

She is now doing better than ever, but still maintains vigilance.

Australia's national charity supporting people with eating disorders and body image concerns, Butterfly, is preparing for a significant increase in demand for its services around the holiday period, especially with Christmas being such a food-centric celebration.

The organisation's head of communications and engagement, Melissa Wilton, said that while for many it was a time of joy to gather with loved ones over food, for people with an eating disorder it was a "heightened period of stress and pressure where the eating disorder noise grows louder than ever".

"At Butterfly our helpline counsellors are qualified mental health professionals with specialist training in eating disorders and body image, ready to help quiet the noise for anyone in need of support this holiday season," Ms Wilton said.

Butterfly reports there is also increased severity of eating disorders and more hospital admissions in summer, when people wear less clothes and there is more focus on the body.

Ms Wiltshire has experienced Christmas as a difficult time and recalls getting questions about how much she ate.

"When you're suffering something like an eating disorder, that is the last thing you want to hear, you don't want people to notice that anything's going on and when they're asking you those questions in front of an audience, it's so off putting and it turns you off the whole season," she said.

For others, she said, spending time with family, or Christmas not being a happy time of year could be triggers.

For Ms Wiltshire, being open and honest about how she is doing is a strategy she employs to keep on top of her health.

She tells her sister if she is not doing well with her eating, not feeling good about her weight, or feeling stressed, so that it doesn't get away from her.

"I feel like by telling someone and knowing that somebody's aware of what I'm doing, I'm protected," Ms Wiltshire said.

"It won't get too bad if someone else knows because they're going to step in and they're going to help me."

She has also had substantial therapy to address the issues she has faced.

For those whose loved ones are experiencing an eating disorder or body image challenges, Ms Wiltshire advises going gently.

"Just acceptance; love; be kind," she said.

"Don't approach things with any kind of aggression, just be kind about it. Let them come to you, because it's got to be a decision they make to speak about it."

Being kind is a message Ms Wiltshire wants everyone to take on board, especially at this time of year.

"I think the main message is just try to be a good person. You never understand how much that can change somebody's day," she said.

"I can't tell you how many times a stranger smiling at me or giving me a compliment is taking me back from the edge."