By Vanessa Brown and Lizza Gebilagin
She made headlines after shocking the world with her youthful looks.
But now 70-year-old grandmother-of-four Carolyn Hartz has been mocked online by dubious critics who claim a sugar-free diet can't be her only secret - and that she must have had surgery.
Appearing on UK breakfast show This Morning on Monday, the mum-of three revealed how she kept both age and weight off by banning the sweet stuff from her diet 28 years ago.
But not everyone was convinced that a sugar-free lifestyle was her only health hack.
"Her forehead can't even move," one viewer posted to Twitter.
"Who is this woman fooling?" another added.
"If she was gonna fool us all saying sugar-free makes her look young she could've made the surgery work look natural."
After finding out she was a pre-diabetic, Ms Hartz - author of Sugar Free Baking - switched to using a sugar alternative called xylitol, which her company now imports.
She hopes her lifestyle and recipes will inspire people to make the same dietary change she did.
"I could see what the effects of diabetes two was going to do to me," she said.
"When you're frightened of something you should change, and I did because I didn't want to be unhealthy."
Ms Hartz has been challenged in the past about whether a sugar-free diet was her only secret.
"You have to watch what you put it in your mouth, that's number one," she told news.com.au.
"And two, you have to move your legs."
Prior to her no-sugar diet, Ms Hartz didn't bat an eyelid at consuming cheesecake for breakfast, or an entire packet of biscuits in one sitting.
But rather than cut out the foods she loved for good, she made slight alterations to her baking methods to exclude sugar.
"At the end of that year I looked like a picture of health and my blood sugar levels were fine. I didn't have a problem anymore but by that stage I disliked living like that because I was depriving myself of all the things I loved," she says.
When she makes cakes at home, she cuts them into slices and freezes the portions.
"I don't leave it out because the temptation is too great to eat the whole thing."
Other than staying active and eating mindfully, Hartz meditates every day and goes for walks with her husband of 40 years.
She admits that she has had some cosmetic work done, but that's not the secret to looking so good.
"Yes I do get some maintenance done, but surgery is not the answer to a healthy wellbeing," she said.
She sleeps seven to eight hours per night and does charity work for the Brain Cancer Foundation. But, according to Hartz, the real secret to her health is her glass-half-full attitude.
Hartz points out that it doesn't mean life goes on without obstacles.
"I've always told my three children that life is not perfect. Everything won't go the way you want it to go, but that's fine.
"If you do have a challenge or a setback, get up. Go again. Because often that's the universe poking you in another direction. I'm a great believer in one door closes and another door opens.