Thin may be in, but the lack of fat in the face can lead to a markedly aged appearance. And losing weight ages those over 40 even more rapidly.
According to AsiaOne, this was local plastic surgeon Woffles Wu's take on Hollywood star Renee Zellweger's "new" look.
When the 45-year-old actress walked the red carpet at the Elle Women In Hollywood Awards in Beverly Hills on Monday, she surprised everyone with an almost unrecognisable face.
Some plastic surgeons guessed that the actress, known for the Bridget Jones movies, might have had Botox, fillers, brow lift, facelift and a nose job.
Dr Lyle Back, a plastic surgeon in Philadelphia, a city in north-eastern Pennsylvania, told Hollywood Life: "I think she actually looks much nicer now.
"She had an excellent facelift which has made her face much less puffy, rectangular and masculine appearing.
"Her face is more oval, elegant and feminine without an 'over-pulled' look. She also had her eyes nicely done, losing the heavy, tired look.
"A well-designed, finessed nasal reshaping created a nice balance with the rest of her."
But Zellweger has denied having had plastic surgery and called the speculation "silly".
Dr Wu told The New Paper that the actress likely only had blepharoplasty - removing excess fat from her upper eyelids.
Her startling new look, he felt, was a result of extreme dieting.
He said: "Renee has a lot of wrinkles. So I doubt that she had Botox or fillers done.
"You know when a person suddenly has an illness like cancer and they start to look different? It is the same when someone experiences extreme weight loss.
"My guess is that Renee is on some fad diet which has caused her to lose a lot of the fat in her face."
Dr Wu said he is familiar with this beauty paradox and has always advised his patients not to lose too much weight. To him, when a person is over 40, losing 2kg can age them as much as five years.
So how does one overcome the paradox? He said that Botox and fillers can help people who want to be slim have plumped-up faces.
As for Zellweger's upper eyelids looking "less puffy" and her eyebrows now being much closer to her eyes, Dr Wu is convinced that she has had blepharoplasty.
"If you look at her eyes, they have a hollowed-out look. The result of removing excess fat in the upper eyelids is that the eyes tend to look sunken.
"So she looks older."
In Singapore, blepharoplasty costs about $7,000.
Zellweger's fans have rallied to defend her.
Many felt that she deserves to be left alone to "age gracefully".