What is TikTok's #hairtheory test and why is Gen Z obsessed with it?

#Hairtheory is the latest beauty trend taking over TikTok. (Getty Images)
#Hairtheory is the latest beauty trend taking over TikTok. (Getty Images)

For some people, the way they wear their hair is a pivotal part of their self-identity. For others, it’s simply a nuisance that sporadically (if it’s lucky) will get brushed. The way you wear your hair can change your whole appearance of course – and that’s the thought behind TikTok’s new #hairtheory trend.

Videos of the trend on the platform have amassed 35.3 million views so far, with Gen Z women displaying how different their faces look when they wear their hair in certain styles.

So what exactly is the #hairtheory trend? And which hairstyles will make you look younger and older?

TikTok’s #hairtheory trend explained

What is the #hairtheory trend? “‘Hair theory’ suggests that the way your hair is styled can transform the way you look, and that one particular style is ‘the one’,” explains celebrity hairstylist and Jerome Russell brand educator, Jason Collier.

The theory also argues that people could perceive you differently based on your hairstyle, Collier says. “This can be them treating you differently or talking to you differently.”

Gen Z are obsessed with the trend. While other generations have long ago figured out their signature hairstyle and know what works for them, the younger generation is just discovering how hair can change how you look.

Why does your hairstyle change how you look? “Like make-up placement, hair placement also plays a key part in what people notice when they look at our faces,” Collier says. “Depending on your face shape, specific hairstyles will make your face look unbalanced while others complement your face nicely.”

Portrait of Smiling Young Woman Wearing Earrings against White Background.
Wearing your hair in a ponytail can create the illusion of a different face shape. (Getty Images)

When you wear your hair up, it changes your face shape. “Anytime you pull your hair straight back, it keeps people's focus at eye level,” Collier says. “When you pull your hair up in a high ponytail, your hair is more on a diagonal in line with your cheekbones, drawing eyes upwards and instantly creating the illusion of a different face shape.”

Some hairstyles can make women look younger. Collier recommends a side-parting pixie cut, a layered and wavy bob, or an asymmetrical bob. “As women get older, hair becomes brittle and can thin, one way to add instant volume is by cutting it asymmetrically,” he adds.

Woman with pixie cut
Pixie cuts can be a youthful hair option. (Getty Images)

A pixie cut is a bold choice. It brings more attention to the face and cheekbones, which makes your face look young,” Collier explains.

Blunt cuts and thick fringes can age you. “A blunt bob is very bulky on most face shapes and doesn't frame the face. Instead, they draw attention to the eye and chin areas,” Collier says.

Woman with fringe looks at camera
A wispy fringe is less ageing than a blunt fringe. (Getty Images)

You should also avoid tight high ponytails. Whilst this is a great look for those wanting a bit of a lift, women over 40 should choose hairstyles that soften the facial features rather than tightening them,” Collier adds. Cooler and golden tones are also favourable over yellow blondes.

Watch: Lily Collins' hairstylist on 'Emily in Paris' says season 3 shows a hair 'evolution'