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Just a few days after Kayla Itsines shared a photo of her stretch marks with her 7.1 million followers on Instagram, the fitness star posted about another common body reality we don't often see on social media: thinning hair.

In the caption to a mirror selfie with her hair up in a long, flowing pony, Itsines revealed that she's wearing clip-in extensions: “My natural hair is actually super short. I have genetically really thin hair," she wrote, adding that her grandmother and her mom have thin hair as well, and that there is a family history of female pattern baldness. "I can see my hair getting thinner and thinner the older I get."

RELATED: 21 REASONS WHY YOU'RE LOSING YOUR HAIR

Female pattern baldness is the most common cause of hair loss in women. It occurs when hair follicles shrink over time; as a result, strands of hair don't grow as long or as thick as before, and eventually stop growing altogether. The first sign is usually a widening part; and the hair on the top and crown of the scalp gets noticeably thinner. But female pattern baldness rarely progresses to total baldness.

“If you come from a family where women started to have hair loss at a certain age, then you might be more prone to it,” Marc Glashofer, MD, a dermatologist in New York City, told Health in a prior interview. Some women may benefit from using minoxidil (Rogaine), which is available over-the-counter and approved for hereditary hair loss, he says. It can help grow hair, or at least maintain the hair you have.

RELATED: 7 WAYS TO REGROW THINNING HAIR, ACCORDING TO DERMATOLOGISTS

Itsines admitted that it has taken some time to come to terms with her thinning hair. Though she's still "super conscious" about it, she says, "I am at peace with it and I will not let it rule my life."

Instead of obsessing about what her locks will look like down the road, Itsines focuses on staying healthy and happy in the present—and she encourages anyone who might be struggling with a similar issue to join her: “This is definitely a really difficult thing to do and I know from first hand experience, but it is definitely worth it and you have NOTHING to be shy about, be PROUD."

This article originally appeared on Health.com