Hayden Panettiere became agoraphobic, experienced rapid weight gain after brother's sudden death

On a Sunday in February 2023, things drastically changed for actress Hayden Panettiere: her younger brother and fellow actor, Jansen Panettiere, was found dead in his New York apartment. He was only 28.

The family would later reveal he'd died from cardiomegaly (an enlarged heart), coupled with aortic valve complications.

Now, the "Bring It On: All or Nothing" actress is opening up for the first time about the loss of Jansen, revealing how his death impacted her not only mentally, but physically.

HAYDEN PANETTIERE AND FAMILY SHARE JANSEN'S CAUSE OF DEATH AT 28: 'UNTHINKABLE LOSS'

Hayden Panettiere and Jansen Panettiere in 2019. (Amanda Edwards)

"He was my only sibling, and he was my younger sibling and it was my job to protect him," Panettiere told People magazine for their new cover story. "When I lost him, I felt like I lost half of my soul."

"I remember saying to somebody — and it hadn't even been a year — and I was like, 'Don't ever, ever expect me to get over the loss of him.' Because, no matter how many years go by, he will always be beside me.

"I will always be heartbroken about it. I'll never be able to get over it," Panettiere, now 35, said.

In addition to acting, Jansen was also a talented artist. (James Devaney/WireImage)

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"Time does heal things, but time can also make you think differently and ask different questions and wonder different things and realize different things that you wish you'd never realized," she explained. 

"Even recently, when I see people make a big deal out of little things, and you know, God bless ‘em for wanting it perfect, but when something that massive has happened to you, you really learn to pick your fights and just not let the little things upset you. Because once something so, so horrific, so, so deep, so, I mean catastrophic happens in your life, there’s not much that can really rock you."

She was certainly rocked by Jansen's loss; Panettiere says her grief far surpassed anything visceral.

"When my little brother passed away, my body did something I've never really seen it do before, which was within days, I basically just like ballooned. Ballooned out," the actress shared of her unexpected weight gain. "Stress and cortisol running through your body can do that. I tried everything — everything unhealthy, everything healthy — didn't matter what I ate, didn't matter what I did. My body… it was like protecting itself, shielding itself from the world."

Jansen Panettiere and actress Hayden Panettiere in 2007.  (Amy Graves/WireImage/Getty Images)

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"I tried everything - everything unhealthy, everything healthy - didn't matter what I ate, didn't matter what I did. My body…it was like protecting itself, shielding itself from the world."

— Hayden Panettiere

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"I got to see these horrific paparazzi pictures of me coming out of his funeral, which happened in a very private place where we grew up, so it was shocking," she said. "I didn't even recognize myself…It was bringing out the agoraphobia in me as well. Which isn't something I've always struggled with."

According the Mayo Clinic, agoraphobia is an anxiety disorder that "involves fearing and avoiding places or situations that might cause panic and feelings of being trapped, helpless or embarrassed."

"I lived in sweatpants and t-shirts and things that swallowed me up and were not flattering on me. It took me so long to pick out an outfit that I felt comfortable enough in, to just leave the house, go meet up with my friends," she recalled. "And so it became like that really bad, destructive hamster wheel of like, ‘Do I feel good enough to go out? I don’t feel confident enough to, but if I don't go out and if I don't keep moving… I'm never gonna move away from looking like this.'"

"I lived in sweatpants and t-shirts and things that swallowed me up and were not flattering on me."

— Hayden Panettiere

"I became desperate. Because I wanted to keep working, but I didn't want to go and be miserable on set. And I didn't want to go to fittings and look at myself in the mirror and hate everything that I saw on myself," she said.

Hayden Panettiere attends the world premiere of Paramount's "Scream VI" at AMC Lincoln Square Theater on March 06, 2023 in New York City.  (Dimitrios Kambouris/Getty Images)

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Through the help of her publicist, who put her in touch with a personal trainer, Panettiere has been able to turn a corner.

"My body just started reacting, not just from the working out. It allowed me to release the stress, the high expectations I’d always put on myself," she said, which helped her confront her agoraphobia. "There’s nothing like looking in the mirror and feeling like you look good enough to walk out the door."