Hayden Panettiere Gained Weight and Became Agoraphobic From the 'Stress' of Brother Jansen's 2023 Death: 'I Just Ballooned Out'

Hayden Panettiere is detailing how the sudden death of her brother, Jansen, took a toll on her both mentally and physically.

In one of the actress' first interviews since her younger sibling suddenly died from an undiagnosed heart condition in February 2023, she revealed that the "stress and cortisol" going through her body at the time resulted in a significant weight gain.

"I just ballooned out," she recalled to a magazine. "I didn’t feel confident to put on clothes and get out of the house, but I also knew that I needed to get out and keep moving or I’d never stop looking and feeling this way."

"It became a destructive hamster wheel of, do I feel good enough to go out?" the blonde beauty, 35, explained, admitting she became agoraphobic.

Hayden eventually found a guiding light in personal trainer in Marnie Alton, and the two began to go on frequent walks together.

"These long, beautiful walks where we could vent and it would be this therapy session," the Nashville alum spilled. "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."

The star's confidence came back as she started dropping the extra pounds. "There’s nothing like looking in the mirror and feeling like you look good enough to walk out the door," she said.

While the Heroes actress — who is sober after struggling with substance abuse on and off for years — is now starting to feel like her old self again, she's still in the process of grieving her little brother.

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"He was my only sibling, and it was my job to protect him," she gushed of the actor, who was 28 at the time of his death. "When I lost him, I felt like I lost half of my soul."

"I will always be heartbroken about it," Hayden confessed. "I will never be able to get over it. No matter how many years go by, I will never get over his loss."

As OK! reported, Jansen also struggled with drug abuse, but it was confirmed that he died from an enlarged heart.

"Though it offers little solace, the Medical Examiner reported Jansen's sudden passing was due to cardiomegaly (enlarged heart), coupled with aortic valve complication," his family stated. "His charisma, warmth, compassion for others and his creative spirit will live forever in our hearts and in the hearts of all whom he encountered."

People interviewed Hayden.