Fitness Influencer And Cancer Researcher Stephanie Buttermore Dies Suddenly At 36 As Fiancé Jeff Nippard Announces Devastating News

Fitness influencer and cancer researcher Stephanie Buttermore has died suddenly at the age of 36, leaving the online fitness community in shock.

The heartbreaking news was confirmed on Friday by the team of her fiancé, popular YouTuber Jeff Nippard, who shared an emotional statement across Instagram and YouTube describing the loss as occurring with “profound sorrow.”

The announcement described Buttermore’s passing as “sudden,” though no details about the cause of death have been made public.

“As many of you know, Stephanie meant the world to Jeff,” the statement read. “She will be remembered for her warmth and compassion, her love for her family, and her PhD research on ovarian cancer.”

Buttermore, who built a huge following online through her science-backed fitness content and candid discussions about body image, had amassed more than one million subscribers on YouTube. Meanwhile Nippard, a former professional bodybuilder and powerlifter who shares evidence-based training advice, commands an audience of more than eight million subscribers.

The couple had been together for roughly a decade and became engaged in 2022. Nippard most recently shared a photo of the pair together on Valentine’s Day, just weeks before the tragic announcement.

In a move reflecting the sensitivity of the moment, comments were disabled on posts announcing Buttermore’s death across Nippard’s social media platforms.

Nevertheless, fans and fellow influencers rushed to earlier posts to express their condolences.

Fitness personality Heidi Somers, widely known as Buff Bunny, wrote: “Heaven gained an amazing angel. Someone who cared so deeply for others. Praying for you Jeff and her family.”

Another follower commented: “I have followed Stephanie for years, what a beautiful soul. I am so sorry for your loss.”

Buttermore was widely admired not only for her fitness content but also for her academic work. She held a PhD and spent years researching ovarian cancer, a passion frequently highlighted by her supporters.

Online, she became especially well known for openly sharing her struggles with eating disorders, body image, and mental health, topics she discussed candidly with her audience.

Her popularity surged during her widely discussed “All In” challenge, where she dramatically increased her calorie intake — sometimes exceeding 10,000 calories per day — as part of a personal journey to restore her health and encourage body positivity among women.

The experiment drew millions of views and sparked conversations across the fitness world about nutrition, recovery from restrictive eating, and healthy weight gain.

Buttermore largely stepped away from social media in March 2024, explaining that her mental health had improved significantly since reducing her online presence.

Her fiancé’s most recent YouTube video, posted just last week, focused on body dysmorphia, a topic closely tied to the struggles Buttermore had spoken about throughout her career.

In their statement, Nippard’s team asked fans to respect the privacy of Buttermore’s loved ones during what they described as an incredibly difficult time.

For many in the fitness community, the loss marks the sudden end of a voice that blended scientific insight, vulnerability, and advocacy for healthier relationships with food and body image.