Image Credit: Courtesy of Jeff Nippard/Instagram Stephanie Buttermore was a fitness influencer with a Ph.D. in cancer research, with her life ahead of her. Based on her social media profiles, the late 36-year-old was living a healthy life. But when she suddenly died in March 2026, fans wondered what had happened to her in her final days. Buttermore's fiancé, Jeff Nippard, a fellow fitness social media content creator, announced the news of her death in a heartwrenching Instagram post.