Kate Tolo got her first period at 13—an experience she says left her lying prostrate on the floor, debilitated by cramps and breaking out into a full-body sweat.
When she told her dad why she was home from school early, she remembers him saying, “We don’t talk about that female stuff.” Then he walked away.
For most of her teenage years, that was how Tolo thought about her period—as something “you just didn’t talk about.” When she was in her early twenties and experienced extreme pain while defecating, sending her to the emergency room, a doctor suggested Tolo may have endometriosis, a chronic disease believed to affect an estimated 10 percent of women of reproductive age, according to WHO data.
Caused by an overgrowth of endometrium-like tissue (uterine lining), endometriosis is primarily characterized by extremely heavy and painful periods, as well as pelvic floor dysfunction, bowel issues, and dyspareunia (pain during sex). The doctor recommended Tolo have a laparoscopy, an invasive surgical procedure required to get an official diagnosis and remove endometriosis tissue. But she refused: “I wasn’t going to undergo an invasive surgical procedure, or cut myself open,” she says. “That just wasn’t an option for me.”
Then in early 2026, Tolo started developing a concierge health service with her boyfriend Bryan Johnson, the technologist-cum-multimillionaire-cum-biohacker known for his quest to become immortal via rigid self-optimization and wellness protocols. During a clinical intake, she shared her lifelong struggle with suspected endometriosis—and he became obsessed with finding a cure.
Since hard-launching their relationship last December, Johnson has positioned his girlfriend as “the female Bryan Johnson,” with Tolo adopting a rigorous self-tracking protocol to optimize her health. Using $2.6 million in funding from Immortals, the wellness company the two founded, Tolo is tracking more than 1,500 biomarkers from sources such as her blood, urine, and stool over the course of her menstrual cycle, via “an elaborately choreographed four-hour techno ballet of scratching, sniffing, spitting, scanning, stretching, gripping, vibrating, flexing, plucking, poking, pulling, peeing, and pooping,” as one recent Business Insider profile put it.
It’s a relatively new role for the 30-year-old Tolo, who worked in fashion marketing before becoming Johnson’s executive assistant and special projects director for Kernel, his neurotech company, in 2021.
Describing herself as an introvert, she says she was initially uneasy about becoming “the world’s most measured woman,” as Johnson put it in a video from last August. (He’s also declared her vagina’s microbiome to be in the “top 1 percent” of all vaginal ecosystems.) Prone to depression and anxiety, she had a panic attack on week two of the protocol, prompted by her internet going down while she was trying to conduct red-light therapy. “It’s a deeply uncomfortable experience for someone who doesn’t love a routine,” she concedes. “And so all of that pressure just really got to me.”
But to hear her tell it, it all serves a larger purpose.
“Even when every part of me, individually, is screaming ‘Make it stop,’ I can see myself pushing myself to the absolute limit of what is possible, mentally and also physically, in my body. Because I’m doing this for women,” she tells me.
One of Tolo’s primary interests is coming up with reliable diagnostic and treatment methods for endometriosis, a process that the couple has been documenting on their social channels. Though Tolo never underwent surgery and has never been officially diagnosed with endometriosis, so far the two claim they have diagnosed Tolo with the condition over the course of 42 days using noninvasive methods, such as a saliva and blood test and an endo-specific ultrasound. (A transvaginal ultrasound and an initial MRI originally came back clear.) Their next step is creating an organoid using cells from Tolo’s menstrual blood—“essentially, me in a petri dish,” as she explains it—to test various interventions, the results of which she will compare next to a more conventional biopsy.